Bad Astronomy Blog

How to Make a Rubber Ducky Comet

10 hours 49 min ago

Before we knew what comets and asteroids looked like up close, it was popular (at least in media) to imagine them as roughly spherical, maybe a bit lumpy.

The reality was way stranger. The first comet seen up close, Halley’s, was actually more elongated, like a rock you might find in your back yard. As we sent space probes to more of these celestial flotsam, we found most were oddly shaped, and some downright bizarre: a double-lobed bowling pin shape kept popping up. Hartley 2, Wild 2, Kleopatra (which looks like a cartoon dog bone!), and now, most recently, 67P/Churyumov-Gerasimenko, the new home of the Rosetta probe. The solid part of this comet looks like a rubber ducky, with a large, flattish lobe connected somewhat off-center to a smaller, more rounded chunk.

What gives?

I’ve written about this before. My original thinking was that these shapes are due to a slow collision by two bodies, which manage to stick together. 67P, however, has many features that look more like it was one object that has been eroding away in the middle, creating the double-lobed shape.

Now it looks like the former was more important than the latter. A new study has just been published showing that slow-speed collisions between two objects can create the shapes we see.

The researchers used three-dimensional modeling to determine how this could work, and the video above shows a representative example. A larger and small body collide slightly off-center, causing material from the smaller one to splash on to the bigger one, and slowing their relative speed. Their mutual (weak) gravity draws them together again about a day later, and they wind up sticking to each other, forming the familiar two-lobed morphology.

This also explains a peculiar layering seen in some comets, due to the splashing of material from one object to the other. It’s nice when a single model can explain more than one physical characteristic.

Collisions like this may have been common in the very early solar system, when there were a lot more objects out there; as the giant planets formed after a few tens of millions of years, their powerful gravity wound up eliminating many of those comets and asteroids (either by drawing them in and assimilating them, flinging them away and ejecting them from the solar system, or dropping them down in to the inner solar system in an event called the Late Heavy Bombardment, the scars of which are still visible on the Moon today). A collision like this would be rare now.

If this scenario is correct, then, looking at 67P, I have to think both processes are at work there. It originally formed as a slow speed collision, and then erosive processes have been at work for quite some time since. The cliffs on the smaller lobe appear to be due to cleaving or calving of the comet there, and you wouldn’t expect such large flat features after a collision.

That wouldn’t surprise me at all; a lot of the features we see in astronomical objects in the solar system today are the result of many processes, some of them ongoing. These things have been around a long time, after all, and there have been periods of fairly intense activity since the whole place formed some 4.56 billion years ago. It’s incredibly rare to find an intact, pristine time capsule from that time so long ago, and we have to be aware that, in simple terms, stuff happens. So to speak. 

If this model is true, it means that collisions like this were common (since we see double lobes so often) and that most would’ve happened a long time ago. This may be testable by examining these dog bone/rubber ducky/bowling pin objects and seeing if we can determine just when they may have assumed these shapes. If it happened right after the solar system formed, then great! If not, well, then we’ll have to modify the hypothesis or abandon it.

Such is science. We sometimes have to follow a path to a wrong idea to make sure it’s not right. But even then, it may be salvageable, and at worst we’ve learned something anyway. Science is pretty cool that way.

Categories: Astronomy Headlines

Crash Course Astronomy: Uranus and Neptune

Fri, 05/29/2015 - 04:30

I’m not gonna lie to you: This is the best cold open of any episode we’ve done so far. I made myself laugh writing it.

Before you comment, PLEASE READ THE FOOTNOTE ON THIS ARTICLE. And if you still feel the need to comment, remember, neither you nor I is funnier than Futurama.

About that pronunciation, this may help as well.

I’ve also written about those giant storms that erupted in Uranus’s atmosphere, an odd hypothesis about why the planet is tipped over, and an interesting claim that Herschel may have seen the rings of Uranus!

As for Neptune, some articles that might interest you: A new moon found by Hubble, a celebration of the completion of one Neptunian orbit since it was discovered in 1846 (including some lovely Hubble pictures), that time the New Horizons Pluto probe saw Neptune and Triton, and what I consider the single finest picture of Neptune that exists.

Also? Neptune is really far away.

Categories: Astronomy Headlines

Pluto – 47 Days

Thu, 05/28/2015 - 04:00

In 47 days, the New Horizons spacecraft will zip past Pluto and its moons at a relative speed of 14 kilometers per second. As of right now, there’s more than 50 million km still to go.

But earlier in May, the probe turned its cameras toward Pluto and took a series of images. They’re still pixelated, but wow.

As you can see, surface features are getting easier to discern (note that a different part of Pluto was seen by the probe on each day, so you're seeing different features). It’s not just light and dark patches, but they have some shape to them as well. It actually reminds me a bit of seeing Mars through a small ‘scope. Note that on the May 10th image there appears to be a dark chunk taken out of Pluto’s side; that’s an illusion due to that spot being particularly dark; it blends in with the blackness of space and fools your eye into thinking Pluto’s missing a piece.

