Bad Astronomy Blog

Another Mind-Crushing Illusion: Straight or Curved Motion?

1 hour 56 min ago

From the twisted mind of brusspup comes another brain-hurting illusion. This one is really, really convincing, so tell me: When you look at this video, you’re seeing a circle of eight dots rotating as it spins around inside a bigger circle, right?

No, you’re not. As brusspup shows, each individual white dot is moving in a straight line! The trick here is two-fold: One is that the dots aren’t moving at constant velocity (you can see that in the video at the 0:44 mark), and that combined their motion mimics what we’d see if a smaller circle is rolling around inside a big one.

Try as I may, when I look at this video I can’t make my brain see the dots moving linearly; it looks like a circle rolling. If I focus on one of the dots I can see it moving back and forth along a line, but the others still look like the rim of a circle rolling around. For most illusions there’s a moment when your brain can see what’s going on and the illusion shatters, but not with this one. It’s maddening.

When I was a kid, Spirograph was a very popular “game.” It wasn’t really a game, but a set of clear plastic disks with gear teeth around them (or rings with teeth on the inside). They had holes in them; you’d pin a ring down on a piece of paper, then take another disk, place it inside the ring, put your pencil tip in a hole, and roll the inner disk around inside the outer ring. The results were really lovely and graceful interlocking and overlapping curves. If you’re a lot younger than me and missed this craze, here’s a video that’ll help you picture it:

Man, I miss Spirograph. It was so much fun*! And this dots illusion is related. In Spirograph, when you’d use your pencil to roll around the inner disk, the motion you made was very similar to what you’re seeing in the illusion; it was more of a back-and-forth motion than an around-and-around one. It’s difficult to explain without math, which I find funny; I have a visceral feeling for it because of all those hours I spent playing with a Spirograph when I was little.

If you want the math, then here you go: The shapes made this way (tracing the motion of a point on a circle as it rolls) are called cycloids, and there are a lot of varieties: epicycloids, hypocycloids, and others, depending on how the inner circle is rolled. I once modeled the shell of gas around a supernova as an epicycloidic shell (like a peanut shell), and it reproduced what we saw with Hubble pretty well (even though it formed in a very different way than a cosmic Spirograph!).

I’ll note that when a circle rolls along a straight line, if you watch a single point on it you can break the motion up into two dimensions: Horizontal and vertical motion. These motions aren’t constant, but depend on the sine and cosine of the time elapsed. They start off motionless, accelerate to a maximum speed in the middle, then slow back down to zero … and in each direction, the point moves linearly! It’s only when you combine them that you get the cycloid.

That’s how this illusion works. By mimicking this trigonometric motion, your eyes and brain are fooled into thinking the dots are acting together, portraying the rim of a circle. But they aren’t; their motions are related but independent of one another (what’s called “parametric” in mathematics).

A-flippin’-mazing. But also MATH! And SCIENCE!

And another in a long, long series of illusions that shows very well that seeing is not necessarily believing. Our brains are very easily fooled, and that’s very important to remember in life.

[Tip o' the Necker cube to a lot of folks, including Oren Geva, Mitchell Moffit, and Gizmodo.]

Related Posts: More illusions by brusspup and others

Another Brain-Melting Illusion: The Dragon That Follows Your Gaze
An Optical Illusion You'll Swear Is Moving. It Isn't.
The Magic of Physics: A Water Spiral
Viral Illusion Will—and Should—Have You Doubting Your Eyes
The Blue and the Green (the single greatest illusion OF ALL TIME).

* Holy cow! Even in today’s app-based world, a good old manual analog Spirograph set is still available to buy! I may buy a bunch just to give to friends who have kids. Or even if they don’t.

Categories: Astronomy Headlines

Plunging Deep into Colliding Galaxies

5 hours 1 min ago

Roughly 50 million light years from Earth is the most spectacular example of galactic collision in the sky: the famed Antenna Galaxies, two huge spiral galaxies in the middle of a cosmic train wreck. Playing out over hundreds of millions of years, the gravity of the two galaxies has distorted their shapes, flung out streamers of stars a million light years long, and triggered a burst of star formation so intense that billions of new stars are being born in the galaxy’s hearts.

As mighty as this event is, 50 million light years is a long, long way. The details of this collision used to be discernible only using giant observatories like the Very Large Telescope or Hubble.

But not anymore! Behold Rolf Wahl Olsen’s newly-released picture of the Antennae and prepare to scrape your jaw off the floor (you'll want to make your browser wider for this):

That magnificent shot was taken with — get this — a 32 cm (12.5”) telescope Olsen built himself. It took him 38 nights of observing from January to June of 2014 to get to a total of an amazing 75 hours of observing time for this gorgeous image. He says the faintest stars visible are around 24th – 25th magnitude; the faintest star you can see with your naked eye is 25 million times brighter than that.

So yeah, this picture is deep.

The detail really is stunning. Olsen compared his image to those taken with Hubble and the VLT, and while of course his resolution isn’t as good (there’s no way a small telescope can discern details as well as much larger telescopes) it’s amazing what features you can identify in his shot compared with the professional observatories.

What you’re seeing in this image are two massive galaxies undergoing a physical collision. Over the lifetime of the Universe, galaxies collide fairly often; our own Milky Way has collided with and consumed quite a few smaller galaxies to grow to its current size. But collisions between two large galaxies is more rare, and we’re fortunate to have such a fantastic example like the Antennae so close to us.

The collision started more than 600 million years ago. As they approached each other, their mutual gravitational attraction drew out long streamers of stars (called tidal tails) from the other. The galaxies aren’t colliding perfectly head-on, but instead first missed each other by a bit. Their gravity swung the two galaxies around, giving them a bit of rotation; that’s why the tidal tails form long, graceful arcs.

After they swung around, the galaxies headed for each other again, colliding for a second time and starting the long, long process of merging into a single, larger galaxy. Amazingly, it’s unlikely there will be a single collision between two stars; stars are very small compared to the space between them. But gas clouds are huge, light years across, and collisions between them are common in these events. When clouds slam into each other they collapse and form stars. These collisions can spur huge amounts of such activity, creating what we poetically call a starburst. In Olsen’s image, the clouds are pink and red due to glowing hydrogen gas, excited by the vast numbers of massive stars forming within them.

Star birth also creates huge amounts of dust — long, complex molecules based on carbon — which is opaque, so the dust clouds block the light from stars behind them. You can see the ribbons and filigrees of dust in Olsen’s image, and of course even better in the VLT and Hubble pictures.

If you still need one more thing to send chills down your back, then think on this: In four billion years the Milky Way will collide with the massive Andromeda Galaxy, and if there are any spectators a few dozen million light years away, what they will see all those eons hence will look very much like what Olsen has shown us here.

It’s simply mind-blowing to see what can be done with so-called “amateur” equipment these days. What was once the sole purview of professional observatories (before the invention of the digital camera) can now be reproduced with far less, if someone is willing to be so devoted to it. I’m glad Olsen is.

And if you need more of his work, then you should see his images of the active galaxy Centaurus A, his glimpse of a forming alien solar system, and what he did with Voyager images of Neptune. It takes him a long time to put together each of these shots, and so we don’t hear as much from him as other folks putting their eyepieces to the sky. But if he continues to create such astonishing works like these, I can be patient. It’s worth it.

Categories: Astronomy Headlines

Go Forth and Science

Mon, 07/21/2014 - 08:03

Thank you.

In April 2014, Slate announced its new paid membership program called Slate Plus. The Hive Overmind at Slate asked us writers to promote it and even had a contest: Whoever got the most people to sign up would get a $500 bonus.

Seeing that I have a pretty big audience here and that I was asking that audience to pay for something, it didn’t feel right to keep that money if I won. So I announced that if I did win I’d give it all to Donors Choose, a non-profit group that organizes donations to classroom teachers around the U.S. (think of it as a Kickstarter for learning).

Well, guess what? A lot of you folks signed up for Slate Plus. Enough so that I won the contest.


So I just had a delightful time going through the various science teachers’ pages at Donors Choose, looking for projects that needed funding. I found quite a lot, so I narrowed my criteria: Projects that were near full funding but just shy of the goal, coupled with good science, coupled with classrooms that needed the money, coupled with teachers who seemed to have that special quality, that spark, that got me so excited about science when I was a kid.

I found four that (literally) fit the bill: Learning in Motion (Mr. Estrada), Bringing Space to Our Room! (Mrs. Gibson), Mad Scientists Explore (Ms. Sunnucks), and Bring Vital Learning Technology to My Classroom (Ms. Carr). All four of these projects are now fully funded, and these educators can go forth and teach their kids science.

To all of you who helped out, thank you. You got more than just a subscription to Slate Plus; you helped hundreds of children across the country get a chance to explore the Universe around them.

You should feel really good about that. I know I do.

And if you like, there are plenty more worthy projects still needing funding at Donors Choose. Go.

Categories: Astronomy Headlines

Robert F. Kennedy Jr.: Still Fighting the Wrong Fight

Mon, 07/21/2014 - 04:30

Let’s get this out of the way right at the start: I’m not a big fan of Robert F. Kennedy, Jr. This is almost entirely due to his grossly erroneous belief that a preservative in some flu vaccines causes autism. This preservative, thimerosal, has been tested thoroughly by many different groups, and has never been found to have any connection with autism.

Got it? Vaccines don’t cause autism. It’s really that simple.

Despite this, RFK Jr. continues to beat this drum. In a recent Washington Post article, journalist Keith Kloor wrote about RFK Jr.’s attempts to talk to two Senators about his crusade against thimerosal, and about a new book he’s published about this topic. In the past, Kloor has been pretty matter-of-fact about RFK Jr.’s bizarre claims, so I expected this would be a pretty tough profile.

It wasn’t. Now, I don’t mean that Kloor treats RFK Jr. with kid gloves; the article actually shows his claims to be dead wrong, and portrays him as an outcast from the mainstream. That’s all fine. I just don’t think Kloor really showed RFK Jr.’s true nature; something we here at Slate have seen for ourselves.

In 2013 I wrote an article giving great details on just how over-the-top anti-vax RFK Jr. is, including his giving a talk at a rabidly anti-vax conference. After it posted, Slate got a call from RFK Jr. himself, requesting a chance to rebut over the phone. I declined; having read his writings and listened to his radio shows, I knew better than to let him rail away at me.

I was right. My editor, Laura Helmuth, decided to accept the call, and was subjected to RFK Jr.’s, um, opinions, for nearly an hour. She wrote an excellent article about it, describing his conspiracy theories and how he misrepresented what scientists told him. It’s an eye-opener.

And now, with this WaPo profile, Helmuth decided it was time to reiterate this point, so she has written another take-down of RFK Jr. I highly recommend reading it; it starts with this:

Most paranoid, grandiose, relentless conspiracy theorists can’t call a meeting with a U.S. senator. Then there’s Robert F. Kennedy Jr. 

… and it keeps going from there.

RFK Jr. has a lot of clout, quite a bit of which comes from his family name. But to me he is in the same heap as people like Jenny McCarthy — those who make baseless, unwarranted claims about vaccines, sowing doubt and fear about one of the greatest medical triumphs in human history. In fact, the similarity between the two is striking, since RFK Jr. claims — despite his own actions — that he is not “anti-vax”, a claim McCarthy recently made as well.

As the entire US sees a huge spike in measles outbreaks, largely caused by unvaccinated people, and we’re also seeing a resurgence of other preventable diseases like whooping cough and polio (polio, for Pete’s sake!), making these outrageous claims about vaccines as RFK Jr. and McCarthy do is more than just irresponsible. It’s dangerous*.

I’ve been vaccinated my whole life, and I make sure to get my boosters as needed, too. I walk the talk. Don’t listen to people just because they have famous names. Talk to a board-certified doctor and get the facts.

* To be fair, RFK Jr.’s claims relate to vaccines that contain thimerosal, which are a tiny minority. But to be completely fair, a) he’s still wrong, and b) it’s all grist for the mill for the overall anti-vax movement. Wrong is wrong, and RFK Jr.’s claims are wrong.

Categories: Astronomy Headlines

From the Earth to the Moon to the Earth

Sun, 07/20/2014 - 04:00

45 years ago today — and for the first time in human history — human beings set foot upon another world.

It was one of the proudest moments in America’s history, arguably the proudest. Despite being initially motivated by small-minded territoriality, it ironically brought our planet together, with people all over the world watching breathlessly as Neil Armstrong placed his boot on the desolate surface of the Moon.

Every year on this anniversary I reflect a bit on what happened then, how it affected me, and what it means today.

Some people fret over whether it was all worth it, taking this one small step. I have no such doubts; we are better as a species for having ventured into space. The evidence for this is overwhelming, from learning about our planet (and the dangers to it), to the very nature of humanity’s need to explore that is so fundamental to our psychology.

Venturing into space is not just something we can do. It’s something we must do.

And yet here we are. It’s been 45 years since we put men on the Moon and 42 years since the last men left it. We’ve not gone back since, at least, not with humans. Sure, we’ve made a lot of progress about living and working in space: We’ve launched several space stations, put over 500 people into space, and built countless satellites and space probes. I’m fully aware of the awe-inspiring achievements we’ve made, and how much they mean.

But still, there is a hole in that picture. All of those people we’ve launched into orbit haven’t gone more than a few hundred kilometers above the Earth’s surface. The yawning chasm between the Earth and Moon hasn’t seen a human in it for over four decades.

As I’ve written before:

Now, there's a lot to be said for low Earth orbit. It is a fantastic resource for science, and I strongly think we should be exploiting it even more. But it's not the goal.  It's like walking halfway up a staircase, standing on your tiptoes, and admiring the view of the top landing.

When I look back over the time that’s elapsed since 1969, I wonder what we’re doing. I remember the dreams of NASA, and they were too the dreams of a nation: Huge space stations, mighty rockets plying the solar system, bases and colonies on the Moon, Mars, and asteroids. Those weren’t just the fantasies of science fiction. We could’ve done them. Right now, today, those dreams could have been reality.                                                                 

Instead, we let those small-minded human traits flourish. We’ve let politics, greed, bureaucracy, and short-sightedness rule our actions, and we’ve let them trap us here on the surface of our planet.

It needn’t have been this way, and it still needn’t be this way. There are those who still dream, who understand the call to space, and who are devoting their lives to make it reality. We’ve faced adversity before, and have not let it stop us.

I think we can overcome our own petty blindness. Sometimes we humans look up, not down, and see not just the Universe stretching out before us, but also our place in it.

We’ve done it before and we can — we must, and we will — do it again.

Per somnia et ardua ad astra.

Categories: Astronomy Headlines

Cruisin' Over the Caribbean

Sat, 07/19/2014 - 04:30

I just got back from travel, and now I'm deep into planning my panels for San Diego Comic Con next week, so at the moment I'm enjoying a slow, broiling panic.

But I couldn't pass up the chance to post this breath-taking picture of the Caribbean taken by an astronaut on the International Space Station as it sailed over on July 15, 2014:

Yegads. You very much want to embiggen that.

The bright lights to the upper left outline Florida (the long glow is from Miami), and you can trace cities up the east coast of the US. Cuba dominates the lower left (cut off a bit by an ISS solar panel), but the teal and turquoise waters of the Caribbean are what draw the eye. The islands right in the middle are the Bahamas, and the bright glow to their right, smack dab in the middle of the picture, is (I believe) Nassau — remind me not to go stargazing there! The lights must wash out the sky. But that's probably not why people go to Nassau in the first place.

Speaking of the sky, note the green arc of light over the Earth's limb. This is called airglow, and it due to the slow release of energy from sunlight the upper atmosphere stores during the day. It's actually a fascinating physical process which I've described before. In that link I also talk about the brownish-yellow glow beneath it: That's from glowing sodium in the air, and the source of that sodium may be meteors that have previously burned up in our atmosphere!

Amazing. There's no such thing as just a pretty picture taken from space — there is always a lot more going on than you might think. And just like any artwork, knowing the story behind the beauty makes it that much more wonderful.

Categories: Astronomy Headlines

Cosmic Duckie, You're the One...

Fri, 07/18/2014 - 02:30

[With apologies to Ernie.]

Right now, in deep space 400 million kilometers from Earth, the European Space Agency probe Rosetta is easing its way toward the comet called 67P/Churyumov-Gerasimenko (which, for obvious reasons, I’ll just call ChuGer). On July 14 it was a mere 12,000 km (7400 miles) from the comet — less than the diameter of the Earth! It took a series of images of the frozen iceball, and it’s becoming very clear that this comet is really, really weird:

It’s not an iceball… it’s an ice rubber duckie! And a big one, about four kilometers across.

As you can see, it appears to have two distinct components; a large, flattish piece and a smaller, rounder one attached off-center. You can see this a lot more clearly in an animation composed of 36 images taken about 20 minutes apart:

What the what? Note that the comet is only a couple of dozen pixels across as seen by Rosetta; the images in the animation (and on the right in the still image above) have been smoothed to give you an idea of what it looks like. Don’t take small details too literally, but the overall shape is apparently real.

It’s not clear why it has this shape, but there are several possible explanations of how it may have been molded this way.

Comets are big lumps of frozen water with dust and rocks mixed in. In fact, we sometimes call them “dirty snowballs”. It’s possible that two comets suffered a very low speed collision and stuck together, forming the weird shape.

However, that strikes me as very unlikely. Why? Space is big. That’s why we call it “space”. The odds of two comets coming that close together at just the right speed and angle to do this seem very low to me.

It’s more likely, in my mind, that ChuGer got whacked by a much smaller object, say a chunk of asteroid. Some comets aren’t solid, like rocks, but more like loosely bound rubble piles held together by the ice. Over the eons, small impacts would shatter it, creating deep cracks inside the comet. A slightly bigger collision could actually dislodge large chunks. If the impact speed were right, the big chunks might separate a bit and then slowly re-accrete over time due to their feeble gravity. What you’d get is a weirdly-shaped object, like if you took a small snowball and stuck it on the side of a bigger one.

Which is just what we see with ChuGer. I’m totally guessing here, but I have a sneaky suspicion that’s what we’re seeing.

Another way it could have gotten this shape is that it used to be rounder and smoother, but over time eroded away. Comets have lots of ice, and as they approach the Sun that ice turns directly into a gas (which is called sublimation) and streams away. Anything less volatile (like rocks inside) will remain. If the comet has big lumps of rock inside it, or just big pockets of ice distributed through it, it could erode asymmetrically, leaving huge lumps like ChuGer’s.

Again, I’m guessing. We’ve only visited a handful of comets spacecraft, and to be honest they’re all weird. Halley is a lumpy potato. Hartley 2 looks like a bowling pin or a dumbbell, with lobes made of carbon dioxide and a waist of frozen water. Other comets have been found to be similarly lobed, lumpy, and basically asymmetric.

The whole point here is that we’re exploring — we don’t know what we’ll find. If we did, it wouldn’t be exploring.

And we’ll find more, much more. Rosetta is still approaching ChuGer, and in early August will be a mere 100 km (60 miles) from the comet. It will enter orbit, examining the nucleus (the solid part of the comet) in excruciating detail. Then, in November, it will send out a lander named Philae to physically touch down on the comet’s surface! It will examine the comet and send the data back to Earth via Rosetta. Its planned mission will last about a week, and should be a huge bounty for astronomers and planetary scientists.

Over the next weeks I’ll be writing more about this amazing mission and the strange comet it’s studying. ESA doesn’t have the same policy of freely releasing images that NASA does, but hopefully when something new and spectacular is available, you’ll be able to read all about it here.

In the meantime, you can take a look at some of the amazing highlights from the Rosetta mission so far, including some jaw-dropping images of Earth, Mars, an asteroid named Lutetia (with a fantastic gallery), another lumpy diamond-shaped asteroid named Steins, and a lovely shot of the Moon rising over the limb of the Earth. These images show the promise of what we’ll see very, very soon once Rosetta is in orbit around 67P/Churyumov-Gerasimenko.

Categories: Astronomy Headlines

The Chaotic Glory of Starbirth

Thu, 07/17/2014 - 04:30

Robert Gendler is the gift who keeps on giving. He’s an accomplished astrophotographer (why, I would never make such a claim without ample evidence) who takes observations from professional observatories and adds to them images he’s taken himself and with other people. The result is substantial beauty… and here’s another bit of proof for you in the form of the ridiculously chaotic star-forming nebula NGC 1333:

This cloud is a sprawling stellar nursery, a dense cloud that’s still collapsing, fragmenting, and creating stars hither and yon. One feature of many young stars is that they rotate rapidly, and are still surrounded by the thick disk of gas and dust from which they formed. Their still-intense magnetic fields get wound up like a corkscrew, and this can launch twin beams of matter out from the poles of the star.

These are called Herbig-Haro stars, and NGC 1333 is littered with them. I found several perusing Gendler’s image, and inset one here. The cloud is choked with thick, opaque dust which hides a lot of the details. Infrared light can pierce that veil, though, so images from observatories like the Spitzer Space Telescope can reveal far more details. In fact, in that linked article I have an in-depth discussion both of this nebula and the HH objects in it (and a close-up of one that actually has curved beams, which are lovely). I suggest giving it a read to truly grasp the awe-inspiring nature of this object.

Gendler’s image is comprised of observations from the 8.2 meter Subaru telescope, the Digitized Sky Survey, telescopes with the NOAO, and his own data in collaboration with Roberto Colombari. These are magnificent telescopes, one of the reasons the final image is so spectacular. Another is that NGC 1333 is only about 1000 light years away, relatively nearby on a galactic scale (the Milky Way is 100,000 light years across). This makes it one of the closer massive star-forming regions in the galaxy, so we get a little more detail than we otherwise might.

It always amazes me that so much science can be found in objects so beautiful. I wonder what this tells us about our minds, our perceptions, and how we evolved to appreciate beauty... and how useful an ability like that can be?

Categories: Astronomy Headlines

Jovian Armageddon +20

Wed, 07/16/2014 - 04:30

Twenty years ago on this day—July 16, 1994—Jupiter got slammed, hard, by a comet.

It was the first time we had ever witnessed such a collision on a planetary body other than the Earth. I’ll note I’m very glad it wasn’t Earth; we wouldn’t be here talking about it if the comet had had us in its crosshairs instead of Jupiter.

The comet was discovered on March 24, 1993, by the team of Eugene and Carolyn Shoemaker and David Levy, who were taking pictures of the sky to look for comets. Right away they knew they had something odd—although comets are generally fuzzy and elongated, that’s usually due to their long, sweeping tails. This one appeared to have a long, fuzzy head. The head is the central part of the comet, the solid nucleus (generally made of ice and rock) surrounded by gas. Heads are usually pretty compact, but this comet had one that was stretched way out, like a thick line (I have a fun post describing all the parts of a comet and how they work).

Being the ninth comet the team had found, it was dubbed Shoemaker-Levy 9, or, more technically, D/1993 F2. Those in the know just called it SL9.

It was noticed that the comet was near Jupiter in the sky. The team backtracked the orbit in time, and found it had recently passed very close to Jupiter … and in fact, it was in orbit around the planet! At this point, a more complete picture emerged.

The comet had orbited the Sun for billions of years. But in the 1960s or 1970s it made a close pass at Jupiter, and the giant planet captured it. This is a relatively rare scenario and takes a fairly specific set of circumstances to occur. However given enough time and billions of comets, it’s inevitable.

The comet orbited Jupiter on a highly elongated path. On July 7, 1992, it passed so close to Jupiter that the planet’s mighty tides tore the comet apart. The pieces separated along a line, and when it was discovered a year or so later these distributed pieces are what gave the comet its squashed look.

And then astronomers got the big surprise: Calculating the orbit of the comet into the future, they saw it would physically collide with the planet in July of 1994!

I was in graduate school at the time, and boy, howdy, do I remember the excitement. No comet or asteroid had ever been seen hitting a planet besides Earth before. And SL9 was made up of dozens of individual pieces, each on a doomsday path to Jupiter! This was going to be big.

Unfortunately, the pieces were due to hit on the far side of Jupiter, which means we wouldn’t directly see the impacts. But it turns out we still got quite a show.

When the day came, practically every telescope on and above the Earth was watching. The first piece impacted at 20:13 UTC (2:13 p.m. ET) on July 16 … and within minutes pictures started pouring in from telescopes. Although the impact was on the other side of Jupiter, the huge plume from the impact rose so high it could be seen over the limb of the planet. Within a few minutes the impact site rotated into view, and we were all stunned to see photos showing a vast scar from the collision. The first piece (Fragment A) was about 2 kilometers in diameter and moving at 60 kilometers per second when it hit Jupiter—the energy equivalent of over a million one-megaton nuclear bombs exploding at the same time.

So yeah. We saw the impact scar. Here’s an infrared animation of the Fragment A impact made from observations using the 3.5 meter telescope on Calar Alto in Spain:

The bright spot to the upper right is Jupiter’s moon Io, and you can see the Red Spot, too. Then the impact blossoms as Jupiter’s rotation swung it into view. Yikes.

Within minutes, Hubble Space Telescope images were sent down, revealing the impact site: a vast splotch with a crescent-shaped fan of material blown ahead in the direction of the comet’s motion. Fragment A’s collision left a scar on the top of Jupiter’s clouds larger than Earth itself. It was stunning.

Over the course of the next week the remaining pieces hit, one after another. Fragment G was the biggest, but several were over a kilometer across. Jupiter’s powerful gravity accelerated them to their doom, and each gave up their individual ghost with a titanic explosion.

In the end, this was one of the most studied events in the history of astronomy. And it was full of surprises. We expected to see a lot of water released by the impacts, since it was thought there was a layer of water vapor in Jupiter’s atmosphere. Some was seen, but not nearly as much as predicted. The impacts generated tremendous waves in the atmosphere of Jupiter that were seen traveling away from the collision for hours. The chemical composition of the atmosphere was temporarily altered as well.

A few things remain stuck in my memory from those days. One was how dang slow the Internet was; we’d wait forever to download a 100kb image of the impact from the SL9 sites where they were being uploaded. It didn’t help that a million other people were trying at the same time. Back then, the ‘Net was pretty new, and most servers couldn’t handle so many people trying to access them.

Another fun memory was a live press conference the Shoemaker-Levy team was giving. They were discussing the comet on air when my friend and planetary scientist Heidi Hammel ran in (live on TV, remember) with printouts of the Hubble observations showing the impact event. All three of the team members’ faces lit up, the fruition of their work in front of them. Not long after, news shows ran a clip of several joyous astronomers cheering as they stood around a computer monitor watching the images come in (one of them was another friend, Melissa McGrath, with whom I went to grad school, and I always got a kick out of seeing her jumping up and down with excitement). All of this was shown on a National Geographic show, and a clip is on YouTube:

The other vivid memory was from a few days later. I was at the University of Virginia, and we had a huge 24-inch telescope there, built in 1885. I went out to observe Jupiter, but the air was unsteady that night, and all I saw was a blur.

So I went around the observatory to “The Doghouse,” a smaller brick enclosure that housed a vintage 6-inch brass ‘scope. Pointing it at Jupiter, I was stunned to my core to clearly see several black scars punctuating the planet’s cloud tops. The bigger telescope accentuated the blurry air, but the smaller one didn’t have as much magnification, and the unsteady atmosphere of Earth didn’t affect the viewing as much. I remember standing there, slack-jawed, knowing I was witnessing history.

Since those days two decades ago we’ve seen Jupiter hit several times; in July 2009, in June and again in August 2010, and a fourth time in September 2012. We’ve seen Saturn’s rings get hit by debris (actually multiple times), the Moon hit by small asteroids, asteroids themselves collide, and we just missed seeing an asteroid impact on Mars … but a comet will pass so close to Mars later this year that it could rain debris down on the planet. We’ll see.

And, of course, our very own Earth got whacked by the Chelyabinsk asteroid.

The lessons of SL9 are many. Impacts still happen across the whole solar system, even after 4.56 billion years. We need to keep watching the planets and look for such rare events. And, of course, the Earth is no exception as a target.

But looking back to those days, what I really remember is the excitement, the wonder, the anticipation, and how the public was just as fired up as we were. Every time I deal with some anti-science nonsense, some attack on what we know to be true, I remember this:

This stuff is real. And the public, when it comes right down to it, loves it as well. On this anniversary of one of the biggest bangs in the solar system, I think we all need to be reminded of that.

Categories: Astronomy Headlines

How Did the Bald Eagle Nebula Hatch?

Tue, 07/15/2014 - 04:30

You’d think that by now — with dozens of telescopes on, above, and below the ground, observing the skies from all latitudes and longitudes, and having centuries of time in which to work — every object in the sky would be cataloged and understood.

But that’s not the case. Not at all. There are still plenty of weird beasties to tease out of the dark, astronomical oddities hiding in plain sight. One of them is G 70.5+1.9, which is way prettier than its catalog-generated name might suggest. Here’s the proof:

That gorgeous photo is by my pal Travis Rector, who noticed it at the edge of another nebula he was observing. Travis notes it looks like a Bald Eagle in flight, the bright head to the left, the bluish strands outlining the beak. I have to agree. You can even see a wing above it, the tail behind, the taloned feet below! The prosaic name notwithstanding, I think The Bald Eagle Nebula is a far better moniker for it.

Right away I figured it for an old supernova remnant. When a star explodes, a lot of gas is expelled into space at a ferocious clip. It slams into the gas surrounding it, creating huge and powerful shock waves. This compresses the gas and makes it glow. As the remnant ages it can look like a loose circle of filaments that interweave like a wicker wreath (some very massive stars can create similar structures on a smaller scale). The Veil Nebula is an excellent example of this, as is the Pencil Nebula.

But there’s a monkey in the wrench here. Most old supernovae remnants give off radio waves and X-rays, the result of the shock waves moving through the gas. The Bald Eagle Nebula shows no real signs of either. That’s weird. It’s not totally unprecedented — a handful of other SNRs are also radio and X-ray quiet — but it’s unusual.

One reassuring measurement does fit the bill, though. Different elements in the gas emit different colors of light, allowing us to measure the relative abundances of the elements in the gas — for example, Travis’ picture was taken using filters that isolate light from hydrogen (red) and oxygen (blue). Different types of objects (like gas blown out by young stars, or gas forming new stars) tend to have different element ratios in them, and emit light differently. Astronomers who observed this nebula noted that the light emitted is far more consistent with an exploded star than anything else.

So it does look like this is the last raging scream of a star that died long ago, sending its innards into outer space. As these things go it’s relatively close, likely less than 3500 light years away. That’s still too far away to have directly affected us here on Earth, but I wonder if anyone, long ago, noticed a bright “new” star appearing in the constellation of Cygnus one summer, and gawked at it over the nights as it outshone Venus, then faded away over the ensuing weeks.

It must have been a total mystery to them… but then, it’s still somewhat of a mystery to us, too. That’s actually pretty cool. If we solve all the mysteries of the Universe, what fun will there be left for us to discover?

[Travis is an accomplished professional astronomer as well as an artist when it comes to imaging; you could do a whole lot worse than spending some time perusing his magnificent gallery of astronomical beauties.]

Categories: Astronomy Headlines

What’s the Quicker Solar Weight Loss Plan: Solar Wind, or Nuclear Fusion?

Mon, 07/14/2014 - 04:30

I know this may seem obvious, but… the Sun is big.

Really, really big. It’s over 100 times wider than the Earth, and over a million Earth would fit inside it. If you could weigh them on a cosmic scale, you’d find the Sun is over 300,000 times the mass of the Earth!

But that last number is dropping. Slowly, over time, the Sun is losing mass. It’s actually doing this in two ways: directly, via its solar wind, and indirectly, by converting mass into energy and shining brightly.

This raises an obvious question: Which one is faster? Which method is better at making the Sun shed those kilograms?

The Solar Wind Diet

The solar wind is just that: a vast stream of subatomic particles blowing away from the Sun. It’s composed of various types of particles, including electrons, protons, and even things like helium nuclei. Shaped by the Sun’s powerful and complex magnetic field, these particles are flung into space at high speed, ranging from a few hundred kilometers per second to many thousands.

The Sun blows off just as many electrons as protons, but protons are so much more massive we can ignore the electrons (and helium is only about 4% of the total, so we can ignore it too). Using satellites we can directly measure how many protons fly past the Earth in the solar wind. If you had a little net in space one centimeter on a side, you’d catch about 300 million protons every second at the Earth’s distance from the Sun.

But that means you’d miss a lot. The Sun is sending them out in all directions (though, to be fair, more along the Sun’s equator than at the poles, which we’ll ignore), and your little net is smaller than a postage stamp. To catch all the protons, you’d need to make a shell around the Sun at the Earth’s orbit. That shell would have an area of a staggering 3 x 1027 square centimeters — that’s three octillion little nets!

If one net catches 3 x 108 protons every second, then our big shell would catch 9 x 1035 of them. Each proton has a mass of 1.7 x 10-24 grams, so every second that means the Sun blows off about 1.5 trillion grams, or 1.5 million tons of material!

OK, so that’s Diet Plan 1, which loses the Sun 1.5 million tons per second. So what about Diet Plan2?

The Nuclear Fusion Diet

The Sun gives off energy, and that energy has to come from somewhere. Deep in its core, the Sun is busily converting mass into energy. That energy works its way out of the Sun and flies away into space in the form of light.

We know how bright the Sun is, that is, how much light it gives off. And we know — thanks to Einstein — how much mass it takes to create energy. So let’s see…

Doing the same sort of math as above, except measuring the light we see from the Sun per square centimeter as measured from the Earth, we find that the total energy emitted by the Sun is 4 x 1033 ergs per second (an erg is a teeny unit of energy).

But we also know that energy = mass x the speed of light squared. Rearranging to solve for the mass, and using the usual constant c for the speed of light (3 x 1010 cm/sec), we get

Mass = energy / c2  

Plugging and chugging: mass = 4 x 1033 / 9 x 1020 = 4.4 x 1012 grams per second, or over 4 million tons per second.

So there you go. The Sun loses 4 million tons of mass per second due to fusion. Fusion wins over solar wind as a stellar diet plan, by about a factor of two or three.

To be honest, I find it surprising the numbers are that close. Without any prior knowledge, it seems like either one could be thousands or even millions of times the other. Yet they’re about the same.

Run Away!

An interesting thought: The Earth orbits the Sun, held sway by its gravity. But as the mass of the Sun goes down, the Earth is held a bit less strongly. What happens then?

I’ll spare you the math, but it has to do with angular momentum and it being a constant. What happens in the end is that the Earth’s orbital radius increases as the Sun loses mass, and it does so linearly with the mass loss. In other words, if the Sun loses 1% of its mass, the Earth’s orbit increases in size by 1%.

The Sun is losing about 6 x 1012 grams per second, and has a mass of 2 x 1033 grams. So the fraction of its mass it loses every year is about 10-13. The Earth’s orbit is 150 million kilometers, and if you multiply that by 10-13 you get about 1.5 centimeters. That’s how much bigger the Earth’s orbit gets every year! Less than an inch. It would take 65,000 years for the Earth to move away one kilometer (I can walk that far in a few minutes). Assuming the mass loss is constant, the Earth has only moved out from the Sun 70,000 km in a billion years! That’s only a few times Earth’s own diameter. Even over its lifetime, the Earth’s orbit hasn’t changed much due to the Sun’s mass loss. To be fair, the Sun’s mass loss may have been higher in the past, but even then the Earth hasn’t moved much from this process.

A Lifetime of Mass Loss

But wait! How much mass has the Sun lost over its lifetime? It loses about 5 or 6 million tons of material every second, and that sounds like a lot.

The Sun is about 4.5 billion years old, and a year is about 31 million seconds long. Multiplying all that out, the Sun has lost a total of about 1024 tons of material. That’s over 100 times the mass of the Earth!

But like I said, the Sun is big. That’s still a tiny fraction of its total mass: Over its lifetime, it’s only lost about 0.05% of its mass. That’s a pretty poor weight loss plan.

But it means that the Sun is good to go for a long, long time yet. It could merrily fuse matter and blow off a solar wind for trillions of years at this rate.

But it won’t. Long before then, conditions in the Sun’s core will change. It will run out of hydrogen to use for nuclear fuel, swell up into a red giant, consume Mercury and Venus (gaining some mass back), fry the Earth, then blow off a far more intense solar wind. It’ll shed matter at a rate that will completely outstrip a lifetime of dieting, losing half its mass in just a few million years.

After that all that will be left is a white dwarf; a hot, dense, Earth-sized ball of material that will slowly cool over billions of years and fade away.

If there’s a life lesson about living for today, diets, and thinking in very long timescales, you’re free to find it for yourself. As for me, I think I’ll go out on my bike now and enjoy some sunshine. There’s only a few billion years of it left.

[I’ve thought about writing this article for a long, long time, but a tweet by mxyzplx made me think about it again. I made a note for myself, and I’m glad I finally wrote this up. The Sun lost over 100 trillion tons of mass in the meantime. I need to schedule myself better.

Also, if you like thinking about stuff like this, I give a lot more detail about the Sun’s aging in my book, Death from the Skies!]

Categories: Astronomy Headlines

Zzzzzzzap! And Whooooosh!

Sun, 07/13/2014 - 04:30

I missed it when it was originally posted last week, but thanks to IFLS I saw this very cool Vine video taken by International Space Station astronaut Reid Wiseman, showing lightning flashes inside a cloud as he sailed hundreds of kilometers above:

If you like the video, I have a few more animations of storms and such as seen from the ISS. Seeing something like that — lightning flashes from above — would almost be worth the body-wracking nausea I’d certainly get if I went into space. Almost.

Not only that, but Wiseman’s fellow astronaut Alex Gerst posted his first time-lapse animation from space, showing stars rising over the Earth’s limb with the Canadian robot arm hanging in the foreground… and if you look just to the right of center at the 2-second mark, you’ll see a streak appear for a split second. Gerst caught a meteor in his very first animation!

You should follow both Gerst and Wiseman on Twitter. And you know what? Read Wiseman’s bio, and see what kind of person gets to go to space. I think you’ll find it… enlightening.

Categories: Astronomy Headlines

… and Robin Laid an Egg

Sat, 07/12/2014 - 06:30

I haven’t done a Caturday post in a while (do the kids these days still do that with their LOLing and I Can’t Even-ing?), so why not. We’ve had a blessed event at Chez BA and I love to share.

On the corner of our garage, tucked away on an eave, there’s a bird’s nest. We think it was originally made by some house finches a few years back; they were the first ones we saw use it (and they do like our abode). Every year a mated pair uses it, then eventually flies away, either having successfully hatched chicks or not (we’re pretty sure other birds get the chicks, maybe even before they hatch — Nature, red in tooth and claw and all that).

This year, a pair of robins took up residence (possibly the same pair that did so in 2012). It took a long time for them to do what bird and bees do, but eventually we found a piece of eggshell on the ground. Then, a couple of days later, we saw this:

Yay! Ugly bugger, but not every baby can be cute.

There are at three chicks that have hatched, and you can see two here:

And I know, in that first picture the chick doesn’t even look alive. But we’ve had some hot days here, and it was just resting (note the parent’s beak is open, which is one way birds keep cool; they also pant to expel hot air and keep their insides cooler). Just a few minutes before it was begging for food:

That shot cracks me up. I just saw all three with their heads up and beaks open. Mom flew in and stuck her whole face down the throat of one, so it looks like they’re getting fed pretty well.

We also have a nest in another part of the eaves with swifts in it. Those are very territorial birds; whenever we leave the door they fly around making rapid high-pitched noises at us. They’re lovely, though, and eat bugs, which I’m all for. They’ve made our house their home before, too. They do poop a lot, though, so when they’re all done the nest will come down.

It’s kinda nice to help out the neighbors sometimes, but honestly, they need to clean up after themselves. I wish they had signed the HOA contract.

Categories: Astronomy Headlines

Royal Greenwich Observatory's Astrophotographer of the Year Contest

Fri, 07/11/2014 - 04:00

I’m always excited when it’s time for the Royal Greenwich Observatory’s annual Astronomy Photographer of the Year contest. Being a hugely prestigious observatory, it of course receives a dizzying array of astonishing pictures of the Universe around us. It’s always a pleasure to look through them.

This year a record 2500 entries were submitted, and from this they culled just 19 images to be on their short list for the prizes in the various categories, which include Earth and Space, Our Solar System, Deep Space, and Young Astronomy Photographer of the Year.

All 19 are magnificent, but I picked just a few I liked in particular to show you here. You can see them on the RGO site, and if you have a lot of spare time you can peruse all 2500 submission on Flickr. Winners will be announced on Sept. 14, 2014, and will be part of an exhibition at RGO starting Sep. 18. If you’re in England, go look!

Until then, here are a few of the finalists.

Occultation of Jupiter

On Dec. 25, 2012, the Moon passed in front of Jupiter — what astronomers call an occultation — as seen from Earth. Sebastián Guillermaz captured the pair moments before the Moon covered the more distant planet. I love this shot, especially since it was done during the daytime.

Heart of the Scorpion

Regular readers may recognize the name Rolf Wahl Olsen; he’s been featured on my blog before for his spectacular images of Beta Pictoris and Centaurus A (as well as spotting what may be a giant hexagon on Neptune). For RGO, he submitted this gorgeous shot of the Rho Ophiuchi cloud complex, a ridiculously beautiful star-forming nebula about 450 light years away. Dust in the complex reflects the blue light from a massive nearby star in one part, while absorbing light from objects behind it in another.

Geminid Fireball

The Geminid meteor shower is one of the year’s best, peaking in December. This may be my favorite picture taken of one, not the least of which because I recognized it immediately as having my hometown Boulder Flatirons in the foreground! It was taken by local (to me) photographer Patrick Cullis in 2012. Jupiter is the bright “star” in the center, and you can also see the Pleiades star cluster near it with Orion on the left.

Father-Son Comet

One of my passions is sharing my love and joy of astronomy, so how could I not show you this lovely shot by Chris Cook of a silhouetted father showing his son the bright comet C/2011 L4 (Pan-STARRS) glowing in the twilight sky? In 2013 the comet put on quite a show, but this image captures much of why I do what I do.

Surprise Aurora

Tommy Richardsen was about to pack up and leave a photography shoot when a huge and bright auroral display lit up the sky over Nordreisa, Norway. He was able to capture this phenomenal picture of the lights… even while his brother (seen on the right) scrabbled to get his own camera ready. [Note: Annaliese Possberg, whose work I've featured on the blog before, also has a stunning picture of an aurora in the RGO shortlist as well.]

Stellar Violence in Red and Blue

This jaw-dropping image by Mark Hanson shows the nebula NGC 6888, the result of fierce winds of subatomic particles blown off by the star WR 136, a massive blue monster a quarter million times more luminous than our Sun. The nebula is the result of a previously ejected wind of material being slammed by faster matter ejected more recently. Catch this object while you can: In a few million years WR 136 will explode, sending out much faster material which will sweep outward and destroy the nebula as we see it now.

At the Core of the Heart

IC 1805, also called the Heart Nebula for obvious reasons, is a star-forming cloud of gas about 7500 light years away. Massive stars born inside the nebula emit powerful winds of material as well as copious amounts of ultraviolet radiation. These erode away the nebula from the inside-out, creating a vast cavity in the cloud, and sculpt bizarre and beautiful shapes as well. The fingers, chevrons, and spindles you can see in this photo by Ivan Eder show this process at work deep in the heart of the Heart.

Categories: Astronomy Headlines

NASA Launches a New Eye on Carbon Dioxide

Thu, 07/10/2014 - 04:30

On Wednesday July 2, 2014, NASA launched a new satellite into orbit: The Orbiting Carbon Observatory-2*, designed to study atmospheric carbon dioxide. OCO-2 will be able to measure the levels of CO2 in our air with incredible accuracy and on very small regional scales, something that’s never been able to be done before.

Carbon dioxide is a greenhouse gas: It lets visible light from the Sun pass through the air to heat the Earth, but it absorbs some of the infrared light the Earth emits as it warms. This traps a small but extra amount of heat in the Earth’s air, causing global warming. There are other greenhouse gases, like methane and water vapor, but in general over time they stay constant; humans dump a huge amount of extra CO2 into the air — 30 billion tons per year; yes, that’s billion with a b — and it’s this extra amount that’s causing us so much grief. The level of CO2 in our atmosphere is now 150% of where it was at the beginning of the industrial age, and this is what’s causing the sharp and quite alarming jump in global temperatures over the past century or so.

NASA is very concerned with measuring global warming and the incipient change in our climate, and that’s why OCO-2 was launched. It will take an astonishing 24 measurements every second, getting over a million observations per day. It’s very sensitive to cloud cover (which can compromise the measurements) so it should get about 100,000 usable observations every day in its three-square-kilometer field of view. That’s an amazingly high resolution both in time and space, and will give us an excellent view of the sources and sinks of CO2 over the planet.

The launch was attended by photographers Jeff Sullivan and Lori Hibbett, who got fantastic shots of it. Sullivan created a lovely time-lapse video of the night:

I’m very pleased this satellite is on the job. Global warming may be the single biggest immediate threat humanity faces, and there’s still much to learn about how it works, what effects it will have, and what we can do to stop or at least minimize its effects.

My congratulations to NASA and to JPL, and to the entire OCO-2 team. Let’s hope this will be another big step in helping us save our future.

* The first OCO was lost in a launch failure in 2009; it didn’t achieve orbit and burned up over the Indian Ocean.

Categories: Astronomy Headlines

The View Is Getting Clearer

Wed, 07/09/2014 - 08:21

I have some good news, and some forehead-slappy news.

First, the good news: Sherri Shepherd and Jenny McCarthy are leaving the daytime talk show The View.


I’ve had serious problems with Shepherd for years; back in 2007 I called her out for what can charitably be called profound ignorance on some basic matters (like—and I’m serious—not knowing the Earth is round, claiming that nothing predated Christianity, and being a Young-Earth creationist).

Given that this is a talk show where the panel discusses various current events and offers up opinions, I have long said she’s an inappropriate person to have on. I’m generally understanding of people having opinions with which I disagree if they come to those conclusions in good faith (if you’ll pardon the expression), even if they’re based on bad evidence—everyone has their own beliefs that are illogical or even irrational. And certainly if everyone always agreed on everything it wouldn’t be a very interesting show to watch (or a fun planet to live on).

But there’s only so much ignorance I think a viewer should be asked to tolerate. Shepherd, in my own opinion, was well past that limit.

As for McCarthy, well, her vociferous and glaringly wrong stance against vaccines leaps her way to the front of the pack of people who needn’t be given a voice on television. I was clear about this when she was hired for The View, and I was even more clear when—in a twist that would make Orwell proud—she claimed she wasn’t anti-vaccination. Her influence on the anti-vax movement presents a threat to public health, and anti-vax beliefs are causing huge spikes in preventable diseases like measles and whooping cough.

So yes, I’m glad McCarthy’s leaving a TV show that has an audience of millions of people, many of whom are young mothers with vaccination-age children. However, sadly, I’m also quite sure she will find some other soapbox from which she can peddle her nonsense. There’s no lack of such venues in today’s media.

And now the forehead-slappiness: Apropos of apparently nothing, Sarah Palin is throwing her hat in the ring to be on the show. It doesn’t sound like ABC invited her, and Palin is well-known for, um, self-promotion, so I doubt there’s any weight to this. It would be, in my opinion, a wash to lose Shepherd and McCarthy and gain Palin; the former governor of Alaska has made creationist noises before, and honestly has hardly said one rational thing since getting into the public eye years ago. Her latest step in bizarro land is to unironically call for President Obama’s impeachment for “dereliction of duty,” even though she herself quit the office of governor in the middle of a term after numerous ethics investigations. So, yeah.

Anyway, I know in the long term all this host shuffling on a daytime TV talk show doesn’t mean a huge amount, but I do think it means something. A lot of folks watch TV, of course, and millions still get a lot of their news and information from shows like The View. That means the producers, in turn, have responsibility for what they say and do. Hiring people to give opinions who are known mostly for their advocacy of provable nonsense is not raising the level of discourse in this country, and that’s something we sorely, sorely need.

Tip o’ the moose antlers to Davin Flateau for the info about Palin.

Categories: Astronomy Headlines

Noctilucent Clouds Over the London Eye

Wed, 07/09/2014 - 04:30

My pal Christoph Malin is an astrophotographer, and a very good one; I’ve written about his photos many times.

He sent me an email saying he was in London at a pub, and when he walked out he could scarcely believe his eyes: In downtown London, he could see noctilucent clouds! Being very rarely seen, he quickly set up his camera to get photos of them. He put them together to make this lovely time-lapse animation:

Very cool. I love the composition, with the huge London Eye ferris wheel in the foreground.

As it happens, noctilucent clouds are poorly understood. They appears as thin, wispy clouds (looking very much like tightly constrained cirrus) usually just after sunset as the sky gets dark. The look milky white, shiny (hence the term noctilucent, which means “night-shining”), and sometimes bluish.

They are extremely high up, 76 – 85 kilometers (46 – 51 miles) in altitude. They’re visible due to being lit from beneath by the Sun, but are very faint. That’s why they’re visible only at sunset, when the Sun is well below the horizon to people on the ground but still visible from the cloud’s point of view.

They’re so high up they are actually above the troposphere and stratosphere, where every other kind of cloud forms. Noctilucent clouds exist in the mesosphere, and how they form and evolve isn’t terribly well known. They need dust and water vapor to form, as well as extremely cold temperatures. Several formation mechanisms have been proposed, but it’s not clear which may be most prevalent or even correct.

One reason for the lack of understanding is that they’re a new phenomenon; none has ever been reported before 1885. An intriguing possibility is that they are related to global warming, though this (again) is not well known. I suggest reading the Wikipedia page on noctilucent clouds; it gives a good description and has many links you can follow down the rabbit hole.

And now I have something to add to my list, including a total solar eclipse and an aurora: Things I really want to see but still haven’t yet. I’ve really got get moving on this.

Categories: Astronomy Headlines

Typhoon Neoguri Takes Aim on Japan

Tue, 07/08/2014 - 09:40

People on the main island of Japan are preparing to get hit by the strongest cyclone the Western Pacific has seen in the 2014 season: Typhoon Neoguri. It has already passed over Okinawa, and its 190 kilometer per hour (118 mh) gusts left widespread damage and at least one person dead.

The good news is that it’s drawing in dry air, which is weakening the system; cyclones like this need warm moisture for power. As I write this, its sustained winds are clocked at about 105 kph (66 mph), still very strong. The size of the typhoon is incredible; it's easily thousands of kilometers across. Evacuations have been advised for hundreds of thousands of people in Japan, and tens of thousands are without power.

Over the past day astronauts on board the International Space Station have passed over the typhoon, and they have taken astonishing pictures of the storm system. As always, pictures like these are amazingly beautiful, but never doubt for a second that what you are seeing is as destructive and dangerous as it is awe-inspiring and lovely.

From a Distance

As the ISS approaches the storm, Neoguri is seen from thousands of kilometers away on the limb of the Earth. As astronaut Alexander Gerst exclaimed, “The #SuperTyphoonNeoguri did not even fit in our fisheye lens view. I have never seen anything like this.”

Feeder Bands

As the station passed over the outskirts of the typhoon, the spiral “feeder bands” were prominent. These are squalls of rain showers fed by warm ocean water, and can get very well-defined as the storm gets stronger. The long, thin streamers pointing away from the center are cirrus outflow clouds, well above the spiral bands and moving outward. Note the Russian spacecraft in the foreground, used to transport astronauts and supplies to and from the ISS.

Galactic Cyclone

Another, slightly different view of the feeder bands shows massive convective storms along them, where warm air rises to form giant cumulonimbus clouds (towering columns shaped like cauliflower). Although the physics is very different, the similarity to the arms of a spiral galaxy is striking.

Down the Eye

By an orbital coincidence, the space station passed directly over the eye of the typhoon, where the air pressure is lowest. Warm air near the ocean surface from outside the eye wall moves inward and upward, spreading out over the top of the typhoon. Inside the eye air is dropping down, where it dries out and becomes clear. It’s relatively calm inside the eye, with the fiercest winds in the eye wall.

The Eye of the Storm

A closer view of the eye shows details and shadows inside. Gerst estimates the size to be 65 kilometers (40 miles) in diameter.

Oblique Eye

As the ISS moved on, astronauts got an oblique view of the eye. This makes depth more obvious and the vertical structures in the inner feeder bands and eye wall easier to see.


NASA’s Aqua satellite took this jaw-dropping shot of the typhoon on July 8, 2014, at 05:00 UTC. To the left of the eye is the coast of China, and the island of Taiwan is to the eye's lower left. The sheer size of the typhoon is amazing.

The Path of Neoguri

The European satellites MT-SAT and Meteosat-7 took infrared images that were mapped onto NASA's Blue Marble Next Generation ground map to create a time-lapse animation of the path of Neoguri over the course of July 4 to July 8, 2014.

The latest satellite images can be found at the Japan Meteorological Agency, and updates at Weather Underground. For more information on Twitter, follow astronauts Reid Wiseman and Alexander Gerst, the EUMETSAT group, and NASAGoddardPix.

For everyone in Japan, please stay safe.  

Categories: Astronomy Headlines

Climate Change Is a Threat to National Security

Tue, 07/08/2014 - 08:00

Global warming is real, and we’re starting to feel the physical effects now. It’s difficult to pin any one event on a warming world; it’s like playing craps with a pair of loaded die. That 12 you rolled may have been random, or it may have been because the dice are very slightly weighted. You have to throw a lot of rolls before the effects are seen with any certainty.

But these physical effects on our planet are just the start. Droughts, fires, more extreme weather, sea level rise, ocean acidification … these are just the primary, direct consequences as our planet gets hotter.

But these will have further effects. Starvation, mass migration, rise of disease, species extinction, and collapse of infrastructure follow these primary effects. These will profoundly affect people, and that means politics will play its role, from the local, tribal level all the way up to nations.

David Titley was a rear admiral in the U.S. Navy, and an expert in climate change and national security. He served on the CNA Corp.'s Military Advisory Board, which recently issued a strongly worded report calling global warming a threat to national security.

Titley wrote an op-ed published in the Pittsburgh Post-Gazette reiterating the need to take this threat seriously. It’s actually pretty simple to understand: A changing world environment means a changing political environment. If some regions stand to lose in the crap shoot of climate change, then they will see the need to take action. Furthermore, as the geophysical landscape literally changes, nations will move to capitalize on it (such as melting Arctic ice opening up shipping lanes, and, ironically, more places to drill for oil). These are things our government must pay attention to, and must make plans for.

Of course, as I’ve written about before, Republicans in Congress added an amendment to a Department of Defense funding bill specifically forbidding money be spent on looking into global warming. Ironically, for all their nationalistic claims, their actions put our nation in very real jeopardy.

Once you deny reality, the fantasy you spin can be very dangerous.

And, of course, they are cheered on by the Noise Machine. The latest is by perennial reality-stomper David Rose, who would probably deny the Earth was warming up when the Sun turns into a red giant and fills half the sky. In the Daily Mail (I know, wrapping a fish in the Mail is an insult to the fish, but it’s sadly widely read) he penned his usual nonsense, this time a ridiculous piece about there being more Antarctic sea ice than usual, so how can global warming possibly be real?

Happily John Abraham and Dana Nuccitelli handily destroy this bit of misinformation. The bottom line: Antarctic sea ice comes and goes every year, and a relatively small increase this year does very little to balance the vast loss of Arctic sea ice, or the massive melting we’re seeing in Greenland and Antarctic land ice. Abraham and Nuccitelli correctly point out that screeds like Rose’s are distractions, adding noise to the discussion without adding any real content.

In situations like this, I picture deniers with their backs to a raging forest fire, looking at one tree off to the side that’s not yet aflame, claiming that everything’s OK.

Everything is most certainly not OK. We’re changing the planet, and that’s changing the shape of geopolitics. We need to face that fact, and the sooner the better.

Categories: Astronomy Headlines

Two Big Rocks Pass in the Night

Tue, 07/08/2014 - 04:30

Around the same time Mars and the Moon were making each other’s acquaintance earlier this week, two other solar system bodies were prepping to do the same thing: Ceres and Vesta, the two biggest asteroids in the solar system, got pretty close together, too.

That two-frame animated GIF is from astrophotographer Jerry Lodriguss, who took the two pictures an hour apart when the asteroids were separated by about 10 arcminutes, about 1/3rd the apparent diameter of the Moon on the sky. In that short time their motion was visible against the fixed background stars.

When I say “their motion”, I’m actually including a lot of hidden things. Both orbit the Sun, of course; Ceres is about 400 million km from the Sun, and Vesta 350 million. Ceres makes one orbit in 4.6 years; Vesta 3.6.

But there’s more! The Earth is orbiting the Sun, faster than either asteroid. We sit on Earth and sweep past them, like a passenger in a car passing cars in other lanes. You have to account for everyone’s movement if you want to figure out just how the two asteroids move and send spaceships there.

Which, in fact, we have done: NASA sent the Dawn spacecraft to visit Vesta, and it stayed in orbit around the asteroid for a year. It left Vesta in late 2012 and is now approaching Ceres. It’ll arrive and go into orbit in February 2015.

From Earth the asteroids are barely bigger than dots (even to Hubble). But when you go there they look like this:

Yeah. That’s what Vesta looks like when you’re a few hundred kilometers away. Right now we only have blurry image of Ceres, but in a few months that will change a lot. What will we see? If we knew that, we wouldn’t have to send probes there.

Space exploration is pretty cool. It turns lights in the sky into worlds! Each different, each wondrous, each with so much to teach us.

And they’re fun to watch, too.

Categories: Astronomy Headlines