Bad Astronomy Blog

Four Planets Await After Sunset

5 hours 10 min ago

Right now, in the night sky just after sunset, you have a chance to see three alien worlds at the same time.

Venus and Uranus are currently undergoing a close encounter; tonight (March 5) they’ll be a little over a degree apart, just about three times the width of the full Moon on the sky. Below them, not far away (maybe 10° or so) is red Mars.

To see them look to the west after sunset. It’s best to wait a few minutes for the sky to get dark. Venus is pretty obvious; it’s the third brightest natural object in the sky (after the Sun and Moon). Mars is still fairly bright and easy to spot below it. Uranus, though, is just on the edge of visibility to the naked eye even from dark sites, so you’ll probably need binoculars to spot it. I found it really easy to see last night using mine.

Speaking of last night, the picture above shows Venus and Uranus when I went out to observe. In the photo, Venus is overexposed and Uranus is the dot below it. You can see that Uranus is a bluish-green, too! That’s cool. Venus is a smaller planet, but far closer—about 200 million kilometers away versus Uranus’ 3.1 billion km distance. All told, in the sky Venus looks about 10,000 times brighter than its more distant cousin. Mars, incidentally, is about 340 million km away right now. It’s also smaller than Venus, so looks dimmer, too.

All three were easily visible even in short exposures with my camera (a Canon T4i using a 55-250 mm zoom). Here’s a nice shot I got last night:

It’s a 10-second exposure, so you can see some trailing in the stars and planets due to Earth’s rotation. But Venus and Uranus are visible to the upper left, Mars below them near the bottom of the frame, and a few of the brighter stars in the constellation of Pisces. If you have a camera, give it a shot! I literally propped mine up on a table and just took a bunch of exposures at different settings. It was also -14 C out, so don’t complain.

And hey—if you count the tree in the foreground, then you can see four planets in that picture! Not bad for a quick and dirty (and cold) photo session.

I hope you have clear skies tonight. This is a pretty nice scene to see. And when you’re done, turn around! The Moon rises around 6:30 p.m. local time, with Jupiter high above it, and the bright star Regulus (in Leo) between them.

The show is all over the sky. Go look!

Categories: Astronomy Headlines

Taking a Dusty View

11 hours 29 min ago

I do love an edge-on spiral galaxy. They look so odd!

That image above is from the Hubble Space Telescope and shows NGC 7814, a galaxy about 40 million light-years away. That makes it relatively close as galaxies go! It’s a bit like looking at a house in the next town over. Not really your neighborhood, but not a long haul, either.

The glow you see is the combined light from countless billions of stars, for the most part orbiting the center of the galaxy in a flat disk. It’s not perfectly flat, obviously; you can see it’s puffed up a bit toward the center. That’s normal for spirals; they tend to have a bulge in the middle. Don’t we all.

The dark stuff is what astronomers call dust; complex molecules loaded with carbon. If you like technical terms, it’s also called polycyclic aromatic hydrocarbon. So there you go.

Dust is created when stars are born and when they die; it gets strewn through the flat disk of a spiral, but is also clumped up in knots and filigrees in giant nebulae, clouds that are stellar nurseries.

Dust is opaque, blocking starlight behind it, so when you see a galaxy like this edge on you see it as a thin line bifurcating the galaxy’s equator. NGC 7814 is a fine example of it.

When I see galaxies like this, I sometimes wonder what they would look like if we could see them from a different angle. That’s not possible; we’d have to travel millions of light-years (quintillions of kilometers!) to change our perspective. But … sometimes nature provides. There are, after all, a lot of galaxies in the sky, tipped at all different angles. Finding one that gives us a better angle isn’t that hard.

That’s NGC 6861, also as seen by Hubble. It’s a galaxy similar to NGC 7814, but obviously tipped to our line of sight. Here you can see the dust swirling around the center, as well as the glow of stars. It looks like a spiral, but in fact NGC 6861 is what’s called a lenticular (lens-shaped) galaxy, a sort-of hybrid between a spiral and elliptical galaxy. It has features of both, and may be the result of a collision between two midsize galaxies. NGC 6861 is in a small, tight group of galaxies, so a collision and merger between two of them isn’t far-fetched.

I love the picture; it looks like a flying saucer whizzing by. And it shows an effect I really love: See how the dust looks darker on one side than the other? The galaxy is relatively flat, and we see the dust on the near side (upper left) fairly directly. But there are lots of stars in the galaxy, and we look through them to see the far side; they’re between us and the far side, so we see their glow. This “fills in” the dark dust, making it look somewhat faded compared with the dust on the galaxy’s near side.

This is a pretty common phenomenon in slightly tilted disk galaxies; check out NGC 3521, NGC 7049, and NGC 2841 (seriously: Click those links. The images are spectacular). 

In a lot of objects it can be pretty hard to tell which side is which, but in these cases a little thought shows the way. Studying galaxies is a funny occupation. You can spend a lot of time learning all about one in particular, but you’re stuck with the way it appears. You can’t go there or change your perspective. But you can learn so much more by studying some of the thousands of other galaxies in the sky, comparing and contrasting.

And of course, they teach us about our own galaxy, the Milky Way. After all, we live in its disk, so we see it edge on as well, even as we’re embedded in it. That makes it both the easiest and hardest galaxy to study; we can see it up close, but it’s maddeningly difficult to understand it as a whole. By studying other galaxies, separated from us by such unimaginable gulfs, we wind up getting a better grasp of, quite literally, where we live.

Categories: Astronomy Headlines

Healthy Google

Wed, 03/04/2015 - 06:42

Sometimes, it’s the little things.

I got an email the other day from someone who works with Google, telling me some cool news: They’ve updated their search results about health conditions. They now provide information that’s curated and vetted by doctors, including the Mayo Clinic!

That’s fantastic. So, for example, when you Google “measles,” the first couple of results are (as usual) news items, then links to the Centers for Disease Control and Prevention, the Mayo Clinic, and Wikipedia. I'll note that when I dug down a few pages in the results list, there still wasn't a single anti-vax site to be seen. Nice.

Another good part is that off to the right there's added information called a "Knowledge Graph" by Google (I took a screengrab, shown above). You can get more about symptoms and treatments, and under a drawing of someone with measles is this wonderful line:

A viral infection that’s serious for small children but is easily preventable by a vaccine.

