Bad Astronomy Blog
Last week, we put up Episode 30 of Crash Course Astronomy, and after every [episode modulo 10 = 0] episodes we post a blooper reel, outtakes from the last few episodes we’ve recorded.
So here you go, Outtakes No. 3, which is mostly me mispronouncing things and making faces.
And hey: At the end of the video above we make an announcement: We have a Crash Course Astronomy poster for sale! It was created by our animators, Thought Café, and I helped write and edit the captions for the drawings. It’s pretty cool. At 46 x 61 centimeters (fine, 18 x 24 inches for you imperial unit folks), it’ll look handsome and lovely on your wall, door, inside car windshield*, meat drawer†, and/or observatory dome.
*Don’t actually put it there.
†Not a euphemism.
I’ve been writing about what global warming means to our planet and to us for a long time now. A critical concern for this is the loss of land ice in Antarctica and Greenland, for many reasons. One is that it's a bellwether for our poles, a preview of what it means as we turn up the global thermostat. Another is that it contributes to sea level rise, which has been moving upward for quite some time now.
But land ice loss is perhaps most important as a political trigger; the sheer amount of land ice being lost every year is immediate, here, now. And the numbers are staggering: Using data from the GRACE satellites launched in 2002, scientists measured that the Antarctic ice sheet is losing 134 billion metric tons per year, and Greenland is losing 287 billion tons per year.
I’m an astronomer. I deal with numbers this large all the time. But internalizing them is another issue altogether; after a while they just become, well, numbers.
Perhaps a change in perspective is called for. Those rates quoted are horrific, but what do they mean for the total ice lost from those two regions?
Yesterday, NASA posted the graphs above on their climate change website, and that hammered home just what 420 billion tons of ice melting annually means when looking back into the recent past.
From 2002 to mid-November 2014 — less than 13 years — the combined land ice loss from Antarctica and Greenland is over five trillion tons.
Five. Trillion. Tons.
That’s beyond staggering; that’s almost incomprehensible. It’s a volume of about 5,700 cubic kilometers, a cube of ice nearly 18 kilometers — over 11 miles — on a side. Place that cube on the ground, and the top of it would be above 90 percent of the Earth’s atmosphere, reaching twice the height of Mt. Everest.
Five trillion tons. Remember that the next time some climate change denier starts spouting the usual nonsense about sea ice increasing. That claim is very close to a bald-faced lie. First, arctic sea ice is declining rapidly. Second, arctic sea ice loss is so huge that it easily overwhelms any temporary gains in Antarctic sea ice. And third, sea ice is very different than land ice. Land ice loss isn’t getting replaced anywhere near the rate it’s being lost. Once it slides into the sea, it’s gone.
Except it isn’t really. It’s gone as ice. It’s still there as fresh water, making sea levels rise and potentially altering the currents of warm and cold water that further regulate our climate.
Whenever I make a post like this, I get emails, tweets, and comments from people who deny global warming is happening, and they point to fatally flawed “evidence” — cherry picking data (like looking at small regions instead of global data), ignoring trends to look for small spikes in time, distracting people by using misleading examples of cooling or ice growth. It’s the same tired garbage all the time.
The reality is we’re warming up. The reality is we’re losing ice at both poles at tremendous rates. The reality is our climate is changing, our weather is changing, our lives are changing.
We need to recognize that, and we need our politicians to recognize that. The deniers rely on bad science and pathological interpretations. Despite recent baloney about it (is Rick Santorum ever right about anything?), in fact the overwhelming majority of climate scientists agree: Global warming is real and it’s our fault.
We need to elect politicians who understand that, and are willing to take action about it. Or else in the not too distant future, five trillions tons is going to seem like a drop in the bucket.
Astrophotographer Göran Strand was out on the night of Aug. 26 in Östersund, Sweden, when the sky erupted in auroral flames! He caught the whole thing in both time-lapse and real-time video, and it’s stunning.
Wow! Aurorae are formed when subatomic particles from the Sun are funneled down into our atmosphere by the Earth’s magnetic field. They zip down into our air, energizing atoms and molecules, causing them to glow. Each particle makes a more-or-less vertical line of glow, and huge streams of them make thin sheets of emission.
When we see these sheets edge on they can look like arcs, when seen from the side they look wider. When they’re directly overhead they fan out, creating what’s called a “corona” (you can see that starting at about 1:30 into the video).
I’ve written a FAQ about aurorae with links to how they form, why they have colors, and more.
And I had to laugh: At about 2:10, did you see the giant goblin face flashing pink and green?
I love stuff like that!
Strand is an amazing sky photographer, and I’ve featured his work many, many times here. Go check it out.
So you’re taking telescopic photographs of the Sun, watching the solar disk seethe under intense forces while blasting huge, towering prominences tens of thousands of kilometers into space, when your photo is completely ruined by a rude photobomber:
Or, in this case, it’s actually awesome because catching the International Space Station crossing the Sun’s face is precisely why you were observing in the first place.
That image was taken by top-of-his-game astrophotographer Thierry Legault. It’s a composite of several video frames from Aug. 21, timed perfectly to capture the ISS from his location. That’s no easy task; the tilt and timing of the orbit of the ISS coupled with Earth’s rotation means it only passes in front of the Sun as seen from the ground at very specific locations and times. If you’re off by a few kilometers you miss it. There’s software that makes this a lot easier now (like CalSky), but it’s not exactly simple.
Here’s the original video. Don’t blink!
Legault, who has taken so many pictures of ISS (and Shuttle and Hubble) transits that I’ve lost count (including one during a solar eclipse), told me this one excited him because he’s always wanted to catch the station moving directly across a prominence. There are two big ones in the photo—they’re huge blasts of plasma off the Sun’s surface, swept outward by the Sun’s violently shifting magnetic field. They can last for many hours, but don’t appear to change at all over the half-second or so it took ISS to cross the Sun.
That made things even harder for Legault. CalSky gives the central transit line, the locations on Earth where ISS passes over the center of the Sun. Legault then had to modify the calculation, moving a kilometer or two so that ISS would miss the center but pass over that prominence.
That’s dedication, folks.
Just above the ISS’s path is a pretty dramatic sunspot group, the twisting plasma between the spots glowing brightly. This photo uses a special filter (called an H-alpha filter) that only lets through a very narrow slice of color, specifically where hydrogen glows when heated. Usually, the fierce light at all wavelengths/colors washes detail out, but only letting this particular wavelength through means seeing lots of astonishing surface features on the Sun.
Pretty amazing. But for Legault, “amazing” is where he starts from.
Folks in Hawaii got a shock — or a thrill, depending on how much they knew about what they were seeing — when a very bright and dramatic “shooting star” blew across their skies on Aug. 31, 2015.
That’s one example of many (one I saw had a lot of swearing in it, which doesn’t surprise me at all).
Was it an asteroid? A sign of the Apocalypse? Superman?
Nope. It was the re-entry of Cosmos 1315, a Soviet-era satellite launched in 1981. The giveaway for me that this was a satellite and not a natural meteor was how slowly it was moving. Typical meteor speeds are many dozens of kilometers per second, and they zip across the sky in a second or two. Satellites orbit at about 8 km/sec, and can take a minute or more to clear the horizon. Also, satellites tend to break apart as the pressure and heat of re-entry take their toll, and you can see that’s what’s going on in the video.
Also, the Aerospace Corporation put the re-entry track right over Hawaii at just the right time. Seems pretty cut and dried.
I’ve seen hundreds of meteors (probably thousands), and only one satellite re-entry, a Russian booster that burned up over the US East coast back when I was in grad school. It was pretty awe-inspiring, moving slowly and gracefully across the sky, with bits falling off. A meteor usually stays in one piece unless it’s a really big one.
There are a lot of birds up there, and this stuff comes down all the time. Usually they fall over the ocean where no one sees them (the planet is mostly water, after all), but when they come down over populated areas we usually get lots of dramatic video and photographs.
Sometimes these can be a danger — ask this guy who lives downrange of a Chinese rocket launch site — but that’s extremely rare. Still, it’s something aerospace companies and national governments need to be concerned about, especially during test launches; debris from SpaceShipTwo came down in the Mojave after the test vehicle crashed in 2014, narrowly missing bystanders.
But what this tells me is — and stop me if you’ve heard this before — you need to look up! You never know what’s up there… and what’s coming down.
Tip o’ the heat shield to David Dickenson.
Do you think global warming is something that only affects us sometime in the future, decades or centuries from now?
Think again. Our planet heating up is affecting us now, and has been for decades. We’re already seeing a lot of serious problems due to it: extreme weather, more devastating hurricanes, wildfires, and sea level rise.
Of all these, the last seems most like science fiction. Seriously, the levels of the ocean are going up? It can’t be much, right?
Think again, again. NASA just released results from several satellite observations going back to 1992. Those 23 years of data show that the oceans of the planet have risen substantially in that time: over 6 centimeters (2.5 inches) on average, with some places on Earth seeing more than 22 cm (9 inches)!
This animation shows where the levels are going, and by how much:
The global sea level rise is driven by two major factors: One is that as water warms, it expands, raising the sea level. The other is that Greenland and Antarctica are melting, dumping 450 billion tons of water into the oceans every year. Every year.
So overall sea level is rising, but in some places it’s rising faster than others. For example, in the Pacific, heat travel east to west, so the eastern coasts of the Philippines and Japan have seen huge jumps in sea level the past two decades. Interestingly, sea levels have dropped in some places. Off the northeastern shore of the US you can see a drop. But in that case it’s because the Gulf Stream, a major warm ocean current, has shifted north somewhat, so levels have risen in the north but dropped in its wake to the south.
But those drops are highly localized. Globally, levels are on the rise.
The cause of all this is obvious and very real: global warming. As human activity — primarily dumping 40 billion tons of carbon dioxide into the atmosphere every year — causes the Earth’s surface temperature to go up, a lot of that energy is absorbed by the oceans, causing them to expand. Some of it is absorbed at the poles, melting ice there.
Sea ice melting at the north pole is bad enough, but the land ice melting is nothing short of catastrophic. Climatologists have already shown that the melting of the West Antarctica ice sheet may be unstoppable. We may be locked in — that is, inevitably going to suffer from — a full meter of sea level rise, three feet. This may take a century or more, but it’s coming. And while that may seem like a long time, think of it this way: A meter per century is a centimeter every year, an inch every 2.5 years.
Mind you, that’s vertical rise. Look at the slope of a beach and you can see that a small rise vertically means a lot of horizontal reach to the ocean, too. We’ll see beaches disappear, coastlines changed. More immediately, we’ll see storm surges do far more damage as it takes less rise in the water levels to inundate cities. Remember what the surge from Hurricane Sandy did to NYC? We’ll be seeing more and more of that.
This is the new normal. And the scary thing is not so much that the new normal is bad, it’s that with more warming, rising sea levels, and changing weather patterns, the new normal will continue to get worse. There may not be a normal any more.
Just as a reminder: With only a single exception, none of the GOP Presidential candidates has a reality-based view on global warming (the exception is George Pataki, who has no chance of winning), and those views range from unsupportable by facts to unhinged in the extreme. Even those of them who admit it’s real think it’s not human caused, or that we can’t do anything about it without hurting the economy (and that is 100% ultra-grade fertilizer; it’s worse to wait). Even this far out it seems certain the House will go GOP again in 2016, so having a climate-change-denying President will mean at least four more years of inaction bolstered by the smoke and mirrors of the noise machine.
And don’t forget that the GOP in the House is still trying to eviscerate NASA’s Earth science budget, which goes in large part to monitoring the effects of global warming. Why? Simply put, they deny the reality all around them.
And all that time, the temperatures will rise, the glaciers will melt, the sea levels will rise, and we’ll be that much deeper into a catastrophe that is already well underway.
If you have five minutes — and I think you do — then I urge you to go take a look at this lovely and wonderful comic by French artist Boulet. Yes, there are a few typos in the translation, but it’s charming and sweet, and expresses quite a few points I strongly believe in myself.
Science is not cold, nor scientists unemotional. If we were, we wouldn’t be doing this in the first place. For so many, it is our sense of awe and wonder that drives us.
Tip o' the pen cap to Jesse Anderton.
I’ll be honest: Every episode of Crash Course Astronomy has been fun to write, edit, and shoot. They all really have. But the past few episodes, and the next few to come, deal with one of my favorite topics in astronomy: What happens when a star decides to give up the ghost.
When stars die all sorts of fantabulous things happen: They explode, they leave behind bizarre ultradense objects, they fling gas into space that creates amazing and breathtaking shapes and colors.
This week, CCA is about what happens after stars like the Sun die: They become white dwarfs, and in the process blow out a series of winds that become one of the most beautiful sights in the sky: planetary nebulae.
I studied the planetary nebula NGC 6286 for my Master’s degree at the University of Virginia, investigating a giant circular halo of gas around it from the star’s original red giant wind. I had to simultaneously learn about planetary nebulae, the physics of interacting colliding winds, how gas radiates light, how the digital detector on the telescope worked (this was when such cameras were brand spanking new, so every thing about them was a learning experience), how to use the telescope, and how to write code to analyze the data. It was… interesting. Very difficult, but in the end I got results that were worth publishing.
My advisor, Noam Soker, is the man I mention in the video. I have never met a harder working astronomer in my life; he published a ridiculous number of papers, covering one small topic very well in each, and then moving on. I remember talking to him about why 6826 had an elliptical inner region, and he suggested it could be from a Jupiter-like planet orbiting the star. The problem was it would have to be very close to the star to be enveloped when the star became a red giant, and I thought that wasn’t possible — our Jupiter, after all, is over 700 million kilometers from the Sun, way too far to get swallowed up! And you can’t form a planet that big that near a star anyway.
Oh, me. This was five years before the first “hot Jupiter” was found, and now I wish we had emphasized this even more in our paper instead of just adding a single line about it! It turns out they may be quite common; they form farther out from the star and migrate inwards over time. I was pretty shocked when 51 Peg b was discovered, and seriously my first thought when it was announced was, “PLANETARY NEBULAE! OF COURSE!”
Yes, I think in all caps sometimes. It’s very funny to me that planets and planetary nebulae are in fact connected, especially since, despite their names, they are very, very different objects. But in science you find that everything’s connected in one way or another. It’s a tapestry, and every thread counts.
One of the things I love best is when someone looks through a telescope for the first time. Even better when it’s a kid; a simple glance through the eyepiece, a single moment, and a lifetime of joy and wonder is theirs.
During the week of the Perseid meteor shower in August, 2015, two dozen high school students participated in an Astronomy Camp held by the Oregon Museum of Science and Industry. They traveled to the high desert I that state to learn how to observe the sky, and then joined up with 600 other astronomers to participate in the Oregon Star Party.
Astrophotographer Ben Canales followed them, and took footage of the events. He created this wonderful video, “Make Me Dream”, which made my heart very happy indeed.
Some technical detail: Canales used the new Sony A7 mirrorless camera, which uses new technology allowing it to shoot video at — get this — ISO 100,000 (it goes even higher, but Canales said that's the highest he could go and get acceptable noise levels, even with some fancy post-processing techniques). That’s incredible; such a high setting means the camera was phenomenally sensitive to light, which is how he was able to get scenes showing both the young students and stars of the Milky Way in the background, even out of focus (which spreads the light out, making them even dimmer). I have got to try one of those.
The last shot, showing the persistent Perseid train, is fantastic. Make sure you watch all the way to the end of the video, too.
All the sky footage was nice, but what really made my smile grow was the expressions on the faces of the students as they set up and used their telescopes. It gives a real sense of accomplishment to learn how to use a telescope; they can be finicky, and frustrating. But when things start to click, the whole sky becomes yours. When you know your way around the night sky it’s a treasure map… but it’s also the treasure itself.
Canales captures this perfectly. But what else do I expect from someone who took this picture, one of my all-time favorite astrophotos?
That is how I feel all the time when I am out under the stars. I highly recommend it.
I used to play a lot with soap bubbles. Long after I grew up, I mean.
Scientifically, they’re very interesting; they explore such topics as thin film surfaces, optical interference, least-area surfaces, shape packing, and all kinds of chemistry.
Also, they’re pretty and silly and fun.
But one thing that never occurred to me in all that time is that soap bubbles make a pretty good stand-in for hurricanes. It might surprise you that such a delicate and fragile structure might analogize one of the most powerful and destructive events on the Earth’s surface, but sometimes in science scale isn’t a problem. It doesn’t matter if it’s small or big, the interacting forces are what matter.
My friend Dianna, aka Physics Girl, explains in this great video:
Dianna’s a great science communicator; she has a knack for making complex issues simple, but not too simple. You should check out her other videos, especially this one on mirrors flipping right and left (… or do they?), and this one on vortices in swimming pools.
Bubbles are a lot of fun, and the science they show us is astonishing and beautiful. Especially, in my not-so-unbiased opinion, when they’re on the ten trillion kilometer or so scale.
As an aside, congratulations to Dianna for now being a part of the PBS Digital Studios family! They’re partners with Hank and John Green in producing Crash Course Astronomy, so I’m a big fan of them.
Ceres is the largest asteroid in the solar system*. The Dawn spacecraft has been orbiting it since early this year, and a few months ago it spotted something really weird: a 6-kilometer tall mountain just sitting all by its lonesome on the surface.
Since that time Dawn has lowered itself closer to the surface of Ceres, where it can take higher-resolution images. A new photo of the mountain has only made things weirder:
What the heck is going on with this rock?
The mountain, still unnamed, is just so odd. It sits on what looks like a relatively flat area (though saturated with craters, like the rest of Ceres). It almost looks more like a mesa, with a relatively flat top.
Note the flanks. In this image, the Sun is shining from the right (I flipped it from the original for ease of viewing in a browser), so the right side of the mountain is bright, and the left in shadow — but it turns out that difference in shading is real; one side really is brighter than the other. That’s more obvious in this animated tour of the mountain that uses shading in different images to generate topographical relief:
Note the bright streaks running down the sides. We know Ceres has a lot of water ice in it, but I can’t convince myself that’s what we’re seeing here. The sides of the mountain get a lot of sunlight, and even though Ceres orbits out past Mars, it gets warm enough on its surface that direct sunlight should make the ice sublimate (turn into a gas).
The base of the mountain is pretty sharply defined all the way around. It even looks like there’s a small bit of material piled up around the base on the side facing the crater; you can see slightly brighter arcs here and there. That’s probably mass wasting, material that has slid down the sides. However, there’s not very much of it!
I’m not saying this mountain is a mesa, but suppose for a moment there might be similar processes at work here. Mesas are shaped the way they are due to erosion. What could erode something on Ceres? If the bright stuff really were ice, then you'd expect the material to slump and fall down the sides as the ice sublimates, piling up at the base. We do see some of that, but not nearly enough (see below for more about slumping). That's one reason why I'm skeptical the bright stuff is ice. The resemblance to a mesa is probably just coincidence. UPDATE, