Bad Astronomy Blog

The Mysterious Case of a Nonexistent Alien Planet Discovered 160 Years Ago

4 hours 58 min ago

The first planet ever to be discovered was found in 1781. It was an accident of sorts; William Herschel wasn’t looking for a planet specifically. He was instead scanning the sky for double stars, cataloging them as he found them. But a star he saw one night didn’t stay still. Over the course of a few nights Herschel saw it move, and realized he had done something no human had ever done before: He had discovered a new planet in the solar system.

Less than a century later another planet was found. Unlike Herchel’s accidental discovery of Uranus, this one was found by applying math to the orbits of the known planets, looking for an unseen gravitational influence on their orbital motion. In a triumph of science, Neptune was seen just days after the calculations were done, quite close to the position predicted.

Not much later, just a decade or so, a lone astronomer made a startling announcement: He had evidence, he claimed, of yet another planet. This one, however, wasn’t orbiting our Sun at all! It was instead bound to another star, the smaller of two stars which in turn orbited each other in a binary system.

The binary is called 70 Ophichi (or 70 Oph for short), and the twist to this story is that although the evidence at first looked good, the planet itself didn’t exist. It was a phantom, a ghost manifested by small but persistent errors in the measurements of the stars’ positions.

As much as I love the history of planetary discoveries —especially ones that turned out to be erroneous— I was unaware of this particular story until I heard astronomy David Kipping tell it as part of his Cool Worlds video series. It won’t take long, and he tells it well, so please enjoy the yarn he spins:

How delightful! I also read the original paper in the Monthly Notices Kipping mentioned, and it’s fascinating. I was especially glad Kipping plotted the data, creating the illustration at the top of this article. In it, the more massive of the two stars (called the primary, and designated 70 Oph A) is placed at the graph origin, and the measured positions of the secondary star are plotted. You can see the overall elliptical shape of the orbit, but also the small offsets in the secondary star’s position. I will admit, as the astronomer Captain W. S. Jacob claims in the paper, it does look like a periodic swing to the offsets, as if some invisible object is tugging 70 Oph B first one way than another.

We now know, with further, more accurate observations, that no such planet exists there, and the offsets are the product of uncertainty in the telescopic observations that were, to be fair, done by eye.

But still, despite that, I must tip my hat to Jacob. He did his homework, made the best observations and calculations he could, expressed skepticism in his writing, and came up with what he thought was the best explanation. Mind you, again to be fair, this took a great deal of cleverness to dream up. Perhaps he had been influenced by the recent discovery of Neptune.

If anything, he was guilty of overconfidence in his own measurements. Still, technology eventually caught up with his imagination and we did start to find alien worlds. The field of exoplanet research is now a thriving one, which has moved beyond the simple discovery stage to one where we are beginning to physically categorize and model them.

Not so incidentally, we have since found planets orbiting other stars using the method Jacob pioneered in 1855. He may have been the first person ever to publish this idea, and for that he deserves acknowledgment. And in another twist, I can’t help but smile to think that 70 Oph was first cataloged and proven to be a binary star by none other than William Herschel himself.

So I’m glad I watched Kipping’s video, and learned about Jacob. While his work may now be a footnote in astronomical history, I still find it a wonderful story, full of scientific morality lessons. Express skepticism, don’t trust your data overly much, be keenly aware of any uncertainties, and try to get independent confirmation before making grandiose claims.

But also don’t let those boundaries constrict your imagination! Certainly known science must guide and shape it, and reality is the ultimate arbiter. But if we don’t sometimes stick our noses outside what we know, how will we ever push back those boundaries, expand our experience, and bring the unknown into the realm of the known.

Categories: Astronomy Headlines

John Glenn, the First American to Orbit the Earth, Has Died at 95

Thu, 12/08/2016 - 13:53

John Glenn has died. The cause of death has not been announced, but he was hospitalized at the Ohio State University Wexner Medical Center a week ago, reportedly in declining health. He was 95.

To call him an American hero is understating the case. He was a military aviator, signing up after the bombing of Pearl Harbor in 1941. He was a test pilot after that, and was also a U.S. senator from Ohio for 25 years, from 1974 to 1999.

But of course he is best known as an astronaut. He was in the first group of astronauts chosen by NASA, called the Original Group or, more popularly, the Mercury 7. He was also the first American to orbit the Earth, circling our planet three times on Feb. 20, 1962, in a Mercury capsule named Friendship 7. This was at the height of the Cold War and space race with the Soviet Union, and was a major step in the U.S. goal of putting humans on the Moon.

Friendship 7 is on display at the Smithsonian’s Air and Space Museum in Washington, D.C., and I highly recommend visiting it. It’s tiny—the size of a very small car. Yet Glenn stepped into it when it was mounted on the top of an Atlas rocket and rode that nickel/aluminum/fiberglass can into space. The bravery of an act like that is staggering, especially given how early on it was in our attempts to explore space.

But after splashdown his career as an astronaut wasn’t over: He flew again into orbit in 1998 on the Space Shuttle Discovery, making him, at the age of 77, the oldest human to fly. He lobbied hard to go and was chosen as a payload specialist by NASA. That decision was controversial; many people inside and outside NASA said that he was not “mission essential” and that his flight was political payback. Glenn himself disagreed, saying he trained hard for the flight and was qualified as a specialist. He also pointed out that there were geriatric studies that could be done on him to see what the effects of microgravity were and quite a few medical experiments were performed on him during the flight.

It’s interesting to note that Glenn holds another record as well: the longest gap in time between two spaceflights for any human. Given that it was 36 years, that record may stand for some time.

We’re at a time now when our first astronauts are mostly gone; Glenn was the last living member of the Mercury 7, and only seven of the Apollo Moonwalkers are still alive today as well. Even when recognizing and mourning his passing, I can’t help but think that we are at a cusp in our exploration of space, standing at the threshold of a huge leap forward in our ability to put humans into space. More countries than ever are building their own space programs with an eye toward crewed flights, and even private companies are working hard and making giant leaps in that direction. We’ve had people living continuously on board the International Space Station for more than 16 years now.

We have John Glenn to thank for much of this. He was one of the pioneers, one of the first humans in all of history to leave behind the Earth, even if only for a few hours. With all of his monumental accomplishments in his lifetime, my hope is that the one he will be remember forever for is this: He helped set in motion the greatest journey humanity has ever taken, a journey that, hopefully, will never end.

Categories: Astronomy Headlines

An Island of Stars in a Sea of Stars

Thu, 12/08/2016 - 06:00

I find some astronomical objects curious not so much in and of themselves, but also because of where they’re located.

Take M11, also called the Wild Duck Cluster. It’s about 6,000 light years away, and it’s an open (or galactic) cluster consists of about 3,000 stars. The cluster is something over 200 million years old, making it middle-aged; after a billion years or so such clusters dissipate as their stars interact gravitationally, ejecting members ones after another.

It’s still pretty compact, and its overall triangular shape is what gives it its name, looking if you squint) like a flock of ducks flying.

But what I like about it isn’t what it is, but where it is. It’s located in the constellation Scutum, a small region of the sky near the galactic plane. Our galaxy is a flat disk, and we’re inside it, so we see it as a broad band across the sky. By eye it looks like a fuzzy glow, but through a telescope it resolves into millions of stars. Billions.

And that’s why M11 is so cool: It sits in the foreground of those myriad stars, a knot of bright jewels set against a vast backdrop of millions of them.

The photo above is by my pal Babak Tafreshi, whose work commonly graces this blog (he has an annotated version as well on his own site). He took this shot from Iran. I love how you can see individual stars in the background, and the fainter ones just all merge together into that deceptively murky glow. Look how beautiful the dark wisps of interstellar dust are, too, some dense enough to totally block the light from stars behind them. Dust is an interesting physical component of our galaxy, but if you study stars it’s a pain, like trying to bird watch in a thick fog.