Emphasis mine. That’s great. Little tidbits like that used casually—especially by Google—can go a long way toward marginalizing views that damn well ought to be marginalized. On the Google blog (linked above), they say that 1 in 20 searches are for health issues, so this update by them is hopefully going to have a very long reach.

I’ll note that Google contacted me because they saw my article about Kristen Bell advocating for vaccination. That too makes me happy. As you can imagine, the comments I get whenever I post about vaccines (in the blog comments as well as on Twitter and Facebook) are not always reality-based. It’s really great to know that Google is on the side of science. That’s not a surprise, but it’s still nice to see them doing their part. They obviously have a vast amount of leverage, and they’re using their powers here for good.

Categories: Astronomy Headlines

Rosetta Sees Its Shadow on a Comet

Tue, 03/03/2015 - 09:00

I suppose, if you want to be traditional about it, Valentine’s Day is a good time to get as close as you can to the one you love. That may be why the Rosetta space probe dipped to a mere 6 kilometers from the surface of the comet 67P/Churyumov-Gerasimenko on Feb. 14, 2015.

When it did, it saw something remarkable: Its own shadow on the surface of the comet!

I guess that means six more weeks of winter for 67/P. Of course, when your temperature is -70 C, it’s always winter.

A few weeks ago, Rosetta began a series of maneuvers that would take it very close to the comet’s surface, as well as several swings that would take it much farther away. The idea is to sample the environment around the comet in different places to see how things change.

At one point in the low pass, the Sun was directly behind Rosetta, so its shadow was cast on the surface. The spacecraft itself is a boxy shape roughly two meters on a side but has solar panels that extend 16 meters across, which is why the shadow is rectangular. It’s fuzzy because the Sun isn’t a point source—if you were on the comet looking up at Rosetta, it would only be blocking part of the Sun, so the shadow isn’t as deep where the Sun isn’t completely blocked. The same thing happens with eclipses here on Earth.

You can also see a brighter halo around the shadow. That’s called the opposition effect (or opposition surge or—my favorite—heiligenschein). Think of it this way: When the Sun is off to the side, you can see objects and their shadows. But if the Sun is directly behind you when you look at the ground, the shadow of, say, a rock falls behind it, and you can’t see it. On average the scene in that direction looks brighter.

Also, there’s a peculiar property of small grains that they can preferentially scatter light back in the direction it came. If the Sun is directly behind you, that means the light gets sent back at your eyes, making the ground look brighter. Look at dewy grass in the early morning (or dust in a baseball diamond, or similar areas covered in fine particles) and you’ll see a bright halo around your head. That’s heiligenschein.

The brightness of the halo depends a bit on the size of the particles doing the scattering, and that can be used to figure out the sizes of particles on the comet’s surface. So this picture of Rosetta’s shadow is more than just cool: It’s science.

That makes it extra cool.

And the detail! The image is a remarkable 228 meters on a side, the size of a big (American) football stadium. Think of those aerial shots you see during a game, and how you can see people sitting in their seats: That’s about the same scale as this shot. The resolution in the raw data is a stunning 11 cm per pixel. That’s the width of my hand (including my thumb). Wow.

And this mission is still in the early stages. Rosetta will follow 67/P for many more months to come, studying the comet as it nears the Sun. As it does, water ice mixed in with dust on the surface will turn even more vigorously into gas, and the comet will become more active. We’ve never been so close to a comet for so long as it does this. What amazing things will we see in the coming months?

Categories: Astronomy Headlines

The World, Ceres

Tue, 03/03/2015 - 04:30

On March 6, the Dawn spacecraft will ease into orbit around the largest asteroid in the main belt: Ceres.

As it approached Ceres on Feb. 19, Dawn took a series of images creating this amazing animation:

Although the resolution is still a bit low—this was taken from about 46,000 kilometers away, with a resolution of about 4 km/pixel—there are some interesting things you can see. For example, the mysterious pair of bright spots stays very bright even as they rotate into darkness, finally fading once the Sun fully sets for them.

That’s quite different behavior from another bright spot. Watch the animation: When the bright pair crosses over into darkness, turn your attention to the left side of Ceres. The next bright area comes into view after a moment, and as it rotates to the right, you can see it fade quite steadily, resolving into a crater with a bright but indistinct spot in it. For many features on airless worlds (and some with air, too) how bright a feature looks depends on the angle of sunlight hitting it. That bright region fades as it spins to the east and the Sun sets for it, but the very bright spots don’t.

That’s a clue about what they are. But we still don’t know! As Dawn gets closer, and the images get better, scientists will be paying attention to details like that so they can figure out just what they heck we’re seeing.

Another really interesting feature is an as-yet unnamed basin about 300 kilometers across (seen in the image above to the lower right); to give you a sense of scale, that basin would just fit in between Washington, D.C., and New York City. As I pointed out in an earlier post, it’s very flat given its width; I’d naively think it should be deeper. After the impact the floor may have filled in with water ice (Ceres has a lot of ice; it’s cold out there past Mars), or there may have been other forces at work. The edges of the crater don’t look round, either; it looks more like a rounded pentagon. That sometimes happens when a crater’s edge falls near cracks in the surface or the explosion shock wave hits material that’s a different strength. It could also simply be an illusion, caused by subsequent impacts marring the nice circular outline and fooling our eyes. Or it could be something else entirely; I’m guessing. Hopefully we’ll find out more in the coming months.

Excluding some fuzzy Hubble images, Ceres has been little more than a dot in our telescopes for centuries. Dawn hasn’t even gotten there yet and we’re already learning a huge amount about it … and getting even more questions. Of course, that’s why science is so much fun!

And a note: Some people call Ceres a dwarf planet, others a big asteroid. To be honest, I find that all a big distraction from the main point: Ceres is a world, a fantastic and fascinating place worthy of our attention and exploration. Dawn isn’t even really there yet and look what we’ve seen so far!

Categories: Astronomy Headlines

Waterspout Scares Beachgoers in Brazil

Mon, 03/02/2015 - 13:40

File this under terrifying but not as bad as it looks: Around 1 p.m. local time on March 1, a waterspout formed off the coast of a beach in Recife, Brazil. Of course everyone watched it, but then things got substantially more chaotic as the waterspout headed for the beach, scaring everyone and getting them to scatter.