These images are considerably better than what we saw in April, too:

Not bad. As before, the new images have been carefully planned and post-processed to increase their resolution. These shots were taken from 80, 77, and 75 million km away and are already in many ways better than we can get even with Hubble.

So stay tuned. Every day, New Horizons gets over a million kilometers closer to Pluto, and well be getting some amazing views, culminating in the flyby on July 14. What delights and wonders will we see then?

Categories: Astronomy Headlines

All These Worlds Are Yours …

Wed, 05/27/2015 - 09:27

On Tuesday, NASA announced the scientific research instruments that will be installed on board the 2020s mission headed for Jupiter’s moon Europa.

The moon has a thick ice shell covering an undersurface ocean, and there’s a lot of interesting chemistry going on in that water. We don’t know if there’s life there, or even if the ocean is habitable, but it’s an incredibly enticing destination. That’s why the (currently not-yet-named) mission is headed that way.

And it’ll have quite the suite of instruments onboard, too: a camera that will map almost the entire moon with 50 meter resolution (and some spots with 0.5 meter resolution!), radar that can determine the thickness of the ice and ocean, a thermal (heat) mapper, an ultraviolet camera, and much more. You can read about them on the NASA press release and in the Planetary Society blog post by Casey Dreier.

I’m excited about this; the NASA fiscal year 2016 budget has $30 million set aside to develop the mission. If things go well, there will be more in the years to come. Europa is one of the three best places to look for life in the solar system—the other two being Saturn’s moons Titan and Enceladus, and a mission there would take longer, be bigger, and cost more money. As much as I want to see more of those worlds, I think going to Europa is a good first step. And if we do find something biologically intriguing there, we’ll be in a better place to send more missions.

Now pardon me while I take something of a left turn.

I follow quite a few planetary science folks on Twitter, and it was Christmas for a lot of them on Tuesday. My feed was nonstop chatter about the science that’ll be done at Europa. Someone mentioned that of the nine instruments chosen for the mission, three of them have women as principal investigators (the person in charge of the project). I checked, and sure enough, it’s true.

Female PIs are not exactly unheard of in NASA, but they’re certainly not at a 50-50 ratio with men (I worked on the proposal for the NuSTAR mission, the first NASA astrophysics observatory with a woman at the helm, and that launched just three years ago). There is nowhere near parity in the sexes at most scientific institutions, so I like to support and highlight women in the field when I can (for example, Sally Ride’s birthday on Tuesday).

So in the interest of raising a bit of awareness, I tweeted about it:

Seems clear enough. But I got a couple of angry tweets in response; both accused me of being sexist, seeming to think I was somehow amazed that women could actually run NASA science instruments!

Um. I know that we live in an outrage culture, and I also know just how things get misinterpreted on the ‘Net. Even so that struck me as a bit of a stretch.

I followed up the tweet with another one expressing my own bafflement as to how I could be accused of that when I was supporting women (especially given the context of my many tweets and blog posts supporting women in STEM), and then got responses saying those first responses must’ve been from, gasp, feminists.

At that point my desk got up close and personal with my forehead. I think pursuing this line of thought is going to lead to an ever-amplified Möbius strip of hollering Internuttery, so I’ll leave it to you to follow it if you so choose. Tread carefully.

But this whole thing brought up a point that is worth thinking about. As I said, in most sciences there isn’t parity between men and women. Study after study show that this must have some sort of social basis; women are no less or more suited for science than men. I am no expert on the details, and I leave that for those who are doing the research to investigate. But the conclusion remains.

In an ideal world, science would be science, and anyone of whatever sex who does it for the betterment of humanity is fine by me.

But we don’t live in an ideal world, and we must be practical. Women are not staying in sciences, they aren’t treated the same as men (and it’s generally in a negative sense, unless you’ve been living somewhere under the crust of the Earth for the past, oh, say, century or two), and they are at a disadvantage in many ways compared with their male colleagues. Not an intellectual disadvantage, not a performance disadvantage, not any intrinsic disadvantage, but a socially-engineered one.

If all things are equal except for the societal thing, then how about we fix the societal thing?

One way to do that is to simply make people aware of it. I’m not exactly the swiftest boat on the lake when it comes to things like this, and it took me a long time, but I’m coming around to the notion that sexism pervades everything in our culture.* If I can figure that out (due to the raising of my own awareness by my friends and colleagues), then so can others, and if I can help, well then I will.

And so I do what I can. There may come a time when parity or a close approximation thereof can be achieved. When that day arrives then we won’t need to note when women make strides toward equality, and an achievement in science will be simply that, rather than segregated by the sex of the achiever. But that day is not yet here.

In the meantime we can all work toward it, and work toward the bigger goals of science at the same time. And when we do, we need to remember the mistakes of the past, so that we don’t repeat them—social equality is a dynamic equilibrium; we need to keep working at it to maintain it, lest the scales tip once again.

There are entire worlds to explore out there, folks. Let’s do what we can so we can all explore them.