But it sure makes for a lovely shot. M11 is a great object; it’s easily seen in binoculars, and through a telescope it hints at its densely packed stellar citizenry. It’s up best in northern hemisphere summer, unfortunately, but if you get yourself (or someone you know) a telescope for the holidays, keep this one in mind for when it warms up outside.

Categories: Astronomy Headlines

The Universe Voids Itself, and Einstein Predicted It

Wed, 12/07/2016 - 06:00

Most of the Universe is empty space.

Duh. I mean, sure, that’s why we call it space. But what’s so very interesting about this is what you see when you look on very large scales; scales so huge that galaxies become mere dots. You might expect matter to be strewn evenly throughout the Universe, but it isn’t. Over these vast vistas, matter in the Universe is clumped, falling along huge filaments and sheets. These in turn are curved, closing in on themselves.

The Universe is foamy! It looks like a sponge, with matter clumping along the outside of the bubbles. Shortly after the Universe formed, dark matter clumped up, creating those filaments. These acted like gravitational scaffolding, its gravity attracting normal matter which then fell onto the filaments like Spanish moss hanging from tree branches. This material formed galaxies and clusters of galaxies.

Matter is still falling into those filaments today. As it does, the voids —the bubbles of the sponge— get bigger. We can predict how they grow using Einstein’s Theory of Relativity, which describes how the Universe expands and how the matter and energy in it behave as it does. This video from the Max Planck Institute for Astrophysics shows that growth in a computer simulation:

But there’s more to this: Dark energy, the weird stuff pervading space that’s causing the Universe to expand faster every day, is also in there, inflating the voids. Relativity, as originally formulated, doesn’t include that. If we can measure just how voids grow we can use that as a test of relativity and also understand better how these gigantic pockets of nothing get bigger. To do this, traditionally, astronomer measure that growth by examining the galaxies along the bubble edges.

But that turns out to be hard, because galaxies aren’t just falling onto the filaments. They also have what’s called peculiar motion, sideways velocity which makes measuring their precise velocity difficult. What to do?

A group of astronomers did something clever: Instead of looking at the galaxies, they looked into the voids themselves. Using observational data that shows distances to galaxies in the Universe— and therefore the locations of voids— they compare how these voids change in shape over time to what’s expected by computer models using relativistic calculations.

Not surprisingly, they find relativity to be pretty robust. The behavior of the Universe appears to obey the rules laid down by relativity, which is reassuring. I’ll note relativity has been tested approximately a bazillion times, and always comes up looking good.

So while that’s not exactly shocking, what I find interesting about this is that by looking at the voids instead of the galaxies around them. the astronomers who did this works were able to improve on previous methods dramatically, with uncertainties (that is, statistical accuracies) four times smaller than previous models!

That’s pretty dang good. We’re still learning just how the Universe behaves on the very largest scaled; heck, dark energy was only discovered in 1998! Research like this will help us understand what the Universe itself is doing as it ages and grows, and that to me is simply stunning. Even if you don’t understand the details of the work or the math behind it, know this: Astronomers are trying to understand literally everything, across all space and time.

And they’re doing a pretty good job of it.

Categories: Astronomy Headlines

An Irregular Mystery

Tue, 12/06/2016 - 06:00

Galaxies are massive collections of stars, gas, and dust (and dark matter, too). They come in four basic shapes: spiral (like our Milky Way), elliptical, peculiar, and irregular.

Irregulars are pretty much like the name says: They tend not to have an overall structured shape, but are, well, irregular. Still, despite that, some do have a semblance of shape, and it’s not always clear why.

Take IC 3583, for example. That’s the galaxy above, in a gorgeous Hubble Space Telescope image. It’s definitely irregular, but not quite. It appears to have a bar running across it, a thick rectangular structure. Many galaxies have bars (the Milky Way does across its core), even some irregulars. Usually they form from the weird way gravity works in galaxies; instead a single massive object in the center like the Sun anchoring the solar system, the mass of the galaxy is spread out, and that can cause odd structures to form like spiral arms and bars.

It’s possible a bar like that could get its start if the galaxy interacted with another one; the gravity from a bigger galaxy can pull on the smaller one and distort it, causing matter to move around and form bars like that.

As it happens, IC 3583 sits very near a much larger galaxy, the spiral M 90 — which itself looks weird; it has long streamers coming out of it as if it recently encountered another galaxy.

Aha! So is that it? These two had a cosmic tryst, both leaving the encounter a little shaken?

Not so fast. They appear to be close in the sky, but are they close together in space? Two objects can appear to be next to each other but at vastly different distances; like looking out your window past a tree in your yard to the mountains kilometers away. So it’s a legitimate question to ask if IC 3583 and M 90 are actually physically close to each other.

And the answer is… we don’t know. One way to get the distance to a nearby galaxy is to look at some of its brightest stars. We know how much light those stars give off, so by measuring their apparent brightness we can get a distance to the galaxy.

And that’s where this gets weirder. M 90 is a member of the Virgo Cluster, a nearby and decently large group of galaxies. We’re pretty sure M 90 is a member, and that puts it about 60 million light years away.

But looking at the stars in IC 3583 indicates it’s only a little over 30 million light years away, well in the foreground of Virgo. If that’s the case, the two galaxies are unrelated, despite appearances.

But wait! I said M 90 looks weird too; how can that be then? It turns out that galaxies like M 90 can be moving through the cluster rapidly, and the gas that exists between the galaxies can strip off the gas inside of rapidly-moving galaxies. It’s like being in a car when your dog decides to, um, make a foul odor, so you open the windows, letting the air blow through the car, stripping away the mixture of methane, hydrogen sulfide, and mercaptans.

So M 90 may be odd looking because it’s ramming through the cluster, and IC 3583 may look odd because sometimes irregulars are just odd looking. Coincidence.

I know that’s not an entirely satisfactory answer, but here we are. Galaxies, even nearby ones, are still quintillions of kilometers away, and that’s a long haul. It can be difficult to know everything about them… but then, that’s why we study them! We know way more about them than we did a century ago, but that doesn’t mean our knowledge is complete.

Science is a journey. There may not be a single, vivid end to that journey, though it tends to steer toward the path of reality. The fun part if the learning, of solving mysteries along the way. We may never finish —I certainly hope not!— but there’s a lot to see and do along the way.

Categories: Astronomy Headlines

Followup: Why The House Science Committee’s Climate Change Denial Is So Wrong

Mon, 12/05/2016 - 05:45

Last week, I wrote about an appalling tweet by the U.S. House of Representatives Committee on Science, Space, and Technology. The Committee —currently run by a GOP majority— has a history of outrageous climate change denial, and also has a history of tweeting about it.

But even for them, the tweet from Thursday, Dec. 1 was outrageous: It linked to a ridiculously bad article by climate change denier James Delingpole, who is known for ramping up the hyperbole to 11 when he writes on global warming. He in turn got his bad data from another noted denier, David Rose, writing for The Daily Mail, the Mos Eisley Tavern of anti-reality aficionados.

The claim made by Rose is simple: Temperatures since Feb. 2016 have plummeted by a full degree Celsius in more recent months, casting doubt on the reality of global warming.

As I pointed out in my own article (and with far greater detail given by Tamino at the blog Open Mind), Rose’s claim is completely wrong. He cherry picked data so severely that they’re essentially meaningless; the equivalent of flipping a coin once, having it come up heads, and then declaring it always comes up heads.

He looked at patchy data with high uncertainty from a very short time period and tries to make conclusions about it. What he (and in turn Delingpole and then the House Committee on Science) ignored was the trend. These shenanigans have been graphically debunked by climatologist Gavin Schmidt, who is the director of the NASA Goddard Institute for Space Studies, and is a noted expert in climate change.