Lots of video is popping up. Here’s one that shows the waterspout hitting the beach:

As you can see, it sends palm fronds and sand flying but doesn’t do a lot of damage (no injuries were reported). Waterspouts look like tornadoes, and they’re similar, but usually far weaker. Tornadoes form as air in a supercell starts to rotate, forming a localized and intense vortex that moves down from the cloud. Waterspouts like this one form more like dust devils, where a horizontal flow of air gets lifted up and maintains its rotation. Wind speeds in these so-called fair weather waterspouts—ones that form in calm weather, even if a dark storm cloud is nearby—top out at about 20 meters per second, but a tornado can easily have winds three times that speed.

Video taken from a different vantage point shows the spout while it’s still out off the coast, and you can see why people were freaked out; it does look like a tornado:

Amazing. The spout dies quickly once it’s over land; it probably couldn’t sustain the flow of warm air inward needed to maintain the spin.

While they’re weaker and tend not to do much damage, as you can see, you don’t want to screw around with them; the wind speeds are high enough to knock you down and carry debris. And some waterspouts do in fact form like tornadoes and can be much more severe. I’m glad no one was hurt here! And while the video is amazing, listen: If you see a waterspout heading toward you, it’s probably not the best idea to stop and take video. People will always take risks in weird weather situations, but I wouldn’t recommend it.

And if you see a fire tornado or an ash devil? Run.

Tip o' the beach umbrella to Clovis Tanganelli.

Categories: Astronomy Headlines

Crash Course Astronomy Episode 7: Gravity

Mon, 03/02/2015 - 08:30

I was traveling last week and couldn’t put up a post about Crash Course Astronomy when it came out. So, belatedly, here is Episode 7: Gravity!

Writing these episodes can be a tightrope walk. Gravity is an interesting topic; since we’re still early in the series, I wanted to go over the aspects of gravity we’ll need to talk about planets and moons, asteroids and comets. That means discussing it as a force, how it makes things move, how orbits work, and the difference between mass and weight. That also means not getting into things like how gravity curves space, and why massless photons are still affected by gravity. I mention it but don’t go into details. Think of it as a teaser for a later episode.

I wrestled over discussing how gravity is a force that accelerates things. This is part of Newton’s Second Law of Motion: A force acting on a mass will accelerate it.* The gravity of the Earth is independent of the mass it’s working on; it’s a property of the Earth itself. If you drop two objects of different weights, they’ll fall at the same rate (ignoring air resistance). My friend Brian Cox demonstrated that quite ably.

The objects will accelerate, which means that the longer they fall, the faster they’ll go. That acceleration is a property of Earth’s gravity, and will be the same for any object. Drop a ball near the ground, and it will accelerate at a rate of about 9.8 meters per second for every second it falls. After one second it’s moving at 9.8 m/s. After two seconds it falls at 19.6 m/s, and so on.

But the force it feels is different than a ball that has a different mass. That’s the weird part that can be confusing. Gravity accelerates everything the same, but if you have more mass you feel more force. When it comes to gravity, we call that force weight. Because the force is bigger we think a more massive ball will fall faster, but it doesn’t because the acceleration is the same as it is for a less massive ball.

But if you want to stop a heavier ball, you’ll have to apply more force than you would on a lighter ball. When the heavier ball hits the ground, it hits harder than the lighter one, even though they’ll impact at the same speed.

Now, did you notice the verbal switcheroo I just pulled? I talked about the more and less massive balls in one paragraph, then called them heavier and lighter in the next. That’s sloppy (though I did it on purpose to prove a point)! In deep space, with no (or negligible) forces acting on them, they both weigh the same: nothing. But their masses are different. Wheee!

If you think you get this now, yay! Good. But here’s a test: What weighs more: a 5 pound helium balloon, or a 5 pound block of cheese? The answer may seem obvious, but explaining it isn’t all that easy.

Maybe I’ll need to make a bonus video with that. I’ll need a big balloon. I wonder if I can get George Clooney and Sandra Bullock to guest star?

*Actually an unbalanced force; if you have another equal but oppositely directed force acting on it, the object won’t accelerate. If it’s moving it’ll still move, but if it’s just sitting there it won’t start to move. See why you need to simplify sometimes? You just need to be careful that you don’t oversimplify and make things worse. That’s another reason writing these episodes can be tricky.

Categories: Astronomy Headlines

The Week in Political Buffoonery

Mon, 03/02/2015 - 04:15

As someone who understands science and math, I know that when you look into a particular population looking for instances of a particular behavior, sometimes those behaviors will cluster in time. You might go a few weeks with very few instances, and then suddenly see a big clump of them happening at the same time.

Of course, when we’re talking anti-science buffoonery in politics, there is a vast, vast sample size. The statistics are pretty good.

Still, last week there were a large number of forehead-smackingly nonsensical ridiculosities. Out of them all, here are three guaranteed to put a dent in your desk where your head slams into it.

1) James Inhofe Disproves Global Warming Because Snow

James “Global warming is a hoax” Inhofe (R-Oklahoma) has never met an argument against climate change too silly and obviously wrong not to repeat. Last week, he actually stood on the floor of the United States Senate, and talking about global warming, he—and I can’t believe I’m typing this—pulled a snowball out of a plastic bag and said,

I ask the chair, you know what this is? It’s a snowball, just from outside here. So it’s very, very cold out. Very unseasonal.

Yes, Senator Inhofe, it snows, because it’s winter. The planet is warming up, but it still gets cold in the winter (at least it does for now). If your average low temperature in February is, say -10° Celsius, then it can warm up a few degrees and still be below the freezing point of water. That’s grade school math.

Clearly, Inhofe is an Axial Tilt Denier, too. I wonder how he’d feel knowing that he has a lot in common with a Saudi cleric.

As Stephen Colbert has said, the idea that winter disproves global warming is like nighttime disproving the existence of the Sun. If you want details, Jon Stewart did a great job slam-dunking the it’s-cold-outside-therefore-no-global-warming dumbosity.

Snark aside, Inhofe’s head is quite firmly in the sand, and he’s an embarrassment to the Senate.  I hope this is his “Michael Dukakis in a tank” moment. Thank heavens another Senate member, the wonderful Sheldon Whitehouse (D-Rhode Island), took him to task for this.