*It’s more fair to say that sexism is one of the main biases pervading our culture, along with many others such as racism, homophobia, and a host of other prejudices. That list goes on and on, and it might be easier just to say there’s a bias against anything that isn’t white-cis-Christian-middle-class-male, but I don’t want to lose the main point here.

Categories: Astronomy Headlines

Time-Lapse: Trails End

Wed, 05/27/2015 - 04:30

Randy Halverson is an amazing astrophotographer, whose gorgeous photos and time-lapse animations have graced this blog numerous times.

His time-lapses show landscapes lit by the setting Sun, roaring thunderstorms, and of course the night sky wheeling overhead… and his newest, Trails End, is magnificent.  He’s posted a trailer for it, and wow. Make sure this is set to the highest resolution you can handle (it’s filmed in 4k!), make it full screen, and turn the volume up.

If you’re heart doesn’t pound at 1:30 when that massive thunderstorm rolls in, then I can’t help you.

As I watched, I was amused to see quite a few geosynchronous satellites in the sky sequences. These are satellite in orbits about 40,000 km from the Earth’s center; in such an orbit they take 24 hours to circle the Earth once, so they appear to stay in more-or-less the same spot in the sky relative to the ground. A trick to finding them in the shots is to not focus on any one part of the sky, but let your gaze take in the whole frame. Stars will move, but the geosynch sats won’t.

At 2:48 I noticed something odd, and Halverson confirmed it: He caught a rocket boosting some satellites into orbit. Also, at 3:20, there’s a meteor that leaves behind a persistent train, a glowing vapor trail. The video slows there for a moment to give you a chance to see it. Very very cool.

Remember, this is just the trailer for the much longer version that’s shot in ultra-high def. If you have a high-res monitor (or a 4k TV!) you could do a lot worse than getting this movie

Categories: Astronomy Headlines

Google Doodle Celebrates Sally Ride's 64th Birthday

Tue, 05/26/2015 - 10:15

Today, American astronaut Sally Ride would have have been 64 years old.

She died in 2012, but her work lives on as an inspiration to young women who want to touch the stars. Ride was indefatigable in promoting education, in promoting the need to explore space, and working to get girls more involved with science, technology, engineering and mathematics. As the first American woman in space her place in history was secure, but she knew what this implied for her as a role model, and maximized that leverage.

Google has helped promote her message today in a series of lovely Doodles, animated images that come up when you open the home page of the search engine. This one is my favorite.

Rather self-explanatory, isn't it? There are five in total; refresh the Google home page to see them all.

Dr. Ride was immortalized when NASA named the GRAIL spacecraft impact site after her. But her legacy was secured by her own doing, by her actions. And we thank her for them.

Categories: Astronomy Headlines

BA Video: Close-Up on a Comet

Tue, 05/26/2015 - 09:13

In the 1980s, humanity got its first face-to-face view of a comet when a fleet of spacecraft was sent to visit Comet Halley, which was making its first pass into the inner solar system since 1910. We got never-before-seen close-up glimpses of the nucleus of a comet, the inner solid part that creates the gigantic gas cloud and long, beautiful tail.

Over the years more probes were sent to comets like Tempel 1, Hartley 2, and Wild 2. Each is an individual, and each is weird. But all of those missions were flybys—important but brief.

But now we have the Rosetta spacecraft orbiting the comet 67P/Chuyurmov-Gerasimenko, studying it in detail and over a great length of time. We’ve learned so much about it, but also opened up a Pandora’s box of even deeper mysteries about comets in general, and this comet in particular.

The big one, in my mind, is why it and so many others are shaped like bowling pins: two separate lobes connected by a relatively thin neck of material. We still don’t know when it comes to 67P, but in this week’s Bad Astronomy Video I go over the evidence we have so far.

The Rosetta mission has a nominal lifespan of a year, following 67P as it nears the Sun and becomes more active. There’s a huge amount left to learn, but a corresponding amount we’ll also discover. And that’s one of my favorite facts about science: It’s a jigsaw puzzle with an infinite number of pieces, so the fun of exploration never ends.

For more information about comets, read my article 10 Things You Don’t Know About Comets.

Watch more of Slate’s Bad Astronomy videos with Phil Plait.

Categories: Astronomy Headlines

Climate Change Denial Is a Threat to National Security

Tue, 05/26/2015 - 04:30

First, let me be clear about this reality: Planet Earth is warming because of human activity, because of us, and that is profoundly affecting the climate. There is no honest doubt about this; the overwhelming evidence supports it, so much so that 97% of climate scientists agree on it.

The effects of climate change are profound. We are already seeing more extreme weather, more powerful tropical storms, more wildfires. As the sea level rises coastal populations are threatened, including military bases.

I have been saying for a long time that climate change is a threat to our national security, and it’s long past time to call out those who would deny this as abetting that threat.

President Obama did just this last week, in a speech at the US Coast Guard Academy. My Slate colleague Eric Holthaus wrote all about this, and I strongly urge you to read that article. Obama used words like “negligence” and “dereliction of duty”:

After all, isn’t that the true hallmark of leadership?  When you’re on deck, standing your watch, you stay vigilant.  You plan for every contingency.  And if you see storm clouds gathering, or dangerous shoals ahead, you don't sit back and do nothing.  You take action -- to protect your ship, to keep your crew safe.  Anything less is negligence.  It is a dereliction of duty.  And so, too, with climate change.  Denying it, or refusing to deal with it endangers our national security.  It undermines the readiness of our forces.

This sentiment was reinforced in a tweet from the President:

Take a moment and ponder this. The President of the United States of America said that people who deny the reality of climate change are a threat to national security. And he strongly implied that members of Congress who do so are guilty of dereliction of duty.

I agree. And they do so on the basis of what is at best wrong information, and at worst a passel of lies.

The only doubt is manufactured, sole-sourced by the fossil fuel industry. Senators, Congresscritters, “think tanks”, sponsored by fossil fuel (and using the same tactics as the tobacco industry) — the doubt they sow is as fake as three dollar bill, and just as obvious (and embarrassing). From ridiculous and patently false claims that global warming has slowed, that the world can’t be warming because winter still exists, that (seriously) plants like carbon dioxide so we’re just feeding them; these people’s only purpose is to slow any real progress on fixing the planetary mess we’re in.

And in that way, they are making things far, far worse.

As the latest example, look at an OpEd in Forbes magazine written by Heartland Institute’s James Taylor (yes, that Heartland Institute). Taylor has a history of cherry-picking and distorting results from real climate scientists, and he’s doing the same thing here.

In the OpEd, he claims that global warming has not caused global sea ice retreat. This is a gross distortion of reality. The truth is that in the arctic we’re seeing record low levels of sea ice year after year, including just this year, when in March the north pole saw the lowest maximum ice extent on record.

It takes a very twisted view of the world to claim global warming isn’t doing anything to polar ice not two months after that record was broken. And as we know very, very well, Arctic sea ice is on a long, drastic decline that does not show any signs of recovery at all.

But note how Taylor phrases it, using “global” ice. That includes Antarctic sea ice, but as I have written about over and over again, that is really unfair. Antarctic sea ice is very different than at the north pole; Antarctica is a continent and conditions there are literally polar opposites. The southern sea ice fluctuates quite a bit year to year, and in fact wind-driven snow can be increased by global warming (warmer air can hold more moisture), so glossing over local conditions the way Taylor does is at best misleading.

And in actual fact, land ice in Antarctica is melting away extremely rapidly, and worldwide we’re losing 450 billion tons of land ice every year.

That doesn’t sound at all like what Taylor is claiming, does it? I guess he doesn’t know (or doesn’t say) that his corporate sponsors are using the ongoing decrease in arctic ice as a reason to explore more drilling sites in north polar waters.

I’ll also note Taylor links to some satellite data from the University of Illinois Polar Research Group to make his claim… and that same group has issued a rebuttal saying Taylor cherry-picked his data and refutes his claim. Oops.

As much as I loathe what Taylor is doing and saying, I reserve my strongest feelings for people like Senator James Inhofe (R-Oklahaoma), my own Senator Cory Gardner (R-Colorado), and virtually all the GOP presidential candidates, who claim with various degrees of head-in-the-sandness that humans aren’t causing global warming.

These people have a sworn duty to protect the people of our nation. What they are doing is the exact opposite in every way. They cut NASA’s funding to investigate climate change. They even cut the Pentagon’s funding to act on it. The Pentagon.

In the medium to long run these politicians are putting us at greater risk from drought, wildfire, extreme weather, and rising sea levels. In the near run they are cruelly crippling our ability to do the kind of research that has made the United States of America a world leader in scientific innovation.

They claim to love this country. But they sure don’t act that way.

I have written about the reality of global warming and the lies of the deniers so often that to list them all would be counterproductive. Instead, here are some highlights that you can use to counter the denial; check links therein to find even more.

How to Lie With Data (or, “Melting Away Global Warming”)
New Observations Confirm Greenland, Antarctica Losing Land Ice Rapidly
The Top of the World Sinks Ever Lower
New Study: Climate Scientists Overwhelmingly Agree Global Warming Is Real and Our Fault
Slaying the Zombie Ideas of Climate Change Denial

… and, of course, always check Skeptical Science when you hear a claim from someone saying global warming isn’t real. The vast, overwhelming amount of the time, that claim is nitrogen-rich.

Categories: Astronomy Headlines

It's Crowded Downtown

Mon, 05/25/2015 - 04:15

Funny. I was thinking I want to just post a big, gorgeous, colorful photo showing a bunch of different astronomical objects in one scene, and then I found a note from Derek Demeter, Planetarium Director at the Seminole State College of Florida. He’s an accomplished astrophotographer, and took this stunning picture of the galactic center last October:

Holy wow! Isn’t that gorgeous? Even better, there’s some very interesting stuff going on here. Let me break it down for you.

