Bad Astronomy Blog

Goaturday

9 hours 12 min ago

Is Caturday still a thing? I don’t care, because it’s now Goaturday.

That is my goat, Jack Burton.* He is one of four goats we have chez BA, the others being Sam, Batman, and Clayton Forrester. They are all fun and cute and adorable, and you can find lots more pictures of them on my Instagram feed (for all my social media links, go to about.me). For example, here is video of me feeding them apples, and here is Jack yelling, “What what?”

I’m on travel right now and my wife sent me this photo of Jack to remind me of some of what I’m away from. It makes me homesick, but it also makes me smile that he’s such a dork, chewing with his mouth open. They’re all dorks and I miss them. But look at him! Look!

When I get home I will scratch them all on their heads and pat their bellies and they will in turn belch in my face and poop everywhere, because they are goats. That’s all as it should be.

*Because I know someone will ask: Here ya go.

Categories: Astronomy Headlines

Venus and Jupiter Kiss This Weekend

Fri, 08/26/2016 - 06:00

There’s a real treat in the sky over the next few nights: Venus and Jupiter will be very close together. How close?

Very, very close. Closest approach (what astronomers call the appulse, but is more colloquially and commonly called a conjunction) will be on Saturday at 22:00 UTC (18:00 Eastern U.S. time), and at that time they’ll be an incredible four arc minutes apart. That’s only 1/15th the width of the full Moon on the sky! In fact Jupiter appears half an arc minute across, so Venus will only be about eight times Jupiter’s diameter away!

That’s close. Close enough that they’ll barely be far enough apart to separate by eye. The simulated shot at the top of this post shows the view through a telescope at closest approach; you can see Jupiter, its moons, and Venus all together nice and snug.

Now for the not so great news: The two are only a little over 20° from the Sun, so they’ll be low over the western horizon by the time the sky gets dark after sunset. The good news though is that both are so bright they’re visible even while the sky is still bright, especially in binoculars. If you know where to look you can actually see them when the Sun is up, too! But that’s for folks with some experience; do NOT search for them with binoculars; the Sun is so bright it can physically hurt your eyes if you accidentally glimpse it through them.

The conjunction is cool not just because it’s pretty (and it is). It’s also rare. The planets orbit the Sun, moving at different speeds. They all stay in pretty much the same plane—it’s usually called the plane of the solar system—and we’re in it too, so the planets move more or less along the same path in the sky. But not exactly the same path, so they pass each other at various distances. A close pass is pretty rare and in fact this is the closest any two planets get all year.

It’s also cool because of the physical reality of what you’re seeing. Venus orbits the Sun closer than Earth, and it’s on the other side of the Sun right now. So you’re looking past the Sun (which is 150 million kilometers away from us) to Venus, which is about 230 million kilometers away. Jupiter is a staggering 950 million kilometers away!

What amazes me is that even though Jupiter is more than four times farther away, it still appears three times bigger than Venus. That’s because Jupiter is ridiculously huge, a dozen times the diameter of Venus.

And one other thing. I’ve written about Juno, the spacecraft currently in orbit around Jupiter. It currently takes 53.5 days to go around Jupiter once and is screaming back toward Jupiter right now. On Saturday, the same day as the conjunction, Juno reaches perijove, its closest approach to Jupiter—just 4,000 kilometers above the cloudtops! After that it heads back out, moving away from the giant planet once again. In October, it’ll fire its engine and lower the orbit, moving it into its science orbit.

My friend Emily Lakdawalla at the Planetary Society has written about Juno many times, and describes an amazing video showing Jupiter as seen from the spacecraft as it moved away from Jupiter nearly two months ago. Here’s the video, but go read Emily’s write-up, because (as usual) it’s great.

I love how Jupiter is half full, a view we don’t get from Earth.

But our view this weekend (and really for several days) of Jupiter will be amazing, and that’s a pretty good consolation prize. I hope you have clear skies and an unrestricted view of this wonderful event.

Categories: Astronomy Headlines

Follow-Up: Just How Hot Was July 2016?

Thu, 08/25/2016 - 06:00

The other day I posted an article about how ridiculously warm July 2016 was globally. Like every month for 10 months in a row, it was the hottest such month since records have been reliably kept (starting in 1880).

This happens so often now that I just repost the same article, with the dates and numbers updated. That’s one way you know the planet’s getting hotter: When every record hot month or year is the month or year you’re in, it’s getting hotter.

But there’s more to this. July is generally the hottest month globally in the year, because it’s summer in the Northern Hemisphere, which has more land mass than the Southern one. Land heats up faster than ocean, so northern summer adds more to the overall warmth. This means July was not only the hottest July on record, but the hottest month on record as well.*

The plot at the top of this article shows that, with July clearly in a class by itself. It also shows that 2016 is hugely favored to be the hottest year globally on record, beating the previous two record holders: 2014 and 2015 (and please read the second paragraph above again if that helps you put this in context).

But it’s worse than that. Records being broken is one thing, but even then you have to look at the trend.

There are various ways to do that, but our brains are keyed to see motion. To that point, here’s an animation of that same graph above, showing each year’s monthly temperatures since records began:

That animations shows temperature anomalies, the deviation from some average (in this case, the annual average over the date range of 1980 to 2015). As you can see, the yearly graph shifts up and down somewhat randomly until just after the mid-20th century, when the average just starts going up. That’s warming. And this plot downplays the data somewhat, because the average is taken so recently, when global warming already had us in its grasp. Had an earlier average been used (say, 1951–1980, which is a commonly used range) then the scale on the left would show higher numbers.

Deniers downplay all this. They say that it’s been hotter in the past, and that the climate changes all the time. Like so many anti-science claims, that’s a tiny parcel of truth surrounded by a huge dollop of crap. Of course it’s been hotter in the past. Of course climate changes. But the rate of global warming we are seeing now is unprecedented, faster by a huge margin than we’ve seen for more than 10,000 years.

That’s why this is scary. It’s how fast the temperature is climbing. The effects we are seeing now are getting pretty obvious, too. Watch this NASA animation of the Arctic ice melting based on satellite observations, starting from its maximum extent in March 2016 to August (note that the minimum extent won’t be reached until September):

While 2016 is unlikely to set a record low extent of ice, every year for the past decade has been far, far below average. How long will it be before we see an ice-free Arctic summer? A few decades. Not centuries, but decades.

I could go on and on, and believe me I have. It’s stunning that people will still deny the reality of global warming, and ignore the slap-in-the-face effects it’s having on our climate. We know this is happening, and politicians fiddle while the Earth burns.

And as I have also said many times: It’s not too late, and there are things we can do. If you’re a U.S. citizen, where this political problem may be biggest, (politely) let your representatives know you care about this issue, and when November comes, vote.

We all live on this planet, and it’s the only one we’ve got. Let’s end this uncontrolled geoengineering experiment while we still can.

*When I tweeted about it, I meant to say “No human alive today has lived through a hotter July. Ever,” but forgot to add the words “alive today.” A lot of pedants jumped over me about that, when still the meaning was clear in the article. I accept I misphrased it, but it would be kinda nice if people actually clicked a link and read an article before going full denial on the internet. A man can dream.

Categories: Astronomy Headlines

Astronomers Discover a New Planet Orbiting the Closest Star to the Sun!

Wed, 08/24/2016 - 10:00

There’s no other way to phrase it. This is HUGE news: Astronomers have found a planet orbiting the Proxima Centauri, the closest star to the Sun!

Holy wow. Seriously. Wow.