2) House Science Committee Member Doesn’t Vaccinate

Speaking of dangerous rhetoric, on the House side, Rep. Barry Loudermilk (R-Georgia) took a moment in a public town-hall meeting to let everyone know he didn’t vaccinate his kids:

Great, huh? He tried to follow up later saying he’s not against inoculation, but it’s clear he doesn’t understand the issue (and by the way Jenny McCarthy says she’s not anti-vax, either). And we know Tea Partiers tend to the anti-vax as well, though it’s usually about being anti-government, not anti-science per se.

Did I mention Rep. Loudermilk is on the House Science, Space and Technology Committee? It may be past time to change its name.

And Rep. Loudermilk, when a GOP strategist tells you to resign over something ridiculous that you’ve said, you really, really need to rethink your position.

3) A Load of Taurus

American politicians don’t hold the monopoly on anti-science nonsense. Unhappily, facing away from reality knows no country’s borders. Case in point: Tory MP David Tredinnick thinks that a lot of the UK’s health problems could be helped by turning to astrology.

Just go to that link and see if you can count how many logical fallacies he relies on to back up this sentiment. Have a calculator handy. In the meantime, I’ll just leave this here.

So yeah, I’m being a bit snarky, but remember, these are critical topics—the environment, public health, and the health of science itself. If these politicians are willing to dump evidence-based reasoning by the side of the road, then what else are they willing to do? And they make our laws.

It’s time to dump them. If your representatives don’t believe in reality, then next election time it’s your responsibility to show it to them.

Categories: Astronomy Headlines

Me vs Hank Green: SciShow Quiz Show

Sun, 03/01/2015 - 04:30

Part of the vast Hank and John Green video empire includes SciShow, a YouTube channel that has a variety of different science shows on it, like SciShow Dose (quick videos on interesting topics), News, Infusion (longer videos, like the vaccine one I posted about recently), and many more.

They also have Quiz Show, where two sciencey-type people go head-to-head in a snarky contest to see who knows more science, but which in reality just shows who can guess the answer better than the other.

When I was up at HQ last time filming some episodes of Crash Course Astronomy they asked if I wanted to be on Quiz Show, and never one to give up an opportunity to make a fool of myself on camera, I said sure. So they pitted me against the man himself, Hank, in a battle of brains. Who will win? Find out for yourself:

So, congrats Ian! I hope you enjoy your swag. And yes, I was very pleased with myself for deducing the answer to the second question, getting it right for the right reason. SCIENCE!

Categories: Astronomy Headlines

Ticket to Space

Sat, 02/28/2015 - 04:30

My friend Dan Durda is many things: an astronomer, a planetary scientist, an artist, a pilot.

He’s also an astronaut. Or he will be, very soon.

He works at Southwest Research Institute here in Boulder, Colorado, which is a company that does a lot of work in space; the New Horizons Pluto probe instruments were developed there, for example, and the principal investigator, Alan Stern, is there. Dan’s very interested in the behavior and structure of asteroids, which is difficult to study here on Earth.

So he and his fellow scientists at SwRI got an idea: Go into space.

We’re at the doorstep of cheaper, more reliable access to space. Ticket prices are within reach of wealthy individuals and, perhaps more importantly, companies that do science. A lot of Dan’s experiments can be done easily in the few minutes of weightlessness these suborbital flights provide.

But why not get all this from Dan himself? He recently gave a TEDxBoulder talk about this, and it’s really good.

What he said is true: We’re just starting off doing this work, and we don’t know where it will lead. There have been setbacks, for sure; the loss of the Virgin Galactic vehicle and its pilot last year, and the explosion of the Antares rocket upon liftoff.

As I have written many times before, while tragic, these sorts of losses are inevitable. They are the price we pay for pushing boundaries, and you’ll find most astronauts understand these risks. To use an analogy Dan made in the video, where would be now if airplane crashes grounded the airline industry in the early 20th century?

We’ll continue on, pushing our way into space. Again, as Dan points out, we cannot know where this will lead … except up. And that’s a direction I think we should go.

Categories: Astronomy Headlines

Psychedelic Crab

Fri, 02/27/2015 - 04:30

The benefits of cleaning out your inbox: I somehow completely missed this spectacular image when it came out a while back, but now that I’ve found it I can share it!

Ye. Gads.

That’s the Crab Nebula, one of the most well-studied and famous objects on all the sky. It the expanding gas cloud left over from a titanic supernova explosion, in this case the death of a very massive star. The light from this explosion reached Earth in 1054, and in the subsequent millennium the debris has reached a size of well over 10 light years.

That’s 100 trillion kilometers, just so’s you know.

This image combines observations from Hubble taken in visible light with far-infrared observations using the Herschel observatory. Supernovae explosions combine huge temperatures with unbelievable pressures, enough that elements in the star undergo what’s called explosive nucleosynthesis: The blast actually fuses them together to make heavier elements. Cosmic alchemy!

Oxygen and sulfur in the debris glow fiercely in visible light. Hubble used three filters to pick those elements out, and those images were combined in the above photo and displayed as blue. Herschel is sensitive to dust: complex carbon-based molecules also created by the shock wave from the explosion. Those observations are colored red here. Where you see pinkish is where the nebula appears bright to both observatories.

I was also interested to see that Herschel had also taken spectra of the nebula, separating the light out into different wavelengths. When you do that you can measure various properties of the object observed, including its chemical composition. They found strong evidence in the spectra pointing at the presence of something truly weird: Argon hydride.

Argon is a noble gas. The atoms of argon are configured in a way that it’s (in general) chemically inert; it won’t combine with other elements like carbon or oxygen do. Seeing it forming molecules is pretty strange. In this case, the argon in the nebula is zapped by fierce ultraviolet light from the central neutron star, the ultra-dense remnant of the core of the star that exploded. This rips electrons off the argon, making it easier for it to combine with other material in the gas.

Not only that, but elements come in different flavors called isotopes. They have the same chemical properties, but have fewer or more neutrons in their nucleus, changing the mass of the atom. This also changes the spectral properties of the light emitted. On Earth, the most common flavor of argon is argon-40, with 18 protons and 22 neutrons in its nucleus (made when radioactive potassium decays).