This photo was taken of an area of the sky toward the center of our Milky Way galaxy. Like looking downtown from a big city’s suburb, this is the direction where all the action is. The bright pink nebula in the center is M8, the Lagoon Nebula, a star-forming gas cloud roughly 4000-6000 light years away. The pink is due to warm hydrogen, glowing as its energized by the young, hot, massive stars actively bring born in the nebula.

To its upper right is M20, the Trifid Nebula, a smaller but still iconic gas cloud that appears to be trifurcated by three dark lanes of dust that meet in its center. It really does look like a cosmic flower. Note the blue cloud to its upper right; that’s dust reflecting the light from young hot stars (which happen to be blue). It’s roughly the same distance from Earth as the Lagoon.

Below center is the sparkly orange brilliance of Mars. When Demeter took this picture, it was about 250,000,000 km from Earth. For comparison, the Lagoon was about 200 million times farther away.

And all this is superposed on the magnificence of the stars of the Milky. You can pick out thousands of them easily enough… but you may also notice that yellowish, washed out glow suffusing the shot. Those are stars too! Millions of them, billions, all so far away their light merges into a background glow. The blackness in the center of the image is where you see fewer distant stars because their light is blocked by thick clouds of dust; complex organic molecules created when stars are born and when they die. In space it’s ethereally thin, but you’re looking through a lot of space here. It adds up.

Amazing, isn’t it, just how much is here to see? If there’s one thing I’ve learned in all my words immersed in astronomy, it’s this: There is no such thing as just a pretty picture.

Speaking of which, check out more of Demeter's work on his 500px page.

Categories: Astronomy Headlines

Wait. That’s the Same Comet?

Sun, 05/24/2015 - 04:30

The folks at the European Space Agency released a new picture of comet 67P/Churyumov-Gerasimenko, and I have to admit that it threw me.

Huh. That’s the comet? Where’s the second lobe?

For a second I thought we were just seeing it end-on, so that the bi-lobed rubber ducky shape wasn’t obvious. But then I realized the part we’re seeing is too thin; the big bottom lobe is much wider than seen here. I did a bunch of rotations and such in my head, and quickly concluded there’s simply no angle on the comet that would produce this view.

My brain really jammed at that point, and I had to concede: I didn’t understand the photo. I read the accompanying text to find out what was going on, and got a good chuckle. I forgot about the Sun.

Here’s the same photo, with the contrast/brightness wildly stretched:

Aha! The smaller lobe is there, a barely darker black against the black sky. The reason it can’t be seen is that it’s in the bigger lobe’s shadow. And also, the bottom of the bigger lobe is flattened, shaped more like a river rock than a potato. At this angle it looks foreshortened, so that fooled me as well.

I love puzzles, and I love getting as far as I can before going to the answer key, but this still felt a little like cheating, since I couldn’t figure it out all out by myself. Drat!

But there’s one thing I did see I do understand. Look to the left, just below the tip of the lobe. See that luminous line dropping down? Care to guess what that is?

Hint: The plumes you see coming from the comet are actually jets of gas, caused by the Sun heating the ice in the comet, turning it directly into a gas*.

Got it now? That vertical line is the shadow of the solid part of the lobe on the gas surrounding the comet. Comets are so weird: They can cast shadows on themselves!

I’ve spent a lot of my life interpreting astronomical images, squeezing the science out of them by analyzing their shapes, contours, brightness, colors, and more. This picture is a good reminder not to take experience for granted, nor to invest too much confidence in it.

Any of us can be fooled at any time. That’s an uncomfortable but necessary piece of information to always keep in mind.

* Also making it useful for the annual Pacific Tech “Smart People on Ice” show. And yes, I did just watch “Real Genius” for the 300th time the other night. Why do you ask?

Categories: Astronomy Headlines

How Do Clouds Form?

Sat, 05/23/2015 - 04:15

As someone who loves looking at clouds, and may have a somewhat scientifically directed brain, I’m fascinated by the shapes and structures of clouds. Where I live, at the foot of the Rocky Mountains, provides endless examples of them.

I write about them a lot, but I don’t think I’ve ever explained just how clouds form. After all, it’s a little weird: A typical storm cloud can have a mass of millions of tons, yet they float! I know this is because they’re less dense than air, but that still seems weird.

But, if you watch this great video on how clouds form by my friends at Minute Earth, you’ll understand exactly how this all works.

There were two parts in that video that I want to emphasize. One was just why clouds are buoyant; it’s for the same reason a helium balloon is. At a given temperature, a volume of a gas will have the same number of atoms or molecules in it no matter what those atoms or molecules are. Helium atoms have way less mass than oxygen and nitrogen, so it weighs less, so up it goes. And it’s the same for humid air!

The other part was why clouds have flat bottoms. The video makes that really obvious: As you go up in altitude, the temperature of the air drops (this is called the lapse rate, which for some reason is a term I think is really cool). Water vapor (water as a gas) is transparent, so you don’t see that big bubble of rising humid air until gets to the part of the atmosphere where it’s cool enough for the water to condense into droplets (and becomes visible). If the air over a wide area over the ground all reaches that temperature at the same altitude, it forms a plane parallel to the ground. As the humid air rises through that plane it condenses, forming a cloud that is round on top and flat on the bottom. It’s actually a bit of an illusion; the parcel of rising air is still balloon-shaped (very roughly), but you only see it where the water condenses.

I have to admit: I knew all the pieces of this, but hadn’t really put it all together in my head all at once. Seeing it drawn out this way in animated form made it very clear (so to speak, har har).

At the top of this post is a picture of clouds forming with flat bottoms, and you can see their bottoms are all at about the same altitude. I have always thought this would explain why we see the sky as a flattened dome over our heads; A cloud directly overhead is close to us, but one near the horizon is much farther away, giving the sky a flattened look. The perspective effect is strong; you can see how the clouds appear to bunch together when they’re farther away. That’s not real; they’re probably scattered just as much 50 km away as they are overhead, it’s just that when they’re farther away you see more of them in the same area of sky because they appear smaller with distance.

If all of this seems obvious to you, then yay! But I know that many times, when we live our lives in the natural world, there’s a lot of stuff we see, and even a lot of pieces of it we understand. But putting it all together, turning it from a lot of jigsaw puzzle pieces into a single glorious picture, well, sometimes you need someone to show you that part.

If you want more about clouds, then watch this other video by my pal Joe Hanson from It’s Okay To Be Smart. There’s a lot more there.

Tip o’ the brolly to the good folks (who are also friends of mine!) at Science Alert, too, for linking to both videos.

Categories: Astronomy Headlines

Dragon-Eye View of SpaceX Pad Abort Launch

Fri, 05/22/2015 - 11:42

On May 5, 2015, SpaceX tested its launch abort system: A set of powerful rockets on the Dragon space capsule that can pull the Dragon away from the Falcon rocket underneath in case of catastrophe.

SpaceX just released video taken from a camera on the Dragon capsule, and it’s pretty dang dramatic. Come along for the ride:

Whoa. SpaceX said the capsule went from 0 to 160 kph in 1.2 seconds, which is an acceleration of four times Earth’s gravity. It reached a top speed of 550 kph, arcing nearly 1200 meters into the air.

You can see the trunk jettisoned at 0:30 (in a real flight, this sits under the Dragon and contains unpressurized cargo and the capsule’s solar panels). At the time I wondered where the trunk landed after the test; from this it looks like it came down in the water; it looks to me the capsule was already past the shoreline when the trunk jettisoned.

Seconds later the drogue chutes deploy to stabilize the capsule, then the three main parachutes release. Weirdly, the video stops just before the capsule splashes down. Perhaps we’ll see more of that later.

This test was critically important: NASA requires any human-rated vehicle pass stringent tests, including the ability to get astronauts away from the rocket stack in case of emergency. If SpaceX had failed this test, it would have been a major setback to getting Americans back into space on an American rocket. As it happens, things look to have gone pretty well.

There's also video of the test taken from cameras on the ground, and you can see just how fast the capsule blasted away from the pad. 

The SuperDraco thrusters used for this test have double duty with Dragon; besides being there if needed in an emergency, they can be used on-orbit for maneuvering the capsule. SpaceX plans on being ready to put humans into space by 2017. They are also currently building the next generation Falcon Heavy rocket with plans for a test launch later this year.

Edited to add: Slate posted a review of a new biography of SpaceX CEO Elon Musk. I also wrote about meeting Musk during a visit I made to the SpaceX rocket factory earlier this year.

Categories: Astronomy Headlines

Crash Course Astronomy: The Lord of the Rings

Fri, 05/22/2015 - 04:00

Who out there doesn’t need a little more Saturn in their life? I can deliver.

This was a cool one to record. Even though we’d done 17 episodes before, I like to play with the format a little bit. I was a little more relaxed when we shot this, leaning back in the chair more and just having more fun with it. I hope that shows.

I know I’ll get asked about this, so to head the question off: Yes, Saturn’s rings really are thinner to scale than paper, by a lot. I’ve done the math.

For clarity, I’ll note that there are places where Saturn’s rings are thicker than 10 meters; they range up to a kilometer thick in some regions. But bear in mind that’s still compared to their 300,000 km diameter! That’s a heckuva ratio.

And why not: Here’s an article I wrote about what would happen if Saturn made a close approach to Earth, inspired by a very cool video showing what it would look like. You’ll like it.

As for Saturn itself, now is a great time to go out and see it. By a funny coincidence, Saturn is at opposition tonight: That means it’s opposite the Sun in the sky, rising at sunset and setting at sunrise. It’s up all night, and that also means it’s as close to Earth as it will get for the year (about 1.34 billion km). If you want to see the planet for yourself — and oh my, yes you do — the next few weeks are the best time to do it.

Find a local observatory or nearby astronomy club; I imagine they’ll have viewings. I expect some people will be thinking of buying a telescope, too, so read this first!

Saturn through a telescope can be literally life-changing. It changed mine, and it’s done so for others. Go look.

Categories: Astronomy Headlines


Thu, 05/21/2015 - 09:00

I’ve been listening to electronica music for a long time (like, a really long time; as in I have Isao Tomita albums), and it’s interesting to me that variations of it are still popular. I can’t keep up with kids these days (STAY OFF MY ELECTRONS), so when a publicist sent me a note about Jamie XX, well, I’d never heard of him.

But she said the video for his new song “Gosh” has cool planetary visuals, so I figured what the heck. I clicked the link, and I have to admit: Yeah, the video has stunning visuals. It starts slow, so give it a chance.

I have to admit to chuckling when the rotating arm of the spaceship swings into view fully a minute into the video, after the very long approach sequence to Mars. That was well done. And the parts with spaceships and space stations set against the planet’s limb are really beautiful. Not to mention looking down on the dunes, craters, and other landscapes. The bits at the end with water-filled craters are really, really nice, jumping into the future after the planet is terraformed. That was pretty cool.

The music isn’t exactly my cup of tea, but after listening to it a couple of times it grew on me. I have pretty eclectic taste (I’ll listen to the Captain America 2 soundtrack then ABBA then Shostakovich all without a break), but this was still something of a stretch. But I do kinda like it.

And I like that the video is slow, languid, letting you linger over each scene. It’s nice to know that some people making visual art still appreciate simple beauty and give you a chance to soak it in.

And who knows? What’s art today may very well be fact in a century or two. That’s the point.

Categories: Astronomy Headlines

The Cliffs of Churyumov-Gerasimenko

Thu, 05/21/2015 - 04:00

The Rosetta spacecraft hasn’t been in the news much lately, but wow, is it the gift that keeps on giving. Check out this magnificent view of the comet 67P/Churyumov-Gerasimenko, looking past the Seth region on the big lobe to the towering Hathor cliffs on the small one:

Oh, my.

67P is a double-lobed beast, a 4-kilometer-long cosmic rubber ducky. It’s not clear why it (and so many other comets and asteroids) have this bowling pin or dumbbell shape; maybe it’s from two objects colliding slowly and sticking together, or one bigger object slowly eroding away as ice inside the comet gets heated to a gas by sunlight and vents into space.

Those cliffs are a clue, but what they’re telling us isn’t clear. They reach 900 meters high and are striated with linear features, looking very much like the comet has been cleaved right there.

That view is strengthened, perhaps unfairly, when you look at the comet in context. This mosaic shows 67P taken at a different time, but viewed from almost the exact same angle, and the lower left quadrant shows the same part of the comet as seen above:

It really looks like it has a bite taken out of it! It’s not hard to imagine this started off as a more elongated, somewhat cylindrical object, and that over the eons a vent in the side kept getting bigger and bigger, eating away into the body of the comet.

Interestingly, you can see ice doing just that from Seth; if you brighten the top image a bit and drop the contrast, the streams of gas flowing away can be clearly seen.

But all this could be coincidence; the comet is a bizarre, alien landscape, and interpretation is difficult. Our sense of what can happen there may be biased by our more terrestrial experience, and we have to be careful to remember: This is in space, has little gravity, is composed of loosely conglomerated gravel and ice, and is sculpted by escaping gas and the rare impact rather than wind and sea. It’s easy to follow the garden path of reason to a completely wrong conclusion here.

But it’s fun to think about, isn’t it?

Categories: Astronomy Headlines

Get Thing Explainer

Wed, 05/20/2015 - 09:01

A great drawing person has made a book talking about cool stuff using only the ten hundred most used words. He is a friend of mine and very funny and brain-good, and his drawing stuff is a lot of fun to look at. Hundreds of hundreds of hundreds of people love what he does, and I do too. You should buy his new book by touching these red words.

Here is a picture of the cover of his new book:

And here is a picture of one of the drawing things he made about a car that looks at things on the Red World:

Touch these words to make the picture bigger and easier to see.

If you don't understand what I am writing here and why I am doing it this way then you should touch these red words to find out more. My friend has more stuff about his book and when you read it you will understand.

You can order the book early and then get it when it comes out near the end of the year. I really really think you should.

I wrote this using the Up-Goer Five writing help thing.

Categories: Astronomy Headlines

Rainbow Tornado

Wed, 05/20/2015 - 04:00

Last year, I thought myself pretty lucky to catch a lightning bolt zapping across a rainbow while I was taking video of it.

But that was nothing compared with what some storm chasers saw near Eads, Colorado, on May 9, 2015: a tornado forming across a rainbow!


This was taken around 4:30 p.m. The Sun was about still halfway up the sky, putting the top edge of the rainbow just over the horizon. The raindrops forming the rainbow were between the storm chasers and the tornado, so technically the rainbow is in the foreground. Watching the video gives the illusion the rainbow is behind the tornado to me … but that is an illusion.

This tornado (and another nearby) reportedly didn’t do any damage or cause any injuries, but there were some in Texas spawned by the same massive system that did. I’ve never seen a tornado, nor do I feel the overwhelming need to. It’s rare to get them just where I live in Colorado, but towns nearby get their share. I’m glad we’re getting so much rain here this spring (especially given that Colorado supplies so much water to regions west of us that so desperately need it), but I also hope we don’t get the dangerous conditions that so often occur with it in this area … even if it sometimes gives us a glimpse of rare beauty.

Tip o' the storm cellar door to Geekologie.

Categories: Astronomy Headlines

Sen: Lunar Cartography

Tue, 05/19/2015 - 08:58

The United States Geological Survey just released two incredible and incredibly beautiful maps of the Moon, made using data from the Lunar Reconnaissance Orbiter. They are highly detailed and quite lovingly produced. 

I wrote about them for my twice-monthly column at (subscription required). The USGS site says they will be available as prints, but they're not online to order just yet. Still, the PDFs are very nice and, I'd think, very handy. If it ever stops raining here in Colorado, I'd like to compare them to the view through the eyepiece!

Categories: Astronomy Headlines

Tripping the Light: Fantastic!

Tue, 05/19/2015 - 04:00

N.B. Scroll to the bottom for launch info.

Tomorrow, if all goes well, The Planetary Society will test a new technology that could open up a new way to explore the solar system. On board a United Launch Alliance Atlas V is a tiny cubesat, a parallelepiped just 10 x 10 x 30 cm in size — roughly the same size as a loaf of sandwich bread.

Packed into that tiny enclosure is a prototype called LightSail, a spacecraft that carries no fuel. Instead, it will use sunlight to propel it.

Light of any kind can exert pressure, called radiation pressure, when it interacts with matter. The amount is incredibly small, but it’s there. And if you’re out in space, where sunlight is eternal and there’s no atmosphere to counteract it, that pressure exerts a teeny force that can be used to accelerate a probe.

To be useful, you need a probe that has very little mass (to reduce overcoming its own inertia) but a lot of surface area, to catch as much sunlight as possible. This naturally leads to the idea of a light sail; a huge but very thin sail made of Mylar (4.5 microns thick; a human hair is about 20 times thicker). Attach this to a small satellite and you have yourself a space probe.

To be sure, the acceleration is small, and it takes a while to build up speed, but that acceleration can be applied over long periods of time. Months. Interplanetary speeds are achievable this way!

This test is sponsored by The Planetary Society, whose purpose for existence is to “Empower the world's citizens to advance space science and exploration.” They do a lot of great work educating the public and advocating for space exploration, including funding actual projects.

LightSail is one of them. The launch Wednesday is to test a prototype of this technology and show that it can be deployed—it won’t be up high enough in orbit to overcome the very tiny but persistent drag caused by the very thin atmosphere. But if this goes as planned, the next step will be to build the full-fledged LightSail demonstration craft itself in 2016.

Here, let Bill Nye, CEO of The Planetary Society, explain:

This is amazing stuff, right out of science fiction… but it’s fact. By all accounts, this should work. The prototype should go a long way toward proving that.

As for the next step, The Planetary Society needs your help. They’ve raised most of the funds needed to build the full-up LightSail for next year, but they’re looking for donations from the public to complete it. They’ve set up a KickStarter for it that blew through the $200,000 initial goal pretty quickly, but the more the merrier. If you’ve got a few extra bucks lying around, you could do worse than help a group of really good folks try to create a new way to explore the solar system.

ULA will webcast the launch of the LightSail prototype live. The exact time of the launch window has not yet been announced, but the launch is scheduled between 14:45 to 18:45 UTC (10:45 – 2:45 p.m. Eastern time). You can keep up with the latest news and articles about the LightSail project at The Planetary Society, too.

Categories: Astronomy Headlines

BA Video: How Likely Are We to Die From an Asteroid Impact?

Mon, 05/18/2015 - 10:22

I guess today is Debunk Monday.

This morning I wrote about why a planetary alignment can’t cause earthquakes. In it I also mention that every time an asteroid passes Earth there are a bunch of breathless articles implying (or outright stating) that scientists are worried it will cause a mass extinction.

The vast majority of these articles are, to be technical, what comes out of the south end of a north-facing bull.

However, the threat of an asteroid impact causing harm is quite real, as I’ve written about many times. It’s a cause of concern among scientists, but translating that into realistic action by the public can be tricky.

For example, what are the odds that you’ll die in an asteroid impact? It turns out the chance is extremely low, but maybe higher than you might think. And that’s what’s covered in this week’s Bad Astronomy video:

To put it in even more understandable terms: Asteroid impacts are something I’m concerned about, but not something I’m worried about. I think about them, and work toward getting people to understand them, but they don’t keep me awake at night in terror, sweating and staring at the ceiling.

The good news, too, is that they are a threat we can do something about.  

Watch more of Slate’s Bad Astronomy videos with Phil Plait.

Categories: Astronomy Headlines