Before I get into details, let me sum up what we know:

The planet, called Proxima Centauri b or just Proxima b (exoplanets are given their star’s name plus a lower case letter in order of discovery, starting with “b”), orbits Proxima every 11.2 days. It has a mass of no less than 1.3 times the Earth’s, so if it’s rock and metal like Earth it’s only a bit bigger. It’s a mere 7.3 million kilometers from the star—a lot closer than Earth's distance from the Sun of 150 million kilometers!—but Proxima is so faint and cool it receives about two-thirds the amount of light and heat the Earth does. That means that it’s in Proxima’s habitable zone: It’s possible (more or less) that liquid water could exist on its surface.

Did I mention wow? Because wow.

The European Southern Observatory put together a nice video about the discovery:

There’s some backstory here, and it’s very cool. Proxima Centauri is only 0.14 times the diameter of the Sun and 0.12 times its mass. Its surface temperature is much lower, so it’s cool and red, what we call a red dwarf. It orbits a binary star called Alpha Centauri, made of two stars more similar to the Sun (so the whole system is a trinary star). Proxima is pretty far out from the pair, about 0.1 light-years or so (a trillion kilometers), about 200 times farther than the distance of Neptune from the Sun. So it’s nearly out by itself in space, barely bound to the binary.

The Alpha Centauri binary is easily visible from Earth’s Southern Hemisphere, though they look like one star at their distance of about 4.3 light-years, and are among the brightest stars in the sky. Proxima, even though it’s closer to us, is so intrinsically dim that you need a good pair of binoculars to see it at all.

Because it’s the closest star to the Sun, astronomers have looked at it for decades to see if there’s any evidence of a planet. There have been false alarms over the years, all eventually shown to be errors.

But this time it looks like it’s very much real. The difference is the quality of data, because our technology and techniques have improved mightily recently. Using two different cameras on two different telescopes, the astronomers divided the light from Proxima into a spectrum showing many individual colors. They looked for subtle and periodic changes in the spectrum that would be due to a planet orbiting the star. As the planet moved, it would tug on the star; Proxima would make a little circle as the planet made a bigger one. This creates a Doppler shift in the spectrum, which in principle can be measured.

The faster the planet orbits, the bigger the shift, and usually the easier it is to detect. Proxima b, though, moves around its star at a leisurely one or two meters per second; if you walked briskly, you could outpace it! That's a very small signal.

But the eyesight of the cameras was sharp, and the ability of the astronomers to tease out the signal greater. By using other telescopes to observe the star, they were able to account for any change in the star’s brightness that could masquerade as a planet, confounding the results. In the end, the signal from the planet’s motion came out pretty clearly. I have to admit, it looks pretty solid to me.

That’s important to me: A few years back a planet was announced orbiting one of the stars of Alpha Centauri, which was very big news. But later it was found to be a spurious signal, and in reality no planet was seen. Planet discoveries get retracted every now and again, especially ones where the signal is faint. In this case when I heard the news I was pretty skeptical, but after reading the paper it looks good to me. I’m satisfied the planet is real.

There are some caveats, though. For one, we can’t know the true mass of the planet. If we see the orbit edge-on then it has a mass of 1.3 times the Earth. But if the orbit is tipped, the mass has to be greater to cause the star to wobble as observed, and if the orbit is tipped by 45°, say, the planet’s mass has to be 40 percent bigger. If it’s tipped more, the planet has to be even more massive.

We’re not sure of the shape of the orbit. It might be elliptical (aficionados of exoplanets take note; the eccentricity is no more than 0.35), or it might be circular. But either way, it’s at the right distance from Proxima that, given reasonable assumptions about the planet’s composition, it could have liquid water on its surface. This calculation has a lot of caveats—its temperature without an atmosphere would probably be around -40° C, but Earth’s average temperature without the greenhouse effect is only -15°. So yeah, cold, but if it has enough CO2 or other greenhouse gases in the air (assuming it even has air!), it could be clement there.

If so, that makes it not just the closest exoplanet known, but the closest potentially habitable one known.

Again: wow.

Mind you, we know nothing of its composition, or even its size. It may be completely uninhabitable, or it might be Eden. There’s no way to know. So be cautious here: It’s likely to be Earth-size, but we don’t know if it’s Earth-like.

Either way, it’s more than 40 trillion kilometers away, so we’re not going there any time soon. The fastest spacecraft we’ve ever launched would take many tens of thousands of years to get there. Don’t pack your underthings just yet.

Still, this is terribly, terribly exciting. We’ve only known for sure about the existence of exoplanets—worlds orbiting alien suns—since 1992. The first found were orbiting a dead star, a pulsar. The first planet orbiting a Sun-like star wasn’t found until 1995, and in the next two decades we built telescopes dedicated to looking for them, and as of today we know of over 3,000 such strange, new worlds.

Quite a few are Earth-size, and fewer possibly Earth-like. Still, we can make estimates that there are billions of Earth-size planets in the galaxy.

And now we know that it’s possible that the nearest one is, on a cosmic scale, right next door.

People say that it’s a curse to live in interesting times. But with science, it’s not. It’s amazing.

Categories: Astronomy Headlines

Super Slow Motion Beauty of SpaceX Rockets

Tue, 08/23/2016 - 06:00

Every now and again, I think, everyone can use a little eye candy. In this case, though, it’s more than that: It’s also hope for the future. Watch this high-speed footage of SpaceX rocket launches and landings, and see what the future looks like now.

So cool.

The first part shows the launch, booster separation, and landing of the first stage booster from the launch on May 4, 2016 of the Japanese communication satellite JCSAT 14 on a Falcon 9 rocket. The odd fireworks display in that section of the video is the interplay between the plumes from the first and second stages as they separated.

The landing of this particular booster was a big deal: Although it was the third successful landing (and the second at sea), it was the first time it was done from a launch designed to put a satellite into a geosynchronous orbit, which is much higher off the Earth than a low orbit, and required a higher than usual velocity. Landing this booster was therefore particularly difficult, and marked a big milestone for the company.

The next landing seen in the video was an even bigger milestone: It was the first successful vertical landing of a Falcon 9 first stage booster, accomplished on Dec. 22, 2015 (it was Dec. 21 Eastern time) for the ORBCOMM-2 launch.

I love that part of the footage. The booster used one of the nine Merlin engines to slow its descent, and you can clearly see the single engine burning while the other eight are dark, the dance of the flames playing over them as its blown back up toward the rocket’s back end.

The final part of the video shows the first stage rocket landing back at Cape Canaveral after launching a Dragon capsule to the International Space Station on the CRS 9 mission, launched on July 18, 2016. Again, you can see the single engine burning as the booster lowers itself to the pad. The landing legs are folded up during launch, and are deployed on the way back down; you can see the unscorched sections of the booster showing where they were stowed until needed at landing.

Even though the footage is shot in high speed and therefore looks like it’s in slow motion, I suggest playing it back at 0.5 or even 0.25 times the normal speed (on YouTube, click the gear icon on the lower right, then change the speed setting). You can clearly see the play of the flames and the detail of the rocket engines. It’s really astonishing.

SpaceX is getting very, very good at landing the first stage boosters, and has been test firing them to see how they might perform when reused. This will lower the cost of launch by a large margin, making access to space much cheaper. I’ll add that Blue Origin, Jeff Bezos’s rocket company, has made several suborbital launches and landings with the same rocket, and will be soon attempting orbital launches with a next generation rocket. Several other companies (like Sierra Nevada and Boeing) are also on their way to making spacecraft that will eventually be used to carry supplies and people into space.

The future. We are very nearly in it.

Categories: Astronomy Headlines

Global Warming Has Now Made the Northwest Passage a Thing

Mon, 08/22/2016 - 06:00

More than a century ago, explorers dreamed of a Northwest Passage, a route from the Pacific Ocean to the Atlantic by plying the waterways north of Canada, threading through the Canadian Arctic Archipelago, huge icy islands north of Canada. Such a trip was fantastically dangerous and well-nigh impossible, since in the winter and even most of the summer, the waterways were either frozen solid or littered with huge blocks of ice.