But the astronomers found argon-36 in the nebula, which only has 18 neutrons. That isotope is more common in space, and is created in the wave of supernova-driven nucleosynthesis. It makes sense they saw it in the Crab, even if it was a surprise it was in a molecular form.

Given that the Crab is big, nearby, bright, and so thoroughly scrutinized that I think it’s pretty cool that it still has a secret or two up its carapace. No matter how familiar we are with something, there is always more to discover.

Categories: Astronomy Headlines

Kepler-432b: A Doomed Planet Orbiting a Doomed Star

Thu, 02/26/2015 - 07:45

Two independent teams of astronomers have just announced the discovery of an unusual planet with a grim future: Kepler-432b.

The planet orbits a star nearly 3,000 light-years away and was discovered using the Kepler observatory, which looks for telltale dips in star light as a planet orbits a star; if the planet’s orbit is seen edge-on from Earth, then once per orbit it blocks a small fraction of the star when it passes directly between the star and Earth.

Measuring the timing of the dip (and knowing some of the properties of the star) yields a lot of information about the planet, including its size, and the size and shape of its orbit. They also took spectra of the star, breaking its light up into thousands of individual colors, which yields one more crucial piece of information: the mass of the planet. The planet and star orbit a common center of gravity, and as the star moves in its orbit its spectrum changes due to the Doppler shift. This effect is pretty dang small, but measurable using precision instruments.

The results are pretty cool: The planet Kepler-432b is roughly five times more massive than Jupiter, but only about 1.1 times as wide. This makes it pretty dense, about as dense as Earth! Gas giants have a weird property that as they get more massive their size doesn’t increase much—instead, the pressure inside them increases, and their density goes way up. Jupiter is right at about the lower limit where that happens, so planets can be much beefier than Jupiter but not much bigger.

But what makes this system special is the star itself. It’s a little more massive than the Sun, but it’s what we call a red giant: A star that is starting to die.

At some point in the past, the star Kepler-432 ran out of hydrogen fuel in its core. The core of the star is shrinking and heating up, dumping all that heat into its outer layers. What happens to a gas when you heat it up? It expands. And so Kepler-432 has swollen up to a size about four times wider than our Sun. As it got bigger its surface area increased, too, and so, weirdly, the amount of energy coming through its surface per square centimeter has actually dropped, lowering its temperature. Cooler stars are red, so Kepler-432 is a red giant.

It will continue to grow as it ages, swelling to a much larger size than it is now. Much larger. Will it engulf the planet?

It may not grow enough to swallow the planet directly. However, as it gets bigger, it interacts with the planet via tides, and (through a complicated series of steps) will actually drop the planet closer in to the star.

It looks like this one-two punch is enough to doom the planet. The star will grow larger, the planet’s orbit will shrink, and then … doom. The planet will fall into the star, where it will plunge deeper and deeper, until it evaporates completely.

But don’t despair too much. As the planet falls inside the star, it takes a while to disintegrate. It orbits much faster than the star spins, so it may churn up the insides of the star like a whisk in a mixing bowl of batter. The star’s rotation will increase. As the star continues to age, it will fling off its outer layers, exposing the hot core at its center. This very dense, very hot object, now called a white dwarf, will blast ultraviolet light into space, illuminating and exciting the gas it ejected, causing it to glow. Because the star was spinning, this gas can take on fantastic shapes, including double-lobed patterns reminiscent of butterfly wings.

Scientifically, this system is fascinating; we don’t have too many examples of giant planets orbiting red giant stars (which may be in part due to the fact that they tend to fall into their stars!), so every one we find is important. The planet orbits the star on a long ellipse, too, which is unusual and difficult to explain. There are many mysteries to plumb here.

And metaphorically, well, this transformation is almost too on-the-nose: Like a caterpillar, the planet and star will transform into something magnificent, literally a butterfly shape. And it will glow fiercely like that for centuries, its beauty visible easily from telescopes even thousands of light years away.

The Universe is all about change, birth, destruction … and given that, perhaps Kepler-432b’s eventual fate isn’t such a bad one.

Postscript: You can read the papers published by the two teams who studied this planet: Ciceri et al., and Ortiz et al. Their results match pretty well, though, interestingly, Ciceri et al. find no evidence for a second planet orbiting the star, while Ortiz et al. do. Also, Ciceri et al. conclude the planet won’t be engulfed. I don’t think they included the work showing the planet’s orbital radius will shrink, though, which was considered by Ortiz et al., so I tend to agree with Ortiz’s team. The planet is doomed.

Categories: Astronomy Headlines

Ceres Is Getting Weirder

Thu, 02/26/2015 - 04:00

Dawn approaches Ceres.

The spacecraft Dawn, that is, and the asteroid Ceres, the largest of the rocks orbiting the Sun between Mars and Jupiter. Dawn has been headed slowly toward Ceres for many months now, and only recently has its target been big enough to see as more than a dot. 

On Feb. 19, 2015, Dawn took the image of Ceres above from a distance of 46,000 km (29,000 miles; roughly an eighth the distance of the Moon from the Earth). Earlier pictures already revealed a bright spot on the surface, and now the resolution is good enough to see it’s not one spot, but two. Like a distant car on the highway getting near, and seeing its headlights split from one bright glare to two, Dawn’s proximity to Ceres has allowed us to see the shiny spot is not alone. 

It’s still too early to say what we’re seeing here. Ceres has a lot of water ice inside it, and it seems likely these spots are related to that. You can also see they’re located in a crater—which isn’t necessarily remarkable; as you can see the whole surface of Ceres is saturated with them. My initial thought was that an impact had revealed ice underneath the surface, digging it up. We see that in some craters on Mars, for example.

But now I wonder. It’s possible that we’re seeing cryovolcanism: literally, ice volcanoes. But it’s hard to understand what would drive that. Ceres is too small to have tectonics, and has no moon that might generate tides to warm the interior. 

At the moment, it’s a mystery. And that’s good! We've never seen Ceres in this detail before, so everything we learn about it will be new.

For example, look at the large craters on it. They look to me to be flatter than craters that size would be on other worlds. I suspect we’re seeing either a softer surface, or that ancient, big impacts melted ice under the craters which flooded the floors. We see similar things on the Moon, but in that case it was molten rock, not water, that filled the floors. 