Here’s the animation:

To create this animation, Schmidt used land surface temperatures from GISTEMP, which is measured using a variety of methods including meteorological stations. He shows that yes, there is a large drop from earlier this year to October, due in part to El Nińo subsiding. If all you see is the first frame of this animation, you might suppose something really is weird!

But there’s more. The second frame shows the same measurements going back much further in time, to 1970. The y-axis is what’s called the “temperature anomaly”, the deviation from some average (in this case, the temperatures from 1951 – 1980; if the anomaly is 0 then you’re right on average, if it’s a degree above average it’s shown as +1, and so on). As you can see, once you look back more than a few months or even years, there is a clear upward trend to the temperatures.

The third frame overplots the average temperature for each year in red, making the trend more clear (the dashed line is an estimate for the rest of 2016 using previous years as a guide). The fourth frame corrects those averages for El Niño (the technical name is El Niño-Southern Oscillation, or ENSO); it’s actually not a huge correction, and again the trend is clear.

The fifth frame shows a mathematical fit to the data to just show the trend, and as you can see it’s heading up.

The other thing to notice here is that we see lots of very short-term fluctuations, some swinging well over a degree over small periods. But that’s not surprising! The shorter the time, the more you expect the temperature to move; the average daily temperatures over a week can be all over the place, but the annual average temperatures should be relatively stable from year to year.

Yet, despite that, the trend is obvious: The world is heating up.

This is precisely why we say Rose was cherry picking. Whatever his motivations, he only showed a very limited slice of what’s really going on, and in that way hid reality from everyone who didn’t know to look deeper.

Or who didn’t want to look deeper. As I’ve written before, the science is the science, but the inconvenient truth about global warming is that it goes against a lot of political ideology, especially when that ideology is fueled by money from the oil industry.

And without a doubt that’s why the House Science Committee took to Twitter; they wanted to advance their dogma, truth be damned. They are not interested in actual science, or in reality. They are only interested in their agenda, and that agenda is to further the cause of fossil fuel, even if it means setting the world on fire.

Categories: Astronomy Headlines

The House (Anti-)Science Committee Strikes Again

Fri, 12/02/2016 - 05:45

The House Committee on Science, Space, and Technology is, ironically but shocking to no one who understands the majority party, quite anti-science. For years now, the committee and its chairman, Lamar Smith (R-Texas), have been merciless in their attacks on both climate scientists and the National Oceanic and Atmospheric Administration (NOAA). Smith—who receives a large amount of funding from fossil fuel interests—has been subpoenaing NOAA staff and data repeatedly in what is a transparent attempt both to create a chilling effect and to directly prevent them from doing their very important research into human-generated global warming.

The Committee's Twitter account often reflects this ideology. And this afternoon, to the dismay of many, they tweeted a climate-denying “news” story from Breitbart.

Yes, that Breitbart, the racist, misogynistic über-right-wing site that calls itself a voice for the “alt right” movement, which is—as my Slate colleague Jeremy Stahl says—composed of “Neo-Nazis in suits and ties.”

The content of this tweet is the same sort of thing you’d get if you fed a bull 20 kilos of Ex-Lax and stood behind it for a while. Global warming, of course, is real. The Breitbart article in question is written by James Delingpole, a flat-out climate change denier who has a history of writing grossly misleading articles about global warming. He gets this information from yet another climate change denier, David Rose, who wrote an article for the execrable Daily Mail claiming that global temperatures have dropped by an entire degree Celsius since this summer. Contrary to what the Daily Mail might have to say, global temperature is not increasing.

In a nutshell, Rose is guilty of extreme cherry picking. He looked at a single temperature datatset from a specific layer of the Earth’s atmosphere and only used measurements over land. And to make matters worse, he only used data going back to 1998, a big no-no: That year was unusually warm, so starting there falsely makes it look like temperatures haven’t risen much.

He also is chasing local fluctuations and ignoring the decades-long trend. And that trend is up. The Earth is heating up. If you want more details, Tamino at Open Mind debunks Rose’s claims quite thoroughly.

As wrongheaded as it is, this kind of climate denialism is de rigeur for people whose stance is so anti-science. I’m used to it, awful as it is. But it’s the fact that the House Committee linked to Breitbart that’s so disturbing.

And this isn’t even the first time this Twitter account has linked to a Breitbart article. It did so on Sept. 8:

And then, after finding all this out, I found (via Karen James) that Committee Chairman Smith actually has written for Breitbart! As physicist Robert McNees points out, this has been going on for some time now.

And mind you, all this was before Trump was voted into office. These tweets, and the information they cite, are a scary reminder that climate deniers will feel emboldened by Trump’s election. Trump’s team is already planning to cut global warming research at NASA. As winter approaches, we’ll likely see more reality-challenged senators bring in snowballs to the floors of Congress and say, “What global warming?” every time a cold snap arrives, even though a lot of the brutal “polar vortex” conditions are actually tied to the effects global warming.

The good news is some in Congress do recognize the reality and the importance of climate change. Rep. Don Beyer (D-Maryland), for example, who tweeted:

Good on him! We need more people like him in Congress willing to speak up against this sort of denialism.

The stakes here are as high as they can get. Climate denialism by Breitbart now gets the imprimatur of the federal government. This cannot stand. Act accordingly.

P.S. If you want to contact the Committee directly about this, their phone number is 202-225-6371. If you do, be brief, and be polite! If you have a Representative on the committee, mention that as well.

Categories: Astronomy Headlines

Russian Resupply Rocket Lost During Launch

Thu, 12/01/2016 - 10:58

News is still coming in right now, but it looks like a Progress capsule loaded with supplies for the astronauts on the International Space Station was lost as it was heading up into space this morning. It was uncrewed, so there was no loss of human life.

Jason Davis at The Planetary Society has details, and you can also get more at SpaceFlightNow. The launch started off well, but the third stage cut off prematurely. Contact was lost a little over six minutes after liftoff, and Roscosmos, the Russian space agency, has confirmed the loss of the vehicle 190 kilometers over the Tuva mountains in south central Russia; the Progress capsule lost altitude and burned up in the atmosphere. There are unconfirmed reports of debris in the remote area as well though no injuries reported.

Here's video of the first few minutes of the launch:

The good news is that the ISS is well stocked, and a Japanese supply ship is due to launch in a week or so, so the astronauts are in no danger.

I’m keeping my ears open for more news; it’s unclear how this will affect future Russian launches, including astronauts to ISS. I’ll note SpaceX just announced their return to flight mission for a Falcon 9 on Dec. 16; this will be their first launch since the pre-launch explosion of a Falcon 9 during fueling on Sep. 1, 2016. That’s good news, as they have several resupply missions planned to ISS as well.

More info will be added here as I hear and confirm it.

Categories: Astronomy Headlines

How the Moon Got Its Weird

Thu, 12/01/2016 - 06:00

Our Moon is really weird.

I mean that literally. It has a lot of physical qualities that are pretty hard to explain. For example: It’s big, fully a quarter the diameter of the Earth. Excluding Pluto and Charon, it’s the highest known ratio of moon to parent body size for any large object in the solar system.

There’s more. All other moons in the solar system orbit over their parent planet’s equator. Our Moon’s orbit is tipped by much more; it actually is tipped 5° to the Earth's orbital plane around the Sun; the Earth itself is tipped by 23° to that. Also weirdly, while there are some differences, overall its composition is similar to Earth’s. That’s unusual too; most moons are way different than their planets.

A lot of these problems with our Moon were solved when the Giant Impact hypothesis was proposed. Early on in the solar system, a disk of material orbited the Sun, and it was from this disk the planets formed. Small bodies condensed out of it, collided, and grew to become the planets. At some point, tens of millions of years after it initially formed, the Earth was whacked by a Mars-sized object at a glancing angle. This flung a huge amount of material into space, which formed a disk over Earth’s equator. The Moon coalesced from this ejecta, and the Earth was left spinning rapidly, with a day just five hours long. Over time, interactions between the Earth and Moon slowed our spin and moved the Moon out, away from the Earth to where we see it now.