Roald Amundsen was the first to successfully make his way through. It took him three years in a small ship starting in 1903, and included getting stuck in ice three times.

Fast-forward. On Aug. 16—just days ago—a 250-meter-long, 1,070 passenger cruise ship, the Crystal Serenity, set sail, and is expected to make its way through the Northwest Passage in just eight days.

How can it do so? Global warming.

Over the past few years, the Arctic has warmed so much that the fabled passage has become a reality. The ice melts so much in the summer that it’s not only possible for ships to make their way through the archipelago, but it may be commercially viable to do so.

To be clear, quite a few ships have made the passage since 2007, the first year the ice had melted enough to make it far easier to cross. But it’s been a struggle, and bigger ships have a more difficult time. On average, every year it gets easier as the ice melts away due to the increased heat in the Earth’s northern regions.

Deniers of global warming will make sidetracking claims, talking about how Antarctic ice is increasing (it isn’t), or other non sequiturs (note: In a massive irony, even the fossil fuel companies funding so much climate change denial accept that the Arctic is melting, and are scrambling for rights to drill for oil there). The reality is that the Arctic is warming at a rate twice as fast as the rest of the planet—temperatures in the Arctic have been more than seven degrees Celsius higher than average—and the ice up there is melting so fast that it’s been called a “death spiral.”

And understandably so. Watch:

There are two ways to measure Arctic ice: extent and volume. Volume is obvious enough; it’s literally the volume of ice. Extent is similar to the area covered by ice but is technically defined as the amount of area covered by more than 15 percent ice in a given region. Both have decreased dramatically in the past couple of decades, but the extent is more important for the Northwest Passage. Warmer summers mean the ice doesn’t freeze as much in the winter, so it’s thinner and melts more easily the next summer. That makes getting through with a ship easier.

The record low extent for Arctic ice was in 2012. That was an unusual year; an ice dam collapsed, allowing warmer waters to move north, melting ice far more than normal. Arctic ice hits its minimum extent in September every year, and this year is on course to be among the lowest ever seen.

If you click that graph, you’ll be taken to an interactive version. Click the years to see the ice extent over time. You’ll note that 2012 was indeed the record low, but every year over the past 10 years has been far, far below average.

That’s because of global warming. Experts predict we’ll see our first ice-free Arctic summer around 2040, and given the downward trend of ice extent, that sounds about right. Mind you, this is inevitable; even if we stopped burning fossil fuels today, stopped pouring carbon dioxide into our air, the damage is already done. Warming would continue for decades, perhaps centuries, and the Arctic ice will melt. The same is true for Antarctica; the trajectory of warming means that the western glaciers of that continent are almost certainly doomed to melt away no matter what we do now.

It’s not too late to save our planet, though. There are things we can do. Enact a carbon tax, for one. Switch to renewable energy for another, which is completely doable.

And third? Vote science deniers out of office. They inhabit not only the U.S. Congress but also political seats all over the world.

When it comes time to vote, vote. Climate change is important enough to make it a one-issue election, but some people feel that’s not enough to sway them. But really that’s a matter of framing. Chances are those who deny the reality of climate change deny lots of other science, too. When that one issue is reality itself, then damn straight this is a one-issue election.

Categories: Astronomy Headlines

The Day a Cloud Wore a Cheery Hat

Sat, 08/20/2016 - 06:00

Still, as I mused, the naked room,
The alien firelight died away;
And from the midst of cheerless gloom,
I passed to bright, unclouded day.

   —Emily Brontë, “A Little While, A Little While”

I’ve written many times about summer clouds in Colorado; moisture-laden air blows over the Rockies to the west, flowing to the east. The Midwestern plains butt up against the hills, and as the afternoon Sun heats them, warm air rises vigorously and meets the eastward-flowing wave. Within a few dozen kilometers, this creates towering pillars of massive, wet air, punching upward into the sky.

A cumulonimbus cloud is born.

The drama and sheer energy of these storm clouds is terrifying and awe-inspiring. But even in their brute force, a delicate veil can be created.

That photo shows a cumulonimbus cloud getting its convection on to the east of where I live in Colorado. You can see several columns of rising air creating the cauliflower puffs in the towers. But two of them, in front of the two in the background, are capped: They have a thin layer of cloud draped over them, looking like a hand pushing upward through a sheet.

That layer is called pileus, named after a hat worn by ancient Greeks and Romans. As warm air rises rapidly, it pushes the moist air above it which then cools. If it cools past the dew point, the water condenses to form the thin cloud (sometimes the water will form ice crystals, producing a similar effect).

I never saw one until I moved to Colorado, and I remember well sitting outside and seeing it for the first time. I knew right away what must be causing it, and a quick online search confirmed it. Science! I knew enough about how air moves to guess at the solution, and was pretty pleased with myself for getting it right.

Pileus clouds tend to be ephemeral, dissipating quickly as the convecting air blows upward. I had just enough time to see this pair, run outside, and snap a few shots. Within minutes they were gone.

A good chunk of science is being at the right place at the right time to see something briefly. I suppose the same is true for art, and when it comes to clouds—as well as so many other things—they are both at the same time.

As for the quote at the top of this article, normally I wouldn’t be so cheeky as to disagree with Ms. Brontë, but in this case I must. Clouds are a glimpse into the mighty power of fluid dynamics, complicated equations made real and actual and gorgeous, painted across the sky. And given how dry it’s been here lately, a good rain cloud would be cheerful news indeed.

Other articles I’ve written talking about pileus clouds:

Categories: Astronomy Headlines

A Cosmic Flower Blooms and Sends Its Seeds Into the Void

Fri, 08/19/2016 - 06:00

NGC 7129 is a fascinating and terribly lovely object. It’s a stellar nursery, a site of active star formation, buried deep within an invisible cloud of very cold molecular gas and dust. Luckily for us, a handful of massive stars were born near the edge of this cloud, carving a blister in its side and exposing their fierce light and beauty to us:

Holy wow! That image is a combination of observations using the giant 10-meter Subaru telescope, the 0.81 meter Schulman Telescope (from my old friend Adam Block), and a 35 cm telescope, all of which were processed by Robert Gendler and Roberto Colombari.

It’s a spectacular photo to be sure, but there’s a lot of science in it, as well as a surprise.

Remember, what you’re seeing is a small part of a much larger complex of gas and dust, with only this local volume illuminated by the stars within. The brightest, most massive stars being born there are blue, and the blue glow you see is light reflected and scattered by grains of dust, so we call it a reflection nebula. That’s a sure sign you’re seeing young stars; blue stars don’t live long, so they must be young, and the regions where they’re born are typically choked with thick dust clouds.

Some of the dust is so thick it blocks the light coming from behind it, which is why there’s a collar of blackness on the lower left side of NGC 7129, separating the main nebula from the circular blue reflective patch caused by another star. The young stars—only a few million years old at most, a tiny fraction of the Sun’s 4.5 billion year age!—can also focus twin beams of matter blasting outward from their poles as they form. This slams into the material around them, forming those small curved arcs you can see here and there in the nebula. Those are like the bow waves coming off ships as they ply the ocean.

What amazes me most about this image though are those pinkish tendrils to the upper right. Gendler notes they’ve never been seen before! I searched the professional journals and see no mention of them, which supports that claim. I may have missed something, I’ll admit, but given what they mean, I’d think someone would have mentioned them if they’d seen them in the past.

I can’t be 100 percent sure, but I strongly suspect this tendrils are literally a blowout: gas flung outward by the newborn stars, accelerated to high speeds, blasting out and piercing the thick veil of gas and dust surrounding the stars. It’s almost literally like a popping balloon, with the gas inside flowing out of the hole.