But I’m speculating, based on what we see so far. And these are still relatively low resolution images; compare them to what we saw when Dawn orbited Vesta, its first asteroid target, to get a taste of what’s coming. Dawn will enter orbit around Ceres on March 6, and will continue to orbit the asteroid for well over a year. What mysteries will it unveil that we haven’t even guessed at yet? 

Categories: Astronomy Headlines

Tempest Vermilion

Wed, 02/25/2015 - 08:45

Gavin Heffernan is a photographer who travels to difficult-to-reach locations and shoots simply tremendous time-lapse videos of the landscape and night sky he sees there.

He just sent me a note that he’s created another video, and, well, holy wow. It’s another stunner: “Tempest Vermilion,” shot at the Vermilion Cliffs National Monument in Arizona.

You know the drill: Make it full screen, set it to high-def, crank up the volume, and let your eyes and brain soak it up.

Photographic stills from the shoot are on Flickr.

This is the second part of a trilogy of videos Heffernan has created for BBC 2; the first, called “Wavelight,” is online as well. He and his collaborator, Harun Mehmedinovic, are also making a video about the effects of light pollution. Called “Skyglow,” it’ll be on Kickstarter in early April. Stay tuned for that.

In the meantime, take a look at these other amazing videos by Heffernan:

Time-Lapse: Kings Canyon
Time-Lapse: YIKÁÍSDÁHÁ
Death Valley DreamLapse
Predators and Prey, Dragons and Dark Skies

Categories: Astronomy Headlines

A Supermassive Black Hole’s Fiery and Furious Wind

Wed, 02/25/2015 - 04:30

When you think of black holes, you probably think they are chaotic destroyers of all; wandering through space devouring everything in their path, and once something gets too close, it’s gone forever.

That’s a little unfair. Actually, a lot unfair. They only eat stuff that’s nearby, for one thing. And for another, they’re sloppy eaters. Not everything falls straight down their gullet; a lot of it can swirl around the black hole in what’s called an accretion disk. Material in that disk can be heated to terrifyingly high temperatures, millions of degrees, causing it to glow fiercely bright. It can blast out X-rays, and even create an intensely strong wind of material that flows away from the black hole.

We also know that every big galaxy we look at has a supermassive black hole in its very center. If that black hole has gas and matter falling into it, the accretion disk can be huge and ridiculously, soul-crushingly bright. The luminosity of such an object can easily outshine the hundreds of billions of stars in the host galaxy, and make the black hole visible clear across the Universe.

This sets up an interesting problem. When you have a monster in the middle like that, how does it affect the rest of the galaxy? A curious fact was discovered many years ago; the mass of the black hole in a galaxy seems to correlate with how the stars in the galaxy orbit. You might think “duh” to that, but hang on. Even though a black hole can have a mass of a billion times the Sun, that’s a teeny tiny fraction of the mass of a galaxy with a few hundred billion stars in it.

Somehow, the black hole is affecting the galaxy around it on a huge scale. How?

The obvious way is through this wind, this cosmic hurricane of particles blasting outward from it at high fractions of the speed of light. Studying that wind is maddeningly difficult, though. For example, when we look right at the center of the galaxy, all we can see is the extremely narrow slice of gas between us and the black hole. That gas absorbs the light coming from the accretion disk, blocking it. As it happens, different kinds of atoms block different colors of light. One type of iron, for example, that has a lot of its electrons ripped away from the intense energy blasting away nearby, is really good at absorbing a very specific wavelength of X-rays.

That can tell you something about the gas, like how hot it is, and how fast the gas is moving away from the black hole. But what it doesn’t tell you is the overall shape of the wind. Is it blowing out spherically, like an expanding balloon, or is it focused into narrow beams?

Lots of black holes have those beams screaming away from them. We know this because we can see them. But not every black hole has them. So how can you figure out the shape of the wind?

Some astronomers have just announced they found a way. The black hole they observed is a billion-solar-mass beast in the center of the galaxy PDS 456, which is about 2 billion light-years away. It’s fairly well studied, and is a good example of a typical “active galaxy,” one with an actively feeding black hole in its core.

They observed it using two different observatories: XMM-Newton and NuSTAR. Both can sort incoming X-rays into their individual energies (think of that like color in light we see). XMM-Newton could see the gas blocking the black hole directly, but can’t detect any gas anywhere else. NuSTAR, however, is able to see the kind of X-rays that would be coming from gas surrounding the black hole … and it did. Looking at the spectrum of the X-rays, it found the unmistakable signature of gas expanding outward in a sphere (if you want technical stuff, it saw a classic P-Cygni profile).

This is a big deal. The geometry of the expanding wind can tell us its total energy. Think of it this way: Imagine you have a 1-watt light bulb. It looks pretty dim, because it’s sending light out in all directions. Only a little bit of the light is heading into your eye. But if I have a flashlight, it focuses the energy emitted, so it can gather up all the light being wasted in other directions and beam it toward you. The bulb in a flashlight can be a lot dimmer, but still look brighter to you because of that.

And that’s the basis of these new observations. They saw that the wind from the black hole is expanding in all directions, which means the astronomers could determine the overall physical nature of the wind. It turns out the black hole is blasting a wind that totals 10 times the Sun’s mass every year—and mind you, that vast amount of stuff is screaming out at tens of thousands of kilometers per second. If I’ve done my math right (and I have; I checked), that means the mechanical energy in that wind is a staggering 10 trillion times the total energy the Sun emits every second.

Ten trillion.

And that wind is blowing outward in all directions, so it can easily affect the gas around it, even thousands of light-years away. This in turn would affect how stars form in a galaxy, and explain the relationship we see between the black hole and the stars in the galaxy around it.

And here’s the really cool thing: We think those big black holes form at the same time as the galaxy itself. As the zillions of tons of gas swirl around in the proto-galaxy, assembling itself into stars, some of it is falling into the nascent black hole in the center of that maelstrom. It forms a disk around the black hole, heats up, and starts to blast out a wind. This wind slams into the gas around it, all around it, blowing it hither and yon.