That explains a lot of the weirdness we see from the Moon; its unusual size is due to the large amount of material blasted into space, for example. But there are problems. If the Moon formed over the equator, why is its orbit tipped by so much now? Also, in the impact models, the Moon should have a lot of material from the impactor, but instead is closer to an Earth-like composition. Why?

A group of scientists think they may have found the answer. And as a bonus, it explains yet another odd thing: Why the Earth is tilted by 23° to its orbit.

What they propose is a modification to the giant impact idea. In their model, they have a much more energetic impact. The tremendous power of the collision set the Earth spinning with a two-hour day, faster than in the classic impact hypothesis. The higher energy also meant the material ejected mixed a lot more, so that both the Earth and Moon wound up with similar compositions.

Then comes the really strange part. You know how a kid on a swing can make their arc go higher by pumping their legs? By doing that they transfer the energy of their legs’ motion into the swing. But they have to time it right to make it work, doing it at just the right time in the arc. When two cycles line up like this it’s a called a resonance, and it’s a huge influence on the motions of moons and other bodies.

After the Moon formed, it started moving away from the Earth due to the complicated dance of gravity and tides. I explain how this works in Crash Course Astronomy: Tides, if you want the details. The outcome of this is that the Moon’s orbit slowly expanded and the Earth’s spin slowed.

In the new model though, there’s a twist: The giant impact torqued the Earth hard, so much so that our planet’s pole was aimed more toward the Sun than it is now. This changes that tidal evolution of the Moon. As it moved away it went through a series of resonances, some connecting the way it moved away from Earth with the Earth’s motion around the Sun (like the way a kid’s legs connect with the swing’s motion).

What the scientists found in their models is that this affected both the tilt of the Moon’s orbit as well as the tilt of the Earth itself. As the Moon’s orbit expanded, it also moved around, changing its orientation. The Moon’s tides tugged on the Earth all that time, eventually yanking the Earth closer to being upright (the Earth’s orbit was unaffected, though).

In the end, the Moon settled into its current orbit, tipped 5° to the Earth's orbital plane, and the planet stayed at its 23° tilt to its orbit around the Sun. This video shows the effects graphically:

The Sun is off to the left, and the Earth’s axis points near it. As time goes on (starting less than a million years after the impact) the Moon’s orbit changes in orientation, tilt, and shape, and the Earth’s axis changes, too.

I’ve left out a lot of details because they’re complicated and would take a lot to explain (feel free to read the paper, but there’s a lot to it). Still, this is the meat of it. The big question is: Is this what actually happened 4.5 billion years or so ago?

That’s a different question. Just because this new idea explains more stuff we see now doesn’t make it right. Lots of other ideas have come along, and no doubt more will. Perhaps this idea is correct, and still needs modification (for example, we know a lot of things happened after the Moon formed; its far side and near side are really different, and more hypotheses have been proposed to explain that). Maybe something better will come along that explains even more.

But that’s science! For a long time —centuries, millennia— we had no more than guesses on how the Moon formed. As we studied it more we learned more about it, and were able to cull a few hypotheses. Then we went there and got samples, pieces of the Moon we could study in the lab. More mysteries surfaced, and the giant impact idea explained a lot of them. But it’s been modified, over and again, tweaked here and there, and now we may very well be closing in on the complete history of how our gigantic satellite came to be.

There are a lot of reasons I love science, but one of them is that it doesn’t flinch from telling the big stories, and welcomes changes to make the story better.

Correction, Dec. 1, 2016: I originally wrote that the Moon is tipped 5° to the Earth's equator, not the Earth's orbital plane. 

Categories: Astronomy Headlines

Another Jumping Sun Dog

Wed, 11/30/2016 - 06:00

Just recently I wrote about one of the coolest and weirdest weather/optical phenomena I’ve ever seen: crown flashes, also called jumping sun dogs. They’re streamers of light above storm clouds that appear to dance and flash, sometimes quite rapidly, looking like search lights or huge light sabers.

They’re almost certainly caused by long ice crystals above the cloud that align themselves with the cloud’s electric field. If you see them from the right angle, they bend (or refract) the sunlight toward you, causing the glow. When lightning erupts from the cloud to the ground (or inside the cloud) the electric field changes radically, realigning the ice crystals. When this happens they suddenly bend sunlight in a different direction, causing the glow to shift.

By coincidence, a BA reader named Mikhail Chubarets sent me an email a few months back (before I wrote the article linked above), letting me know about an amazing video of a crown flash, but I missed his email! I was going through some old ones and spotted it, so now I get to share this short but way cool video with you:

The video was taken in Zvenigorod, a city in Moscow Oblast in Russia, on July 3, 2016. It really shows a lot of detail, and I gasped out loud at the 1:25 mark when it shows the glow sweeping rapidly like the blade of a sword into a new position.

I have some mixed feelings about this, to be honest: While this is one of the most astonishing optical phenomena I’ve ever seen, the things is, I’ve never seen one for myself. I recently was able to scratch Kelvin-Helmholtz clouds off my “to see” list, as well as (yikes) a tornado. But this? Crown flashes are pretty rare; besides having the ice crystals aligning correctly you also have to be in the right spot for the geometry to line up, otherwise the sunlight isn’t bent your way. They’re rare enough that I hadn’t even heard of them until a couple of years ago.

It seems unlikely I’ll ever witness one. Ah well. I can add that to a long list of things still to witness (like a total solar eclipse, a full-blown aurora, a display of undulatus asperatus, and more). I do get around, and I do tend to look up, so I can still hope. There are a lot of truly wonderful things to experience on this planet of ours.

Categories: Astronomy Headlines

A (Frozen) Great Lake of Water Is Found Beneath the Surface of Mars

Tue, 11/29/2016 - 06:00

Mars has long been a target of human curiosity. A blood-red eye in the sky, hanging, baleful. Our understanding of it has changed over time; it was thought to be somewhat Earth-like for a while, but then we sent space probes there and found it to be a desiccated, dead world.

Well, at least for now. We have pretty conclusive evidence it once had plentiful liquid water on the surface, including lakes, rivers, and even oceans. That was eons ago; the solar wind stripped away the atmosphere from Mars, and the water mostly boiled away with the air.

Mostly. We’ve known for a long time there’s lots of water ice on the planet; both poles have water ice caps on them several kilometers thick (in turn capped by seasonal layers of frozen carbon dioxide —dry ice— a few meters thick). You kinda expect that at the poles. But there’s also evidence for water just under the surface at mid-latitudes: Small impacts from asteroids have excavated ice that can be directly seen. These are wee craters, so it’s not clear just how much ice there is down there.

But now scientists using a radar mapper on board the Mars Reconnaissance Orbiter (or MRO) have found more water ice at these lower latitudes, and a lot of it: The volume is enough to fill Lake Superior, the largest of the Great Lakes in North America.

Yeah, that’s a lot of ice.

It’s located in a region called Utopia Planitia (Trek fans will recognize this as the location of the Starfleet Yards where the Enterprise-D was built), at a latitude of 45° north, so quite literally at mid-latitudes. While it’s only a tiny fraction of the total water ice known to exist on (or under) Mars, it doubles the amount known at these latitudes.

It was found using a radar mapper on MRO. Called SHARAD, it sends pings of radar down to the surface, which are reflected back up to the satellite and recorded. Different substances reflect radar differently; the rocks on the surface aren’t particularly good at it, which is why the radar can penetrate the ground. Water, on the other hand, reflects radar quite well, so SHARAD can detect water ice down to a depth of a kilometer below the Martian surface.

Scientists focused their attention on a region in Utopia Planitia that features lots of odd, scalloped terrain (aresain?), which is similar to places on Earth in the Arctic that have underground ice. Combining the data from over 600 MRO passes indicates how much ice there is. The area of the ice deposit is over 300,000 square kilometers and the thickness ranges from 80 to 170 meters. So yeah, that’s a goodly supply of ice.

This is pretty good news for future exploration and colonization plans. Ice is critical for Martian living; it can be melted to drink, broken into oxygen and hydrogen for air and rocket fuel, and can protect inhabitants from solar storms (on Earth our air does this, but Martian air is less than one percent as thick as ours; ice does an excellent job of absorbing radiation).

One last thing: How did the ice get there? One idea is that Mars’ axial tilt varies wildly over time. When it flips, the poles become much closer to the previous equator. The ice sublimates, turning into a gas, which then recondenses in other locations. It can mix with dust and snow out in the mid-latitudes, eventually getting buried.

That’s amazing. An entire planet flipping over like that! It’s hard to imagine what chaos that would wreak on the climate, even for a planet with so little air. Happily, our Moon provides stabilization against this kind of event; it torques the Earth’s axis and prevents it from making big excursions.

Mars is weird. But that’s good! Studying it helps us put the Earth in context with the other planets, and in turn helps us understand our own planet. And that’s good, because we live here.

Categories: Astronomy Headlines

FOLLOWUP: More on Trump’s Catastrophic Plan to Gut NASA’s Earth Science

Mon, 11/28/2016 - 05:45

As expected, the days leading up to Donald Trump’s inauguration are like the timer on an atomic bomb ticking down to Armageddon. Every day there’s some new horrific thing he and his cronies do, and the only predictable thing they do is find the worst possible choice to make in any given circumstance.

This was brought home, hard, when Bob Walker, a top Trump advisor, recently said that the new administration will gut NASA’s Earth science program. The reason: Trump’s long-standing and implacable climate science denial. And this, of course, is the inevitable outcome of decades of Republican attacks on science.

When I wrote about this the other day I went into some detail, outlining the blatant hypocrisy of Walker’s statements; essentially everything he said about climate change was provably false, and the charges he aims at climate scientists can actually be lain at the feet of the GOP.

Not long after I posted my own piece, the CBC radio show “As It Happens” posted an interview with Walker where he reiterates his erroneous claims.  They then contacted me and asked me what I thought of Walker’s statements.

Yeah, you can just guess how I feel about them. I talked with “As It Happens” host Carol Off about it, and the interview is online. They have a transcript as well, but it doesn’t include everything I said; I recommend listening to the whole interview (which is roughly nine minutes) so that you get all the info. As a bonus, you’ll also hear just how angry and frustrated I am by this utter disaster.

In the interview I mention a few things I want to make sure everyone sees. One is that Walker tries to downplay the “climate consensus”, the fact that there is overwhelming agreement among climate scientists that global warming is real and caused by humans. The best overview of this is at Skeptical Science. John Cook— who writes for that site and is also the lead author on one of the many studies about the consensus— also wrote a great article about it for The Conversation.

97 percent of climatologists agree on this. 97 percent. Don’t buy into Walker’s nonsensical claims about this; he’s using thin rhetoric to sow doubt where it doesn’t exist.

I said that Exxon knew about fossil fuel induced global warming for 40 years; DeSmogBlog has more on that. It’s pretty damning.

Also in the interview I mentioned Marshall Shepherd, who was president of the American Meteorological Society. He coined the wonderful term “zombies of denial”, so please read more about that.

We need to arm ourselves against the barrage of weaponized denial we’ll be facing for the next four years. Trump himself, and his proxies as well, have no trouble at all just bare-faced lying to the American public. We must stand ready to fight against this. Whether it’s the racism, the xenophobia, the misogyny, or the attacks on science, it is no exaggeration to say that our culture, our country, and even our very existence depends on us.

Climate change is already one of if not the biggest threat our species has faced. I still have hope: When challenged, Americans have a history of meeting adversity head on. As I’ve written before:

When Americans are challenged, we rise up and do our best. I honestly and truly think that we can, that this is an opportunity to show the world that we won’t stick out heads in the sand. We’ll face this issue, and we’ll figure out how to minimize it, how to circumvent it, how to manage it. I don’t believe in phony platitudes, or empty motivational slogans, so my words here don’t ring hollow to me. They’re simply the truth. We went to the Moon, we put rovers on Mars, we look outward to the Universe and forward into the future. That’s America. Climate change is one of the largest existential threats we face today. It’s time to face it down.

I wrote that before the election, but it’s still true. It’ll just be a lot harder with Trump and the GOP in charge. That means we have to dig in and deal with them, too. We can do this. We have to.

Categories: Astronomy Headlines

Starry Starry Swing

Sat, 11/26/2016 - 06:00

Longtime BABlogee and music composer Greg La Traille sent me a note letting me know about an amazing art exhibit in Zürich, Switzerland called “Starfield”, but really it should be called “Star Swing”.

Why? Well, for one thing, it’s a swing. But not just an ordinary piece of playground equipment: It’s connected to a Microsoft Kinect that uses the height of the user’s eyes, measures the angle of the ropes holding the swing, then calculates the trigonometry necessary to make it look like you’re swinging over the galaxy itself!

Watch:

I love this. What fun! And because the projection is digital, it can be swapped out with any data where 3D info is available (or can be simulated). You could swing over the Moon, or a black hole, or Saturn’s rings… or scenes on Earth like, say, Angel Falls or the top of K2. Starfield uses data from the WorldWide Telescope, too.

The idea comes from a French art collective called Lab212 (they have a lot of other cool experimental art installations worth checking out, too), and was originally created by Cyril Diagne and Tobias Muthesius. It’s at the Museum of Digital Art in Zürich.

I make no bones about having a weak stomach; reading in a car makes me ill, and playing on a kid’s swing can be somewhat touch-and-go for me. So I wonder if riding on Starfield would be a good idea for me.

Still, I’d love to find out. What a wonderful and lovely idea. Math! Science! Art! They’re all related; a combination of how the Universe is and how we experience it. When they are intertwined it enriches them all.

Categories: Astronomy Headlines

Jupiter Unwrapped

Fri, 11/25/2016 - 06:00

On Mar. 8, 2016, Earth lapped Jupiter in their race around the Sun. Earth orbits closer to the Sun than Jupiter, and so moves much more rapidly. Like a car on the inside track passing one on the outside, this meant that Earth was as close to Jupiter as it would be all year.

Astronomers call this event opposition, because it means the outside planet is opposite the Sun in the sky as seen from the inside planet. So, to us on Earth, Jupiter rose when the Sun set, was up all night, and appeared as big through a telescope as it would until the next opposition (which will be on Apr. 1, 2017).

During the March opposition, planetary photographer extraordinaire Damian Peach aimed his 35 cm telescope skyward and shot video of the huge planet. Using software to pick and choose which frames minimized the blur of the atmosphere, he assembled the amazing image of Jupiter shown above. It “unwraps” Jupiter, mapping the spherical surface onto a rectangle. This distorts some of the features near the poles (like when a similar map of Earth makes Antarctica stretch all the way across the bottom, or magnifies how big Greenland is), but still gives a great overview of what’s what.

The most obvious feature is, of course, the Great Red Spot, a persistent storm that is at least four centuries old, and possibly far older. For reasons unknown, the Spot has been shrinking of late, but it’s still big enough to swallow the entire Earth without our planet touching the sides.

My favorite part of this image is the turbulence downstream of the Spot, as the circulating atmosphere flows around it. It’s much more apparent in the big version of this image, and I encourage you to take a look.

You can also see the banding of Jupiter, circulating weather systems that stretch all the way around the planet (you can find out all about this and more in my Crash Course Astronomy episode about Jupiter). Smaller pale circular storms dot the mid-latitude southern hemisphere, and it’s easy to spot similar features all over the planet.

Using all the best frames from the observations over Mar. 18 - 22, Peach created this stunning video of the monster planet rotating.

Jupiter spins once every 10 hours, so Peach had to match each image taken over five days carefully to get them to fit into the animation. It really gives an impression of the immensity of the planet; remember, 11 Earths would fit across Jupiter’s face!

Jupiter is always one of my favorite targets when I take my own telescope out. It’s big, easy to see (it’s the fourth brightest natural object in the sky, after the Sun, Moon, and Venus), and the motions of its four biggest moons easy to spot night after night, and sometimes in just a few hours.

Unfortunately it’s not well situated to observe now; it rises around 3:30 in the morning and sets in the afternoon. But starting in 2017 it’ll be gracing our early evening skies again, and I hope for a chance to take some time getting reacquainted with it. If you have an opportunity to see it —and many astronomy clubs have public star parties— I urge you to take it. Your view may not be as a good as Peach’s, but it hardly matters. Seeing a planet like Jupiter with your own eyes is an experience you won’t soon forget.

Take a look at Peach’s collection of Jupiter observations, as well as his website in general. Trust me: You’ll be glad you did.

Categories: Astronomy Headlines

Happy Thanksgoating

Thu, 11/24/2016 - 06:00

I’ll be the first to admit there’s a surfeit of things to be thankful about this particular fourth Thursday of November. If you’ve been paying attention at all the evidence is pretty strong. I need not go into details.

Unlike a serving of yams, I won’t sugar coat it. This isn’t a feel-good, hey-everything-will-be-fine post. I’m very, very worried about the future, well beyond the next four years.

But I’ll tell you what. I’m thankful for and to the people who speak up, who are vocal, who have everything to lose and still put it all on the line. America is based on people telling others to stuff it when they become oppressed, and while our society has been and remains imperfect in many ways, this is still one of its greatest strengths.

If you need something to hold on to, find what it is and grab it with as much fervor as you can muster. But save some for the road ahead, because you’ll need it.

For me, that anchor is manifold. It includes true patriots who fight for what America means. It includes my friends and family. It includes the Universe itself, which I honestly do turn to in times of stress to remember that there is majesty and beauty and vast scale against which to put my own life in perspective.

And my goats. They help too.

Whatever it is for you, hold on. We all need you, very much. And we will continue to need to, even after we get out of this current mess. America is never finished; there’s always more to do, and we need everyone we can to help it along.

Categories: Astronomy Headlines

Trump’s Plan to Eliminate NASA Climate Research Is Ill-Informed and Dangerous

Wed, 11/23/2016 - 09:03

In a month where it’s easy to get outrage fatigue at the incoming Donald Trump administration, he still finds a way to be brazenly awful and make terrible, dangerous decisions:

In an interview with the Guardian, Bob Walker, a senior Trump adviser, said that Trump will eliminate NASA’s Earth science research. This is the mission directorate of NASA that, among other important issues, studies climate change.

In other words, Trump and his team want to stop NASA from studying climate change. From the article:

Nasa’s Earth science division is set to be stripped of funding in favor of exploration of deep space, with the president-elect having set a goal during the campaign to explore the entire solar system by the end of the century.

This confirms essentially the same comments made by Walker in late October at a Federal Aviation Administration committee meeting.

The motivation behind this is clear: Utter and complete denial of science. I’ve written many times that Trump denies climate change is even real, saying it’s a Chinese hoax. He’s said there’s no drought in California, even while the majority of the state is under intense drought conditions. He picked a climate change denier to advise him on energy policy during his campaign, and picked an even more egregious denier to head up the EPA transition effort. In a recent statement he appears to have softened that hard-line stance, but given the torrent of lies dropping from Trump’s mouth, his history of science denial, and Walker’s current statements, I see no reason to believe Trump’s attitude has changed.

Actions speak louder than words, and his actions are clear.

If this slashing of NASA Earth science comes to pass, it will be a disaster for humanity. This is no exaggeration: NASA is the leading agency in studying the effects of global warming on the planet, in measuring the changes in our atmosphere, our oceans, the weather, and yes, the climate as temperatures increase. They have a fleet of spacecraft observing the Earth, and plans for more to better understand our environment. That’s all on the chopping block now.

Especially irritating are the details of what Walker said. Calling climate change research  “politicized science” is so ironic you could build a battle fleet out of it, because it was the GOP who politicized it. They are the ones who attacked it as a party plank, they are the ones who have been taking millions in fossil fuel money to fund an organized disinformation campaign about it, they are the ones who harass climate scientists.

The specific example that crystallizes all this? Republicans love to claim that progressives started using the phrase “climate change” instead of “global warming” because the Earth wasn’t warming. This is 100 percent pure bull crap. First, the Earth is warming; the “pause” isn’t real. Second—and this is the real kicker—it was Frank Luntz, a Republican strategist, who convinced Republicans to switch phrases because the term “climate change” is less frightening, and therefore easier to downplay.

This is the modern GOP. Scream and wail about what “the left” is doing, when in reality it’s the GOP who are to blame.  It’s all very calculated, and downright Orwellian. The hypocrisy is palpable.

Walker also said, “Earth-centric science is better placed at other agencies where it is their prime mission” is particularly galling. The best agency for that would be the National Oceanic and Atmospheric Administration, which for the past two years has been under relentless attack by the GOP in the form of Lamar Smith, R-Texas, chairman of the House Committee on Science, Space, and Technology. He has done everything he can to tie NOAA in knots and prevent them from studying global warming, including subpoenaing ridiculous amounts of information and intimidating its administrator, the astronaut and national hero Kathryn Sullivan.

Lamar Smith is the modern day Joseph McCarthy. But we’re still waiting for his at long last sense of decency.

So Walker saying Earth science is better done at NOAA is a lot of malarkey. Worse, NOAA relies heavily on NASA for mission support, including launching satellites. How will that be affected under a Trump presidency?

There’s one other exasperating thing Walker said, and it’s a pants-on-fire doozy:

Walker, however, claimed that doubt over the role of human activity in climate change “is a view shared by half the climatologists in the world. We need good science to tell us what the reality is and science could do that if politicians didn’t interfere with it.”

That is complete garbage. “Half the climatologists”? In reality, at least 97 percent of climatologists agree that humans cause global warming, and the data show you can’t explain the current rising temperatures without human influence.

The final wail from the ghost of Orwell is that last sentence by Walker. He’s a politician, and he’s interfering with science.

And need I remind you, this is all happening while the planet has seen a string of record breaking heat, month after month, where the Arctic sea ice is melting in unprecedented ways, where President Obama has said climate change and its denial is a threat to national security, and a top military advisory board has said the same thing.

I find it outrageous that Trump won this presidency in large part by stoking fear in people, yet he denies the single biggest thing we actually should be scared of.

Is there any good news in this? Perhaps. Just because Walker says this will happen doesn’t mean it will, though that is thin gruel to get sustenance from. Some people are fighting back; for example the NOAA has told Smith they won’t acquiesce to his awful demands, and climate scientists like Michael Mann, Gavin Schmidt, and Katharine Hayhoe are speaking out.

Hopefully the public will as well. Contact your representative and senators. Tell them that the Earth is a planet, and studying it, studying its climate and our effect on it, is absolutely part of NASA’s mission, and perhaps its most critical one.

Categories: Astronomy Headlines

Mars Is Going Through a Bit of a Dry Spell. How Do We Know? Rusty Meteorites.

Wed, 11/23/2016 - 06:00

I love meteorites. I have quite a few myself; while I’ve never found one on a hunt I’ve bought them from collectors. There’s a wealth of science in them; many are as old or even older than Earth, having formed in the early solar system. Others are from asteroids that got smacked by other asteroids, the impact sending out shrapnel that eventually impacted Earth.

Of course, other planets get hit by them too. We’ve seen asteroid (or comet) impacts on Jupiter… but we’ve also seen meteorites on Mars. In 2005 the rover Opportunity found a meteorite on Mars, the first time we’d ever seen one on another planet’s surface. Many more have been found since then.

It turns out that finding meteorites tells us more than just about them: They can be used to measure the environment in which they sit, too. A team of scientists used some Martian meteorites to do just that, and discovered something rather interesting: Mars has been very, very dry for the past several million years.

Now, we know Mars is dry. But there’s some evidence for moisture; for example, the Curiosity rover found daily and seasonal moisture exchange between the surface and the atmosphere.

Lots of meteorites contain iron. Some are mostly iron, like a peculiar looking one found by Curiosity just recently. Others are mostly rock (called stony meteorites), but even they are rich in iron. While out in space that iron is pristine, but once it lands on a planet like Mars, weathering can begin, including oxidation. Under water, for example, the iron in meteorites will rust. That can also happen if there’s moisture in the air, too.

Combining all this, the scientists looked at several meteorites found by rovers on Mars, including the chemical analysis done by the rovers (Opportunity has a spectrometer, an instrument that can determine the chemical composition of specimens). They examined the data and found that the meteorites contained oxidized iron — most likely due to Martian weathering.

They also were able to make various assumptions about the ages of the meteorites; for example some are near a crater that has been dated at 50 million years old. That’s an upper limit to their age; they could have been from that impactor, or they may have fallen later. Others were dated using similar methods.

What the scientists found is that the rate of oxidation is at best the same as what it would be at some of the driest places on Earth (like Antarctica), and could be far slower than that, perhaps as much as ten thousands times slower.

What this means is that in recent times, at least at these locations, Mars is dry, dry, dry. Perhaps at other spots the conditions are wetter, but the resting places for the meteorites are positively desiccated. As it happens, Mars may be in an interglacial period, an epoch of time when it’s a tad warmer than usual, with drier conditions at the equator. These meteorites support that idea.

In some sense that’s good news; it means that interpreting the geology at these places is easier, since weathering is low. But it also means that finding extant life on Mars may be harder. Looking at higher latitudes where we know there's ice under the surface is still worth trying, though.

I love all this. One aspect of doing scientific investigation is looking around you (or whatever you’re using to look around) and seeing what there is to see, inventorying it, and then figuring out what you can do with the tools at hand. And in so many cases, nature provides! It’s funny to think that rocks from space can hit a bigger rock from space, and from that we can make all sorts of measurements, even from tens of millions of kilometers away.

But this is why we explore space, why we send rovers and landers and orbiters and flybyers to other worlds. Sometimes we don’t know what we’ll measure until we get there, and we won’t even know how we will measure them until we get there. But once we’re there, entire worlds are open for us to investigate.

Categories: Astronomy Headlines

No, There’s No “Huge Blue Globe” in Front of the Sun (Sigh)

Tue, 11/22/2016 - 05:45

For reasons that elude me now, I decided to check on Facebook Sunday night before going to bed. On the right sidebar, I noticed that it said that “NASA” was trending. That surprised me; had I missed some important event or amazing new Hubble image being released?

I clicked on the link, saw the news item, and let out a long sigh. This is what I saw:

Yup. Another “Space telescope takes a picture we don’t understand and therefore it must be a UFO/Nibiru/NASA coverup/End times/cats-and-dogs-living together situation”. In this case it’s a huge blue globe appearing “in front of the Sun”. Except, of course, it’s nothing of the sort.

Pardon my snark, but this ain’t my first rodeo here. I’ve had to debunk stuff exactly like this dozens of times, and it’s almost always the same story.

On the Facebook trends page there were links to a few articles, the first being to that epitome of accuracy, the UK tabloid Daily Mail (for context, I heard the Mail got a science story right once, but I’ve never been able to verify that). The article quotes people making a lot of breathless claims, like the Sun “reacted” to the sphere, or that it might be a “rouge [sic] planet”. A photo caption claims it’s a huge blue sphere and it’s “mystifying scientists”.

Sure. Except no.

I’ll explain in a sec, but first things first: How did this all start? Apparently, a woman named Pamela Johnson posted about this on Facebook, which got the ball rolling. It’s an image from NASA’s STEREO A spacecraft, one of a pair of probes orbiting the Sun. They were launched in opposite directions, designed to take images of the Sun from different angles, and provide a more global view of our tempestuous star. STEREO B has been having some issues lately due to hardware problems, but STEREO A is still ticking along, on the other side of the Sun from the Earth.

The image is weird, certainly. Johnson makes some, um, unorthodox claims about it involving New Age things that I won’t delve into.

Being more of a sciencey persuasion, I looked at the image carefully to try to figure out what I was seeing. I went to the STEREO image search page and found images from that date. Quite a few show the anomaly, while others don’t. At the top of this article is a cleaner shot of one of the images, taken on Nov. 17, 2016, at 17:29 UTC.

The two bright spots with vertical lines going through them I recognized as planets right away; planets are bright and overload the detectors a bit, bleeding light into neighboring pixels (this is called blooming and happens all the time in digital detectors, including spacecraft that observe the Sun; UFO hunters and Planet X conspiracy theorists tend to go bananas over such things). Incidentally, the planet to the lower right is Venus, and the one closer to center is… Earth! Because STEREO is on the other side of the Sun, the Earth is in its field of view. So that’s us! Cool.

As for the giant blue ball, that’s no mystery: It’s the Sun. I mean, clearly that’s what it is. The real question is why it appears to be superposed on the image of the planets.

Briefly, the image comes from an instrument on STEREO called the Sun Earth Connection Coronal and Heliospheric Investigation, or SECCHI. This has several detectors on it, including the Heliospheric Imager, or HI, which is a visible-light camera designed to look at the Sun’s corona, its faint atmosphere that streams into space. The image showing the two planets is from H1.

But the image of the Sun is definitely not in visible light. I knew right away it was either in ultraviolet or X-ray; the Sun writhes and fumes under its intense magnetic fields, and that’s best seen at those higher energy forms of light.

So why is there a visible light image combined with a UV one? Instead of supposing there are higher dimensional beings warning us about the oncoming Trump presidency, I did something truly silly: I contacted some scientists involved with STEREO who might know the actual answer. Karen Fox, Joe Gurman, and Alex Young at NASA’s Goddard Space Flight Center quickly got back to me. The answer is pretty simple, and makes perfect sense: Sometimes, the image processor onboard STEREO gets overloaded, and becomes “confused”. When that happens the images get corrupted, and sometimes two images from two different cameras get combined.

That’s precisely what happened here. The HI image was combined with one from the Extreme Ultraviolet (aha!) Imager, producing the bizarre image seen. EUVI takes images at various wavelengths of UV light (think of them as different colors), and this one is from a 17.1 nanometer image, which is where highly energized iron atoms emit. These trace the Sun’s activity well, and that’s why the image shows so many interesting features. The bright spot is where magnetic activity is especially intense, most likely due to a sunspot.

I found an EUVI image from around the same time as the weird one. The features were very similar. I rotated and flipped it to match the HI image (different cameras have different orientations and readout directions); here they are side by side.

Voilà.

Not-so-incidentally, each wavelength seen by EUVI is displayed using a different color to help distinguish them. They aren’t true colors —our eyes can’t see in the ultraviolet— but done as a way to easily identify each wavelength and keep them straight. The EUVI 17.1 nm images are colored blue. So it’s not a “huge blue sphere”. It’s a huge ultraviolet one that’s been colored blue.

AKA the Sun.

So there you have it. No conspiracy, no higher power. Just a glitchy computer.

Of course, another way to think about it is this: It’s a glitchy computer in a space probe launched in 2006 on a huge rocket that took it around the Earth’s orbit to the other side where it uses a complex and sophisticated suite of powerful scientific instruments to track our Sun in wavelengths invisible to the human eye so that we can better understand what it’s like to live in the outer atmosphere of one of the Universe’s most mighty denizens: a full-blown star.

Reality is WAY cooler than nonsense.

Categories: Astronomy Headlines

What the Heck Is Going on at the North Pole?

Mon, 11/21/2016 - 05:45

I’ve written quite a bit over the past few years about the death spiral of sea ice at the North Pole. Every year the amount of ice goes up and down with the seasons, growing in winter and declining in summer. But, on top of that there has been a trend downwards, such that year by year we see less ice all the time.

Because of that we tend to see records set nearly every year. For example, this year in March the Arctic sea ice reached its maximum extent*, but it was the lowest maximum extent ever seen since satellite records began in 1979.

Starting in September every year the ice begins to reform, growing to a maximum. It reached that point on Sep. 10 this year, when it had the second lowest extent on record. After that day, though, it started to grow again.

Except… it didn’t. It started to, but then in early October the growth just stopped. A couple of weeks later it started to rise again, but stalled a second time in late October. In the weeks since then the amount of ice has actually fallen a bit. We are now at record low ice for this time of year, and have been for weeks.

Mind you, it’s winter up there. The Sun shines at most a few hours a day at the southern edge of the Arctic Circle right now. Yet temperatures in the Arctic are soaring; in mid-November it was an average of a staggering 22° Celsius, or 40° Fahrenheit, above normal.

Holy cripes. What the hell is going on?

The obvious answer is: global warming. Like I said, as time goes on, average temperatures go up, and amount of ice decreases.

But there’s a less obvious but more important answer, too. And that is: global warming.

That’s not a typo. The proximate cause of the temperature spike has been a weak jet stream. That blows around the pole, and generally keeps the cold air up there and the warm from the south away. But the jet steam has been weak lately, and warm air has been able to push up into the Arctic and keep temperatures up.

So why is the jet stream weak? Yup. It’s global warming. One thing that powers the jet stream is the difference in temperature between mid latitudes and the more northern ones. As the planet warms, that difference has fallen (the Arctic warms faster than lower latitudes do), and that has weakened the jet stream.

But there’s more. Because the planet is warming, the sea surface temperatures are going up as well. Water that’s usually frigid in October (like the East Siberian and Barents Seas) has been warmer, so ice growth is slow.

There’s a subtle thing happening here too that’s important. It’s not just that we’re seeing slower ice growth, but the high temperatures are actually melting old, thick ice as well. So it’s not just the extent that’s dropping, it’s the volume as well. That’s important because thin ice comes and goes, melting faster in the summer, but the old thick ice should be here to stay. That’s no longer the case; we’re losing that too.

Here are two videos showing that. The first, from NASA, shows a map of Arctic ice over the years:

The second, by Andy Lee Robinson, shows this even more clearly using a graphical approach:

I have to add that another graph has been making the rounds, showing the total global sea ice extent. It’s troubling as well, but it comes with a caveat. Here’s the graph:

This follows the amount of sea ice at both poles, arctic and Antarctic. It’s not really a good way to understand what’s happening because the physical conditions at the two poles are very different, and the amount of ice at each is ruled by different circumstances. Combining them just confounds all this.

Right now it’s approaching summer in the southern hemisphere, and we expect Antarctic ice to decline. However, even so, it’s falling faster than usual, and the extent there is lower than normal, too.

I include this graph because so many people are talking about it, and it’s important to understand that scientists don’t usually combine the two poles into one graph that way.

However there’s a second point to make as well. Whenever I write about arctic ice, a herd of climate change deniers converge in the comments and on social media, barking about how Antarctic sea ice is unchanged or even on the rise. But —shocker— that’s crap. The two are unrelated; Antarctic sea ice tends to be relatively steady year to year, and, as you can see, despite that it is pretty low right now.

And they also ignore the fact that arctic ice has been steadily decreasing for decades. Well, steadily until the past few weeks.

It’s possible that the boreal ice will get its act together and start growing again this season. It’s also possible it won’t. Time will tell.

But time is not on our side. It’s entirely possible we’ll see our first ice-free arctic summer in just a few decades. Not centuries, or even a century. But maybe by 2040.

The reason this is a concern is two-fold. One is that as the northern ice melts, it dumps a lot of fresh water into the oceans. This changes the salinity of the oceans, and that changes how the water flows from the Arctic to the equator and back again. This heat exchange powers a lot of our climate and weather, so having this break down is, in a word, terrifying.

Second, the Arctic is our climate canary-in-a-coal-mine. Because it’s so sensitive to warming, studying it shows us what we’re in for as our planet inexorably heats up.

I won’t spin this: This is not good news. As I wrote recently, all is not lost, and there are still things we can do to help mitigate global warming.

But with Donald Trump in office, and him loading his cabinet with climate change deniers, I worry very much over what the next few years will entail.

* “Extent” is a term climate scientists use, and it’s a little different than just the area of the ice. When they measure the ice they divide the area into regions, and if a region is more than 15% ice they say it’s ice-covered.

Categories: Astronomy Headlines

This Is NOT the Milky Way. Except It Is.

Sat, 11/19/2016 - 06:00

In 2013, the European Space Agency launched the Gaia astronomical observatory. Its mission: Map the positions and motions of a billion stars in our galaxy. Yes, a billion.

The first data release was pretty cool, and some of the early release images were lovely as well. In 2015 the ESA released a nifty map of the Milky Way generated by Gaia data, but it wasn’t actually a photograph: They used engineering data from the observatory itself to map out where stars in the sky were, with denser patches mapped as brighter. Because the image is large and the resolution high, it looks like a photo.

They recently released a cleaned-up version of that map, which I’ve displayed above. This one is smoother looking and they used a different color scheme, but it still does the same thing: What you’re seeing is not an actual photo, but a map of where stars are on the sky.

It uses a galactic projection; the Milky Way is a flat disk, and we’re inside it. Because of that we see the disk spread out as a thick line across the sky. This image maps that so it goes across the middle of the frame, and the direction toward the galactic center is in the center of the frame as well.

You can see lots of features: The Milky Way really is pretty flat, for one. There’s a central bulge, decorated with ribbons and festoons of dark, light-absorbing dust, blocking the stars behind them. You can also see the two small satellite galaxies, the Large and Small Magellanic Clouds, to the lower right of the Milky Way’s disk. Various other patches are from globular clusters orbiting our galaxy.

I describe all these features in Crash Course Astronomy: The Milky Way:

Gaia is pretty amazing. It has ten primary mirrors, each about 1.5 x 0.5 meters, which collect starlight and focus them into two different cameras. The positions of the stars are measured with ridiculous precision, about 20 microarcseconds. An arcsecond is an apparent size on the sky; the Moon is 1,800 arcseconds across, for example. A microarcsecond is a millionth of an arcsecond, so Gaia will map the sky with incredible accuracy*.

This allows it to measure parallax, the apparent change in position of a star as the Earth moves around the Sun in its orbit (why yes, of course I have another Crash Course Astronomy episode which explains this in detail). This means Gaia will map not just the positions but also the distances to those billion stars it sees. Moreover, it can take spectra, breaking the light into colors. Astronomers use that information to find out what kinds of stars they’re seeing, they’re chemical composition, and more (yup: See Crash Course Astronomy: Light for more on that).

All in all, Gaia will be a huge resource for astronomers for many decades to come. And if all this hasn’t boggled your mind yet, think on this: Although it will map a billion stars, Gaia will only see less than one percent of all the stars in our galaxy.

Galaxies are mind-crushingly vast collections of stars. We’re only scratching the surface with Gaia… but how else will we ever get to the fun inner parts if we don’t get through the surface first?

* Correction, Nov. 19, 2016: I originally wrote that a microarcsecond is a billionth of an arcsecond, not a millionth. 

Categories: Astronomy Headlines

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