We’ve seen blowouts in other nebulae (such as Sharpless 2-308, the Swan Nebula, IC 5146, and the magnificent Orion Nebula … and yes, you really want to click those links), and even in the Milky Way galaxy itself. It means that the expanding gas from the stars found a weak spot in their cocoon, and exploited it. It’s interesting indeed that this occurs along the long axis of the bubble itself— either the stars are blowing out gas preferentially along an axis (which is likely) or the gas around them is thinner along that long axis, making the path easier for that gas to travel. It may be a combination of both.

In many images, NGC 7129 looks like a rose bud. In this case, the analogy is apt: It’s sending its pollen out into space, where it may help form new stars!

I hope that some professional astronomers will make use of this potential discovery and take deeper images and spectra of this nebula. At a distance of roughly 3,500 light-years, NGC 7129 is relatively close and easy to study. It’s part of a much larger and vastly more complicated array of clouds, and understanding any piece of it can lead to a better grasp of the whole.

Or, in this case, the hole.

Categories: Astronomy Headlines

So What Exactly Is an “Alien Megastructure”?

Thu, 08/18/2016 - 06:00

Last week, I wrote another article about KIC 8462852, aka Tabby’s Star, which is behaving very oddly indeed. It shows sharp dips in brightness that last for hours, as well as much longer ones that last for days (or longer) that indicate something is blocking a substantial fraction of the star’s light.

The most likely explanation is a cloud of dust with comets or asteroids embedded in it, which can cause the star to dim. However, it’s been maddeningly difficult to explain all the star’s behavior with this natural model. So, ever since its discovery and perhaps a bit sheepishly at first, astronomers have toyed with the idea that maybe what we’re seeing is evidence of an advanced alien civilization.

To be clear, no one is saying that’s what’s going on. But it’s a cool idea, and worth investigating at least a little. No radio signals have been seen from the star, though, and no other indication of aliens has been found.

Still, it’s fun to think about. The premise is that aliens are building huge panels of some kind around the star in order to capture more of its light to power their civilization (imagine it like the ultimate work of a Little Green Elon Musk). The idea of alien megastructures has been around a while, and has some merit as a thought piece.

Astronomer David Kipping, who studies Tabby’s Star, made a short video explaining all this simply and engagingly. He does a great job summing up what we know:

Kipping studies exoplanets and moons, and he and I agree strongly on this topic. It’s fun, it’s interesting, no astronomer really thinks this is what’s happening for sure, but it’s a compelling idea and well worth looking into. You know, just in case.

For more details and insight into what’s going on with Tabby’s Star, astronomer Jason Wright also made a video diving into the topic more deeply:

Back when all this started I had a long and very engaging conversation with Jason about it, and his take on it is grounded in reality and firmly based on evidence. His conclusion, like all the rest of ours, is that this is a highly intriguing star, its behavior is almost certainly natural, but it’s stimulating and perhaps even rewarding to look into more speculative explanations. They’re unlikely to turn out correct, but they stretch our imaginations and exercise our brains in a way that can be helpful in solving mysteries.

So, as usual, I’m still not saying aliens. But no matter what this turns out to be, it’s wonderful and stimulating, and just good old fashioned fun for a scientist to think about.

More about Tabby's Star:

Categories: Astronomy Headlines

Trump’s VP Mike Pence Wants to Teach That Old Time Religion in Public Schools

Wed, 08/17/2016 - 06:00

I’ve written a word or two about Donald Trump, as you might imagine, but not much on his vice  presidential pick, Indiana Gov. Mike Pence (except to say, unshockingly, that he is a climate change denier).

You know anyone picked by Trump to be his running mate almost certainly will have a problem with established science, of course, but it turns out Pence is also a young Earth creationist. And one with a lot of conviction about it, too. In 2002, while a congressman from Indiana, he gave a short speech on the floor of Congress denying evolution, and used quite a few misleading, if not outright false, claims.

The congressional transcript is worth a read, or you can watch him say it himself:

There’s a lot to debunk here, but let me point out some choice bits.

Charles Darwin never thought of evolution as anything other than a theory. He hoped that some day it would be proven by the fossil record but did not live to see that, nor have we [emphasis mine] .

Oh my, Gov. Pence, yes we have.

But no one is pointing out that the textbooks will need to be changed because the old theory of evolution taught for 77 years in the classrooms of America as fact is suddenly replaced by a new theory, or I hasten to add, I am sure we will be told a new fact.

When we learn new things in science we do generally say, “We’ll have to rewrite the textbooks,” a phrase used so much it’s actually a cliché.

And also it will be taught as fact if it truly is one, because that’s how science works. It grows and learns from new evidence. Don’t you think you should change your mind about a topic when new, contradictory evidence is brought forth?

And now that we have recognized evolution as a theory, I would simply and humbly ask, can we teach it as such and can we also consider teaching other theories of the origin of species?

Evolution is taught as a theory. And also a fact, because it’s both.

As for “other theories,” hang tight a moment.

Like the theory that was believed in by every signer of the Declaration of Independence. Every signer of the Declaration of Independence believed that men and women were created and were endowed by that same Creator with certain unalienable rights. The Bible tells us that God created man in his own imagine, male and female. He created them. And I believe that, Mr. Speaker.

Ah, the old “America is a Christian nation” gambit (and note that many denominations of Christianity have no problem with evolution). But that’s false. And that has nothing to do with whether evolution is true or not. And it is.

Then he said this:

And I also believe that someday scientists will come to see that only the theory of intelligent design provides even a remotely rationale explanation for the known universe.

Oof. Well, ID is not a theory, it’s just warmed-over creationism, and is now actually illegal to teach in public school because it’s religion, pure and simple. It was made illegal in 2004, two years after this speech, but ID was purposely constructed to be modified creationism since its inception (I'll note that Pence has made similar anti-evolution claims in the years since, too).

I feel that at the very least, a vice presidential candidate should uphold the Constitution, especially the First Amendment.

Not that Trump appears to have any desire to want to, either. That makes them quite the pair. I hope that come November, they can be unemployed together.

Categories: Astronomy Headlines

No, That’s Not a Picture of Antarctica from Space

Wed, 08/17/2016 - 06:00

I’ll make this short and (bitter)sweet: There’s a picture going around social media people claim shows Antarctica from space.

But it’s not; at least not really. It’s actually a visualization of data, a computer-generated image showing the extent of sea ice around Antarctica on Sep. 21, 2005.

The overall image is a composite from several different Earth-observing satellites, but the sea ice is from the AMSR-E detector on board the Aqua satellite. It uses microwaves to measure the extent of ice floating in the ocean. This was then mapped onto a computer-generated globe of the Earth from Blue Marble Next Generation (using different data from AMSR-E to estimate the ice color). The terrain map is actually from 2004, a year before the ice data were taken.

Perhaps it’s a subtle point. After all, many images from Hubble and other observatories are composites using separate images, sometimes in wavelengths invisible to our eyes! While this case is similar, it isn’t a snapshot taken by some orbiting camera; it’s more like making a map (like ones showing color-coded temperatures) created using various sources and then putting them together in a way that looks very photorealistic.

It's certainly beautiful, and even helpful both scientifically and getting people to see our planet in a different light. But it's not really a photo of Earth from space.

Perhaps too it’s not a big deal. It’s not a fake, or a hoax, or anything like that. But I do think it’s a good idea to understand the difference between an actual photo and a visualization. Under the assumption they’re real, unreal pictures are commonly passed around social media rapidly and without much critical analysis. I see this a lot (at the bottom of this article is a short list of just a few such widely-shared pictures I’ve written about), and I think it’s worth pointing out the difference between the real and the imagined.

I’m not trying to pick on people who do this, either. It’s natural to want to share something beautiful or exciting or awe-inspiring! And I’m glad people do, because images from and of space are beautiful and should inspire us.