When the galaxy finally coalesces as a massive island universe of billions of stars, the motions of the stars themselves still have the fingerprint of the black hole’s wind imprinted on them, even billions of years later. And that wind may have helped trigger more stars being born as it rams into and compresses the gas around it, just as it can also shut down star formation by blowing that gas away.

Our galaxy, the Milky Way, has such a black hole in the middle. It’s not a big one as they go, a mere 4 million times the mass of the Sun. But 10 billion years ago, when our galaxy was forming, it may have been active, and may have affected the young galaxy around it as well.

When you go outside at night and look at the stars, think on that. If you can see Sagittarius, you’re looking toward the center of our galaxy, where that monster dwells. It’s surrounded by billions of stars, so distant from us their light merges into a soft glow. But they’re there, those myriad stars, and their motions, their formation, even their existence itself may have been profoundly influenced by a black hole that we didn’t even know existed until a few decades ago.

Ah, science. It allows us to wonder about the inner workings of the Universe we live in, and then shows us how the pieces fit together. If there is a grander, more exhilarating adventure than that, I don’t know what it is.

Categories: Astronomy Headlines

Why Do Some People Refuse to Get Vaccines?

Tue, 02/24/2015 - 04:30

There’s been a lot of discussion in the media (both mainstream as well as social) about vaccinations, spurred because of the current measles outbreak in the U.S. I’m unhappy about the cause, of course, but I welcome the discussion. I’m just sorry it took an outbreak from Disneyland to get this conversation rolling.

A lot of people are blaming anti-vaxxers for the outbreak, but the truth is more complicated than that. Certainly Jenny McCarthy, Andrew Wakefield, and the organized groups spreading dangerous misinformation about vaccines have their share of it, but their influence isn’t almighty. There’s more to this story. 

That’s why I’m glad my friend Hank Green has made an episode of SciShow explaining why people choose not to vaccinate.

Hank’s overview is pretty good, and very well laid out! But I want to add a few things.

One is that this is not just a hippie, liberal thing. Very conservative people, including libertarians, don’t want the government telling them what to do, so state-required vaccinations for children to allow them in schools is anathema to them. I’m not saying they’re right—in fact, they’re very, very wrong—just that this is what they think. Anti-vaccination sentiment is well distributed throughout the political spectrum.

Another is that overall in the U.S., vaccination rates haven’t fallen in recent times. But that casts a mighty wide net. If, instead, you look on smaller scales, you see pockets of low vaccination, regions where rates have dropped dramatically. Sure, some are liberal bastions like Northern California, but other places are affected for other reasons, like the Texas town influenced by a megachurch.

And, as always, I want to point out that I understand how parents feel here. I have a daughter myself, and my wife’s and my concerns for her health were and are strong. So I want to distinguish between parents out there trying to figure this all out, and the people who are actively and vocally trying to confuse them over this issue.

I know how important vaccines are, and my entire family is up-to-date with their vaccinations. I’m walking the walk

Hank’s audience for SciShow tends to be younger folks, and I hope they take this lesson home (literally as well as figuratively). This issue of bias and evidence goes well beyond vaccinations, into the very trust we have of science itself. That’s something I’d love for younger folks to understand. Science is pretty cool, and the most important tool humans have to understand everything around us.

It also saves lives.

Addendum: Germany is facing a large-scale outbreak of measles as well, with nearly 600 cases since late last year (the population of Germany is one-fourth that of the U.S.). One boy, an 18-month-old, recently died from complications due to measles. My heart aches over this, which is why I write so frequently about vaccination. My thanks to Mat Johnson for alerting me to this.

Categories: Astronomy Headlines

Mooning Pluto

Mon, 02/23/2015 - 04:30

Pluto is an interesting little world. Smaller than our Moon, it still boasts no fewer than five moons discovered so far. The first, Charon, was discovered in 1978, but the second through fifth were found just a few years ago using Hubble data.

How many does Pluto have? It’s not known, because smaller, fainter moons may yet be undiscovered. But as the New Horizons probe nears Pluto, we may find more.

Charon is big and relatively bright, and has been seen in New Horizons images since 2013. But now two of the smaller moons, Nix and Hydra, have been spotted as well!

The animation on the left shows Pluto heavily overexposed (the bright tail off to the right is called blooming, and it’s an artifact of some digital detectors), with stars in the background. The moons have boxes around them to make them easier to spot. The animation on the right has the stars subtracted off, making it easier to see the moons’ orbital motions around their parent body. To give you a sense of scale, Nix and Hydra orbit about 50,000 and 65,000 km out from Pluto. The moon’s physical sizes are unknown, though less than 100 km across. They’re unresolved in these images, and in the Hubble images as well. When New Horizons gets closer it will certainly give us a far better idea about these little guys.

Each frame of each animation is a total of a 50 second exposure, which is pretty impressive. New Horizons is moving pretty fast, about 14 km/sec, so it needs to take short exposures as it flies through the Pluto system or else there will be motion blur.

These images are mere tastes of what’s to come. In the months ahead we’ll see Pluto resolved, surface features revealing themselves, and more detail on these moons as well. Perhaps the probe will discover more moons circling Pluto, too.

Hopefully it will shed light on how the moons formed; one current theory is that Pluto and Charon formed at the same time, out of the material that formed all the icy bodies past Neptune. Then, later, an impact on Pluto blasted chunks into space, which formed the other moons. Pluto doesn’t have a lot of gravity, but it also lacks nearby neighbors, so it can hold on to several moons without losing them due to perturbations from other massive bodies. We know many asteroids and other big icy objects past Neptune have moons, so seeing these close up may be able to help us understand how they came to be in the first place.

Categories: Astronomy Headlines

Conspiracy Revealed: The Simpsons Has Been Lying to You

Sun, 02/22/2015 - 04:30

I’ve been a fan of The Simpsons for a long time. Obviously. So when I heard that SpaceX’s head guy Elon Musk was guest-starring on the show, I hoped it would be a good episode. And it was! As I watched I marveled at how funny the show was even after all these decades, and laughed quite a bit as the story unfolded.

… until a scene came up that chilled me to the bone. I was so shocked that I had to rewind and watch it again, then freeze frame it to make sure I wasn’t hallucinating.

This is the moment that changed everything for me. The frozen moment of time when I realized that for 22 years, The Simpsons has been lying to us.

This shows Musk standing at the dining room window of the Simpson’s house, looking out and pontificating at the night sky as the family behind him eats dinner.

But look at the Moon. LOOK AT THE MOON!

It’s backwards. The scene is clearly at dinner, early evening, so that’s the setting crescent new Moon. But in the northern hemisphere, the tips of a waxing crescent Moon point to the left, away from the Sun. Here’s a photo I took myself in November 2013:

See? I took that picture shortly after sunset, around dinner time. It was new Moon, and the crescent's tips point to the left. But in that scene with Musk, they point to the right! How can that be?

There’s only one way. Springfield is not in the United States at all. It’s not even in our half of the world. Springfield is in the southern hemisphere!

I don’t even know how to react to this information. It’s as if… my whole world has been turned upside down.

Categories: Astronomy Headlines

Stars of Reality

Sat, 02/21/2015 - 04:30

Y’know, it’s easy to make fun of celebrities who endorse ridiculous nonsense. Certainly Jenny McCarthy has earned the wrath she’s received over vaccines, and Rob Schneider says things that make McCarthy look like an icon of reason. Even Bill Maher, praised on many topics by critical thinkers, says things about vaccinations that make me cringe.

But I think it’s just as important to praise celebrities when they do the right thing. I’m a big fan of Amanda Peete, who is an outspoken supporter of actual, true vaccine information, and of Sarah Michelle Gellar as well.

And now I can add to that list actress Kristen Bell. I’ve always liked her, but now I can add her to my cadre of celebrities I respect. Why? She said this:

When [my daughter] Lincoln was born, the whooping cough epidemic was growing, and before she was 2 months old, we simply said [to friends], 'You have to get a whooping cough vaccination if you are going to hold our baby.'

Nice! Simple, straightforward, and makes the message clear. And if that weren’t enough, bless her reality-based brain, she went on to say,

It's a very simple logic: I believe in trusting doctors, not know-it-alls.

Heh. A bit more snarky than I would’ve phrased it, but the sentiment is understandable. I always want to be clear that I distinguish carefully between parents who are being misled, and the ones who mislead them. When I use the word “anti-vaxxer”, overwhelmingly I mean the latter, especially those vocal few who willingly or otherwise grossly distort reality to fit their own views.

It’s easy to be confused by doubt-sowers, especially if it’s in a topic with which you’re not that familiar. And Google will fail you there; leading you many times to the very pages of the anti-vaxxers themselves, instead of more reliable sources (like the CDC,  Harpocrates Speaks, Voices for Vaccines, the Autism Science Foundation, and Every Child by Two). And a lot of those anti-vax groups produce dangerous information, ideas that are a clear threat to the public health.

So again, I will continue to praise people in the pubic eye who take a stand for reality. Good on you, Ms. Peet, Ms. Gellar, and now Ms. Bell. Count me as a fan.

Addendum: Parenting magazine has a list of other celebrities who support vaccination. 

Categories: Astronomy Headlines

Pluto, Unphased

Fri, 02/20/2015 - 09:36

On July 14, 2015, the New Horizons spacecraft will fly by Pluto, passing the surface by just a little over 12,000 kilometers.* This will be the first time in history we’ll have seen the little world and its moons close up, and I’ll be honest, the excitement is building.

A couple of weeks ago, the probe’s Long Range Reconnaissance Imager took a series of snapshots of Pluto and its big moon Charon, spanning about a week: the amount of time it takes the two to orbit each other. The images are amazing:

Note that both Pluto (the brighter one) and Charon (the dimmer one) are both moving. That’s because Charon has about 12 percent the mass of Pluto, which means that while Pluto’s gravity is pulling on it, Charon is pulling right back. So Charon makes a big circle around Pluto as it orbits, and Pluto makes a little one around Charon … or, to be technical, they both orbit their barycenter, their center of mass. I explain all that in an earlier post when this motion first became visible to New Horizons.

Note that the images here have been expanded a lot to make things easier to see; both objects look pixelated. When I first saw this animation, I was thrown for a moment: It looks like Pluto is half full, being lit more or less from the left. But I knew that couldn’t be right; it would mean New Horizons would have to be approaching Pluto from the side; with the Sun far off to the left in these images.

Pluto is 30 times farther from the Sun than Earth is, so I knew that the probe was heading toward Pluto with the Sun almost directly behind the spacecraft, not to the side. I figured I’d better see what’s what here, so the first thing I did was look up Pluto’s trajectory.

As you can see, I was right; New Horizons is heading almost directly away from the Sun. From its point of view, Pluto is nearly opposite the Sun in the sky, and so it sees a very nearly “full” Pluto, its face almost 100 percent illuminated. In fact, the probe won’t see an appreciable phase to Pluto until just hours before closest encounter, which occurs at 11:50 UTC on July 14.

So clearly, the fact that Pluto looks half-lit must be an illusion, just coincidence in this zoomed view. But just to be sure I dug a little deeper. Knowing Pluto’s size, the distance to it when the images were taken, and the resolution of LORRI, I calculate that Pluto is a mere two pixels across in the pictures! Clearly, it can’t be showing a half phase if it’s that tiny, so again it must just be that the random blobbiness of it when the image is expanded makes it look that way. Incidentally, it looks bigger than two pixels because of a quirk of optics; any very small source of light gets smeared out a bit due to diffraction.

When these pictures were taken, New Horizons was farther from Pluto than Earth is to the Sun. But it’s moving, screaming across space at 14 kilometers per second; assuming it takes you three minutes to read this entire post, New Horizons will have traveled 2,500 kilometers farther from Earth and closer to Pluto by the time you reach the end.

Pluto is only about 2,400 km across (smaller than our Moon), so it won’t look like much until just before the encounter. Roughly speaking, a bit more than a month out, in early June, it’ll be 10 pixels across. It’ll be 100 pixels across when New Horizons is four days away from closest encounter and about 5 million kilometers away, and will grow from there. Until then, we’ll just have to be happy with these blurry images.

But they won’t stay blurry for long. Soon, in just a few months now—after a voyage of more than nine years and 5 billion kilometers—New Horizons will finally show us Pluto’s face. 

Correction, Feb. 20, 2015: This post originally misstated that the closest encounter is on Feb. 14, 2015, but it's actually July 14. 

 
Categories: Astronomy Headlines

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