But in my opinion, the real Universe is amazing enough without having to make stuff up about it. It’s important o be able to tell the difference between a photo depicting reality and a drawing meant to represent, and something I wish more people could do.

More articles about fake/hoaxed pictures or illustrations mistaken for reality:

Categories: Astronomy Headlines

March … I Mean April … I Mean May … I Mean June… I mean July 2016 Is the 6th … I Mean 7th… I Mean 8th … I Mean 9th… I Mean 10th Temperature Record-Breaking Month in a Row

Tue, 08/16/2016 - 06:00

N.B. If this article sounds familiar, it should. This has been happening so frequently I just copied the post for March April May June and updated it.

October. November. December. January. February. March. April. May. June. And now July.

For the

sixth seventh eighth ninth tenth month in a row, we’ve had a month that has broken the global high temperature record.

According to NASA’s Goddard Institute for Space Studies,

March April May June July 2016 was the hottest March April May June July on record, going back 136 years. It was a staggering 1.28°C 1.11°C 0.93°C 0.79°C 0.84° C above average across the planet. * The previous March April May June July record, from 2010 2014 2015 2011, was 0.92° 0.87° 0.86° 0.78° 0.74° above average; the new record beats it by a full tenth of a degree.

Welcome to the new normal, and our new world.

Note: NASA has created a short video describing its efforts to measure global warming, specifically pointing out that the first six months of 2016 have all been the hottest months on record of their kind:

As you can see from the map above, much of this incredible heat spike is located in the extreme northern latitudes. That is not good; it’s this region that’s most fragile to heating. Temperatures soaring to 7° or more above normal means more ice melting, a longer melting season, loss of thinner ice, loss of longer-term ice, and most alarmingly the dumping of billions of tons of fresh water into the saltier ocean which can and will disrupt the Earth’s ability to move that heat around.

What’s going on? El Niño might be the obvious culprit, but in fact it’s only contributing a small amount of overall warming to the globe, probably around 0.1° C or so. That’s not nearly enough to account for this. It’s almost certain that even without El Niño we’d be experiencing record heat.†

Most likely there is a confluence of events going on to produce this huge spike in temperature—latent heat in the Pacific waters, wind patterns distributing it, and more.

And underlying it all, stoking the fire, is us. Humans. Climate scientists—experts who have devoted their lives to studying and understanding how this all works—agree to an extraordinary degree that humans are responsible for the heating of our planet.

That’s why we’re seeing so many records lately; El Niño might produce a spike, but that spike is sitting on top of an upward trend, the physical manifestation of human induced global warming, driven mostly by our dumping 40 billion tons of carbon dioxide into the air every year.

Until our politicians recognize that this is a threat, and a very serious one, things are unlikely to change much. And the way I see it, the only way to get our politicians to recognize that is to change the politicians we have in office.

That’s a new world we need, and one I sincerely hope we make happen.

*GISS uses the temperatures from 1951–1980 to calculate the average. The Japanese Meteorological Agency uses 1981–2010, which gives different anomaly numbers, but the trend remains the same. Realistically, the range GISS uses is better; by 1981 global warming was already causing average temperatures to rise.

† You may have noticed that the actual temperature anomaly for each month over March through July appears to be dropping; 1.28 to 1.11 to 0.93 to 0.79 (though this month was bumped up to 0.84°). That may be due to El Niño weakening, but it’s hard to know over such a short time period. Even if the trend continues, I’d bet 2016 will be the hottest year on record.

Categories: Astronomy Headlines

Chemtrails? Nope.

Mon, 08/15/2016 - 06:00

I’ve spent a lot of time debunking silly conspiracy claims in my time. NASA faked the Moon landings, the Mayan calendar predicted the end of the world in 2012, a mysterious planet named Nibiru would wipe out life on Earth in 2003, the government created fake snow in Atlanta that wouldn’t melt and sorted when burned… I’ve even debunked government officials who claim other government officials are covering up conspiracies.

So when I say I haven’t bothered debunking chemtrails because they’re too goofy even for me, you can glean how I really feel about them.

Still, a handful of people are extremely devoted to the idea that the government is spraying us with chemicals from airplanes, and what you think are simple contrails are actually high doses of mind-altering (or climate altering) chemical compounds meant to keep us under control, I mean, come on, wake up sheeple!

Sigh.

In fact, when you see clouds coming from airplanes they really are just the product of condensation of water vapor. But why let facts get in the way of a good conspiracy?

Still, it’s worth trying. That’s why scientists from the University of California Irvine and the Carnegie Institute got together and researched the topic. They knew they wouldn’t convince the conspiracy theorists, but having a solid source of objective science might help inform the public discourse.

They surveyed hundreds of experts in contrails as well as those who study atmospheric deposition (how various chemicals fall to the ground from the air), presenting them with the evidence provided on various chemtrail websites (mostly in the form of photos of airplane trails and analyses of water and soil samples), asking them to evaluate it.

In the end 77 scientists reported back, and the results were not terribly surprising. 98.7 percent (76 out of 77) of the scientists said they had encountered no evidence of a secret large-scale atmospheric program (SLAP). Everything they saw on the conspiracy websites showed that what they were seeing was the natural consequence of airplanes flying around all on their own without government nefariousness.

Of course, the first thing you’ll notice is the one scientists who dissented. In that case, it’s hardly a smoking gun:

The one participant who answered yes said the evidence s/he had come across was ‘high levels of atm[ospheric] barium in a remote area with standard ‘low’ soil barium’.

In other words, they found some unusually high amounts of barium, which hardly supports the idea of wide-spread coverups of mind control techniques —and it sounds like the scientist in question was simply saying they can’t rule SLAP out, which is a far different thing than saying it’s real. When I can’t find my keys in the morning I can’t rule out that dinosaur ghosts hid them from me. It just seems a tad unlikely.

The research is actually rather interesting, and I encourage you to read it. But as the authors note, it won’t make a dent in the conspiracy theories. The first thing you’ll find out when you deal with people like that is that any evidence against them is part of the coverup. This is what I call a philosophical cul-de-sac; they’ve removed themselves from any possible evidence and criticism, and at that point I’ve learned to walk away. At least to walk away from them specifically; in some cases it’s worth pursuing the discussion with the public because they’re liable to hear about it, and a place to find actual facts and debunking is a handy thing to make available.

So I’m glad these scientists went to the effort, even though it may seem silly. Conspiracy theorists usually don’t make a big splash in real life, but if they get the ear of a politician time, money, and effort can indeed be wasted, sometimes on a big scale. Given how anti-science so many members of Congress can be, I don’t think there’s any idea too silly for them to not take seriously.

If Congresscritters think the Earth is cooling, that it’s only 6000 years old, that vaccines are dangerous, and that the existence of snow disproves global warming, then chemtrails don’t seem like that much of a stretch.

Categories: Astronomy Headlines

NASA Video Shows Meteor Shower… from Above!

Sun, 08/14/2016 - 06:00

Late last week marked the peak of the annual Perseid meteor shower, generally one of the most dependable shooting star shows of the year. You can usually spot about a meteor per minute streaking across the sky, leaving behind a momentary trail of vaporized rock that fades rapidly as it cools in the upper atmosphere.

Meteors burn up about 90 - 100 kilometers above the Earth’s surface. So what happens if you happen to be 400 km up, orbiting the Earth? What would it look like if you were looking down, toward the Earth, during a meteor shower?

It would would look like this:

That video was made on Aug. 10, 2016 using a camera on the International Space Station, specifically designed to look for meteors from above.

Did you see the two meteors in the clip? One happens at six seconds in, the other at 16 (the bright flash at the start of the video is lightning in a storm). It looks like they’re right over the surface, but perspective distorts that; they’re way up high.

Here’s a funny thing, too: At best only one of those meteors was from the Perseids! The meteors in a shower all appear to come from one part of the sky, as the Earth plows through the debris. It’s like driving through a rain storm, where the drops hit your front windshield because that’s facing into your direction of travel.

But the two meteors in the video are traveling at right angles to each other (one moves up, the other to the right). From the height of ISS all Perseids should travel in more or less the same direction, so at least one of those was not a Perseid! It’s possible neither were, but I can’t be sure without knowing the direction of the ISS movement, the exact time of the shot, and information like that. Still, the video is very cool.

It was made as part of a joint venture between the US Southwest Research Institute and Japan’s Planetary Exploration Research Center, part of a project called Meteor Composition Determination. Besides taking video like the one above it also employs a special type of spectroscopic device called a transmission diffraction grating. This acts like a prism, breaking up the light of the meteors into colors. The resulting spectrum reveals the composition of the meteoroid (the solid bit of debris that burns up); every element has a unique pattern of colored light it emits as it glows. Since these meteors come from comets, it’s a way of studying comets right here on (well, above) Earth.

I went out with friends to see the shower on Friday night. We didn’t see too many over the two hours we were there; maybe a dozen or so. To be honest, being north of Los Angeles I’m surprised it was dark enough to see any 9and the Moon was up too). But in this case it was just as much fun to hang out with friends as it was to watch the show. Meteor showers are wonderful, and I urge you to go out and see watch one sometime. The next good one is probably the Leonids in November, and then the Geminids in December. Mark your calendars!

Categories: Astronomy Headlines

When the Sun Never Sets

Sat, 08/13/2016 - 06:00

One of the funny things about living on a big spinning ball of rock and metal in space is that what you see depends on where you are.

Where I live, in Colorado, the Sun rises every day, makes an arc in the sky, then sets some time later. The same is probably true for you, too. What’s really happening is that we’re affixed to that spinning ball, and as it sweeps us around we move in a tilted circle, sometimes on the side of the Earth facing the Sun, sometimes facing away, but always in motion.

That view changes dramatically with latitude. If you go far enough north, then after the (northern) Vernal Equinox in March, the Sun never sets. The Earth’s North Pole is tipped toward the Sun, and even though it spins some parts of the Earth are in constant daylight, and remain so for months at a time.

I’ve seen time-lapse videos taken from cameras fixed to a tripod, showing the Sun moving around in a circle (or sweeping back and forth over the horizon). But what does it look like if, instead, the camera tracked the Sun’s path along the horizon as it moved?

Why, it would look like this.

That video, created by Witek Kaszkin, is pretty amazing. It sweeps along, moving horizontally as the Sun does too, keeping the horizon in the same place. As the Earth spins, the Sun bobs up and down over the course of a day, and also moves all the way around the sky. It’s a peculiar way of showing the motions, but I like how it shows the Sun’s change in altitude over the day, rising and sinking, but never setting …  it almost does, but in reality it just gets behind some tall, distant mountains.

The video was taken in April 2015, not long after the equinox, so the Sun does dip low to the ground, though never reaching it. The camera was at 77° north latitude, near the Polish Polar Station Hornsund at Svalbard, a few hundred kilometers east of Greenland (Kaszkin has another video from the same location showing a solar eclipse, which is really cool, and there’s a video of polar bears visiting the station, too).

If the Sun’s motion in the video confuses you, then I suggest reading a post I wrote about why the Sun never sets on the North Pole in summer, which has a more detailed explanation (and another cool video as well). The fun part of all this is how the motions and positions are all relative; the Earth is tipped, or the Sun is. The camera sees the Sun moving, or the Earth moving. The Sun bobs up and down, or really you do as you spin around the Earth.

What you see depends on your point of view, and if you change the way you see it you change what you see.

If there’s a life lesson to be had there, feel free to take it.

Tip o’ the axis to Greg Owen.

Categories: Astronomy Headlines

ORION. Holy Wow, Orion.

Fri, 08/12/2016 - 06:00

At a distance of 1,300 light years —just 13,000 trillion kilometers, which is close on a galactic scale—the Orion Nebula is one of the most magnificent objects in the sky. It’s so luminous that you can see it by eye even in mildly light polluted areas, and when you use binoculars you can tell it’s not a star, but something fuzzy and big, hinting at its true nature.

That nature comes into clarity when the nebula is photographed using a telescope. That reveals it to be an immense cloud of gas and dust, light years across, a factory for creating stars, colorful and spectacular.

But why describe it when I can show you? Behold!

This image of the Orion Nebula is one of the largest and deepest ever taken. It was done using the HAWK-1 infrared camera attached to the Very Large Telescope in Chile, an 8.2 meter telescope that can see celestial objects in extraordinary detail. This image is not exactly what was released by the European Southern Observatory originally; the observations were remastered by astrophotographer Robert Gendler to bring out more detail and to really shine a light (so to speak) on the phenomenal beauty of this immense stellar nursery.

There’s some important science lurking in this image, but there’s something I want to point out first. The glowing part of the nebula is actually just a small part of a much larger complex called the Orion Molecular Cloud. It’s a dense, cold cloud of gas and dust, invisible to the eye, and stars are forming in it. A clutch of stars happened to form near the edge of the cloud, and once they switched on after birth their intense radiation began carving enormous cavities in the gas, chewing away at the material in the cloud.

Because they’re near the edge, they eventually ate a hole on it the side of the cloud. In a sense they popped the bubble, blowing out the cloud at their location, which happened to be on the side of the cloud facing us. When we look at the Orion Nebula, we’re actually seeing a dimple or divot scooped out of the denser material. The lower density and much hotter gas filling that dimple glows brilliantly, creating the nebula we see.

This image actually shows that extremely well. Redder material is denser, and the blue glow suffusing the nebula is lower density, hotter gas, tracing the shape of the cavity. It’s an extraordinary glimpse literally inside the nebula.

You can easily see hundreds of stars clustered in the center of the nebula. In fact, that’s why these observations were made: To literally count the newborn stars there, determine their mass and luminosity (the amount of energy they emit), and use that information to determine just how stars are formed.

This can be hard to do, because at the faint end stars can be hard to see. Worse, objects with less mass than stars—brown dwarfs and planetary-sized objects—are so faint they fade to invisibility with distance.

But not to the HAWK-1 coupled with the VLT. This duo is so sensitive that all these objects can be found, providing a complete census of the stellar (and substellar) population.

The results are actually pretty intriguing. Before I reveal that, let me explain what the astronomers involved with this research were looking for.

The most obvious, brightest stars in the Orion Nebula are monsters, a hundred times the mass of the Sun and hundreds of thousands of times more luminous—put one of them in the center of our solar system and the Earth would be fried to a crisp.

Only a handful of these behemoths can be found in the nebula. In general, that’s always true: Massive, luminous stars are rare, and lower mass, cooler stars more common. Think of it this way: Take a rock, and hit it with a hammer. You get one or two big pieces, more medium sized pieces, and zillions of tiny shards. But the number of stars versus their mass tells you a lot about how they’re born, and so astronomers study this in as much detail as they can, and they call it the Initial Mass Function, or IMF.

Understanding it means understanding under what conditions stars are born, and that’s a key goal. That’s why the Orion Nebula was observed: It’s close enough that the faintest objects born there can be seen. Because of this, astronomers can be reasonably sure they’re seeing everything, and not missing the faintest objects, throwing off their results.

In general, out in the galaxy at large, the IMF peaks around stars with 0.25 times the Sun’s mass then drops off with lower mass. The big questions is: Does this trend continue, such that even lower mass objects like brown dwarfs and exoplanets* are rare?

For the Orion Nebula the answer is, “no”. The astronomers saw two peaks in the IMF, one around 0.25 times the Sun’s mass, and another at 0.025. In other words, Orion really likes making objects around those two masses, with fewer object at more or less mass than that.

That second peak is pretty surprising. It shows that Orion like to make substellar objects at ten times the rate previously seen in other surveys of the sky. Fully half the objects seen are substellar, objects up to 70 or so times the mass of Jupiter; too low mass to ignite fusion in their cores to become true stars. They found ~160 planetary mass objects and ~760 brown dwarf objects (I’ll note these are candidates; they need to be confirmed).

The dip between the two peaks occurs right around the mass of objects that can start fusion. Why? There are two ways to form objects from a gas cloud: Direct collapse from the gas itself, or clumping of material around the disk of a forming star.

Stars are thought to form from direct collapse; a knot of material in the gas can be big enough that gravity causes it to collapse, forming a star. Around that star you get a flattened disk of material, and planets form from that. They build from the bottom up, as grains clump together to form rocks, and these aggregate to form larger and larger objects.

If a star forms from the gas, it tends to blow away the gas around it. That’s why you expect a drop in the IMF at that mass; the birth of the stars themselves cuts it off. But that second peak means something else is going on. It’s not clear what, but one explanation is that brown dwarfs form along with stars, gathering mass from the disk around the young star. Then, after some time, they get ejected, perhaps due to the gravity of other nearby stars (especially if they form in multiple star systems, where such encounters would be more common).

This sort of thing is pretty new; it’s only been recently that we’ve even had the capability to make these observations down to such low masses. Astronomers have been looking into the IMF for decades, but with powerful tools like VLT and HAWK-1 they can now peer more deeply than ever before, and uncover these faint, low-mass objects (I’ll note the first brown dwarf wasn’t even found until 1995).

In astronomy, our growth in knowledge is directly tied to our prowess in creating more powerful technology to observe the heavens. And when we do the Universe rewards us with more understanding, and a deep appreciation for the laws of physics and Nature.

That’s a pretty good deal.

* Usually, exoplanets form with stars, but under some conditions they can also form on their own. These objects are what we call rogue exoplanets, wandering space with no host star to warm them. Most rogue exoplanets may have formed around stars and gotten ejected from their parent systems, but some formed that way in the first place. Understanding how many of each exist in the galaxy would help us understand the dynamics of how they’re formed in the first place.

Categories: Astronomy Headlines

A Chance to See Moons Around the Exoplanet Beta Pic b in 2017

Thu, 08/11/2016 - 06:00

I don’t usually write about observations that haven’t been done yet, but this is so interesting I wanted to tell y’all about it. Next year, due to a quirk of geometry, it’ll be possible for astronomers to search for moons or other debris around the exoplanet Beta Pictoris b. They won’t be able to see the planet itself, but if there’s stuff around, that might be detectable.

The star in question is Beta Pictoris, which is about 60 light years away (that’s relatively close). It’s more massive, hotter, and brighter than the Sun. It’s also considerably younger: It’s about 25 million years old, while our star is over 4.5 billion years in age.

In 1983 astronomers found that Beta Pic was putting out more infrared light than expected, and detailed observations revealed it was surrounded by a disk of warm dust and debris, the material left over from the formation of the star (I remember doing a homework problem in grad school about the excess IR light from the star, using it to calculate the mass of the disk). As it happens, we see this disk nearly edge-on.

Then things got even more exciting: In 2003, observations using the Very Large Telescope directly imaged an exoplanet orbiting Beta Pic!

Called Beta Pictoris b, it has about seven times the mass of Jupiter, and orbits the star roughly every 20 years. In fact, its motion around the star can be seen; observations made in 2009 and 2010 show it on the other side of the star from where it was in 2003!

Getting the exact orbit of the planet is difficult because it’s hard to get accurate enough observations to really pin it down. However, using new techniques, a team of astronomers looked at data from the massive Gemini telescope to get amazingly accurate positional data from the planet. What they found was good news and bad news.

The bad news is that the planet’s orbit is almost certainly not edge-on as seen from Earth (that would need a tilt of 90°, but the tilt they found is 88.8°; close but no cigar). That means the planet doesn’t actually transit its star, passing directly across the star’s face as seen from Earth. That would be nice, because that sort of observation can be used to get the planet’s size.

But not all is lost. The good news is that the planet gets very close to transiting the star, close enough that its Hill sphere will actually pass in front of it.

What’s a Hill sphere? Why, I’m glad I asked.

Gravity depends in part on how far you are from a massive object. As you move farther away, it weakens. If that object is a planet, and it orbits a star, at some distance from the planet the star’s gravity has more influence on an object in space than the planet’s gravity. If you’re closer to the planet the planet’s gravity dominates, and it can hold on to orbiting objects. That defines a spherical region around the planet, called the Hill sphere.

The size of the sphere depends on the mass of the planet, the mass of the star, and the distance between them. For example, the Earth’s Hill sphere reaches out to about 1.5 million kilometers. The Moon, orbiting 380,000 km away, is well inside that, so its motion is mostly influenced by the Earth (some people like to say the Moon orbits the Sun more than it does the Earth, but those people are wrong). Weirdly, Pluto’s Hill sphere is much larger than Earth’s, but that’s because it’s so far from the Sun that an object can orbit Pluto from farther away and still be heavily influenced by it.

The Hill sphere for Beta Pic b is over 160 million kilometers in radius, which is pretty large. That means it can hold on to moons or some of that leftover debris out to that distance. Although the planet itself won’t transit the star, it turns out that this region will, starting in April 2017 and ending in January 2018. The planet’s closest approach to the star will be in August, which is when the transit could allow astronomers to probe material closest to the planet.

I won’t mince words: This is really cool! The astronomers suggest a campaign to observe the star during these times, though they note that the first half of the Hill sphere transit won’t be easily visible to ground-based telescopes because it will be near the Sun in the sky (though space-based ‘scopes should be able to take a peek). But the second half of the transit should be visible to observatories in the southern hemisphere.

Hopefully constant monitoring will be done. There’s no guarantee anything will be seen, but if a large moon does happen to pass in front of the star, this would be the first such exomoon ever seen (assuming none is found between now and then orbiting some other exoplanet). That’s a very big deal indeed. Moons orbiting planets gives us a chance to determine the mass of the planet, for one thing.

And for another, we’ll be detecting a moon orbiting a planet that in turn is orbiting an alien star!

That is just simply cool. But it’s also premature. We’ll have to wait and see, and keep our astronomical eyes open. This is a chance that won’t come back until Beta Pic b circles its star once again… in just another 20 years or so.

Tip o’ the dew shield to Jason Wang on the Exoplanet Imaging Group on Facebook.

Categories: Astronomy Headlines

I Still Still Don’t Think It’s Aliens, But Tabby’s Star Keeps Getting Weirder

Wed, 08/10/2016 - 06:00

Just when you think Tabby’s Star can’t get any weirder, it goes and does.

You know this star: It undergoes very odd dips in brightness that have defied explanation. The star, formally called KIC 8462852 (but nicknamed Tabby’s Star after Tabetha Boyajian, the astronomer who led the team investigating it, has been observed by the Kepler spacecraft for some time now. Kepler looks for dips in brightness in stars indicating the presence of a planet orbiting it; the planet blocks a tiny bit of star light, and that drop in brightness can be detected.

But Tabby’s Star isn’t behaving itself. Instead of a smooth dip and subsequent rise in brightness indicating a planet, it suffers non-periodic, asymmetric, and very deep dips in brightness. This is not at all what you expect from a planet. Ideas including shattered asteroids and swarms of comets explain some but not all of the dips.

After a while people began to wonder: What if advanced aliens were building huge megastructures around the star, in order to capture its light to power their civilization? I know, that’s a bit far-fetched, but it actually fits the data pretty well. No scientist really thinks that’s the case —it’s a reach, and no signals from aliens have been found— but nothing else works, either. It’s baffling.

Then an announcement was made that over the past century or more the star has been fading at an unprecedented rate. This finding was immediately called into question, though, and the issue of fading remained unresolved.

But now a new study, using data from Kepler itself, shows that Tabby’s Star really is fading, and at quite a clip: Over three years of observation it faded by nearly one percent, then took a sudden nosedive, fading by two percent in the next 200 days.

I know, that doesn’t sound like much, but remember this is an entire star, a mighty source of energy. Stars like this one just don’t do that! What’s causing it?

The astronomers first looked at the data to make sure the fading was real, and after careful investigation concluded it is. It’s not some instrumental effect from Kepler itself, but instead is something happening on, at, or near the star.

They looked for other factors, like stars around it changing brightness, but don’t see anything amiss that might throw off the data. They looked at quite a few stars around Tabby’s, and only saw a handful that exhibit similar fading, but none with that sudden two percent drop.

Whatever that star is doing, it’s actually doing it.

So what could it be? It’s not a planet; it would have to be far larger (0.15 times the size of the star itself!) than any planet could be to make such a large dip, and the slow change would mean it was implausibly far from the star. A cloud of material might do the trick, slowly passing in front of the star and blocking its light, but that doesn’t explain the sharp dips, either.

The researchers find that a recent collision of asteroids or comets might account for almost everything seen; the big dips would be from clouds of material, and the smaller rapid dips from more solid bodies. But that doesn’t explain the century-long dip, or the fading seen by Kepler (I’ll note the recent fading is consistent broadly with the much longer fading, but doesn’t necessarily prove it’s real).

Nothing explains everything we see. It’s a mystery.

Clearly, more observations are needed. A cloud of dust could redden the star, in much the same way that atmospheric haze on Earth makes the setting Sun look redder, so a change in the star’s color would be interesting. The astronomers also suggest looking for planets farther out from the star, perhaps a few hundred million kilometers from it. The gravity from a planet like that could, in theory, gravitationally align a disk of material around the star (think of it as a thick, dusty asteroid belt) that could explain some of the features.

Could that be what’s doing all this? Maaaaaaybe. There are still a few ideas tossed around that can explain Tabby’s Star behavior, but all are maddeningly, tantalizingly difficult to ascertain.

Mind you, I’m still not saying aliens. I really and quite seriously don’t think that’s it. It’s more likely we’re seeing a combination of effects doing this; a cloud of material sliding in front of the star, dimming it slowly, with thicker clumps causing the sharper fading. But even that doesn’t explain all the data.

The only thing we know for sure is that we haven’t ever seen anything like this before, and that we are seeing is really, really weird.

And weird is good! Scientists love mysteries, especially the distinctly odd ones. This is tremendously fun science, with more questions than answers. But with more observations and more clever analyses, I hope that will reverse. Even if it’s not a technologically advanced civilization, I want to know what is going on!

Categories: Astronomy Headlines

NASA High Definition Camera Creates Stunning Slo-Mo Rocket Booster Footage

Tue, 08/09/2016 - 06:00

On June 28, NASA test-fired a solid rocket booster being built for its Space Launch System rocket. The test went well … but it wasn’t the only thing being tested.

A sophisticated new type of camera was also getting a shakedown run: It can record very bright and very faint objects all at the same time. The resulting slow-motion footage of the SLS booster test is mesmerizing:

The camera, called NASA’s High Dynamic Range Stereo X (or HiDyRS-X), uses a variation on high dynamic range processing. HDR pictures, when done in the standard way (like in many phone cameras), can show a broader range of brightness. Instead of taking a single picture, the camera takes several at different exposures, then uses software to analyze the images and creates a composite that takes the brightest parts of the scene and uses the shortest exposure for them, while using the longer exposures for fainter parts. When combined, everything looks exposed correctly.

This won’t work for video, at least not easily. Taking multiple exposures takes time, and if you’re trying to see something that moves quickly—like a rocket plume—that’s a problem! This is where the new camera is very clever: it uses onboard technology that exposes each individual pixel separately, so that bright and faint parts of the shot are balanced in each individual video frame.

The results are stunning. A normal video camera shows the rocket plume as being hugely overexposed compared with, say, the engine nozzle (see the image at the top of this article). But in the HiDyRS-X video you can easily see both, allowing for accurate tracing of plume dynamics, which is critical if you want to understand how the rocket engineering affects the thrust.

While I am no fan of the SLS (to say the least), I am still mightily impressed with this footage. A camera like this will be massively useful not just for NASA but in many other applications. In fact it was NASA that helped it get developed; it was created by engineer Howard Conyers under the auspices of the Big Idea Challenge, a design competition looking for innovative, game-changing ideas. It looks like they found a good one here.

Tip o’ the lens cap to Fark.

Categories: Astronomy Headlines

GOP Senator Ron Johnson: Lack of Global Warming Is “Scientifically Proven”. Yeah, About That…

Mon, 08/08/2016 - 06:00

Last week I wrote about a senior Republican Congressperson, Marsha Blackburn, who not only denies climate change is real, but made the bizarre statement that the Earth is actually cooling.

I know, right? But not to be outdone by his colleague in the other house, Senator Ron Johnson (R-Wisconsin) decided to let loose with a stream of nonsense on the same issue in an apparent attempt of what I can only think of as one-downmanship.

On the Glenn Klein radio show on Wisconsin’s WRJN on Aug. 2, 2016, Johnson decided to let the world know his grasp of science is at best tenuous, and he’s more than willing to grease his fingers. As an example, he said this:

First of all the climate hasn’t warmed in quite a few years, that is proven scientifically.

Oh, Senator. If you want to talk scientifically, then the global warming “pause” you’re referring to doesn’t exist. We’ve had nine record-breaking high temperatures globally in a row. 2015 was the hottest year on record, beating the previous record-breaking high temperature year of 2014. Every single year of the past 13 years has been among the hottest ever recorded.

“Proven scientifically,” the Senator says. Right.

But he’s not done letting loose the zombies of denial. He continues:

So, that’s why they changed the terminology from “global warming” to “climate change”. That covers everything. Climate has always changed, it always will.

This is one of the most egregious of the denier lies, and one of the most aggravating: Changing the framing from “global warming” to “climate change” was a Republican strategy. It wasn’t progressives who did that, it was Frank Luntz, a Republican strategist, who did it to make it sound less “frightening”, the easier to downplay it.

Sheesh.

Then he makes a more subtle but still grossly incorrect statement:

… [Measured from ice cores, over hundreds of thousands of years] we’ve had temperature variations of 22.7 degrees. There were men and women 20,000 years ago, but not enough building campfire to produce CO 2 to cause those glaciers to recede or to cause those temperature variations… There are greater forces at play.

I’ll admit he does say one correct thing there; surface temperatures measured in Antarctica from the Vostok ice core show a variation of roughly 22° F over time. But note that phrase: “over time”. Natural variations in climate do occur, and no scientist will deny that. As I wrote in the post about Blackburn, the problem is that as humans dump carbon dioxide into the air at huge rates, the speed at which the temperature is now changing is unprecedented. Slow variations are bad enough, stressing the environment and forcing species to adapt; but if it happens too quickly it’s not possible to adapt quickly enough. Rapid climate change can force huge numbers of species to go extinct, and the effect it will have on humanity is profound and terrible.

There’s one other thing Johnson says worth pointing out (though there’s plenty more wrongness to be had in that interview):

… the question is, how much does man cause changes in our environment, changes in our climate, and what we could possibly even do about it?

Actually, that question had been asked and answered. Essentially all the global warming we’re currently seeing now is caused by human activity (without it, the Earth actually would be cooling slightly). Scientists who study climate overwhelmingly agree about that.

And there is something we can do about it:

Vote science deniers out of office.

And hey, isn’t Senator Johnson up for re-election this November?

Categories: Astronomy Headlines

Pages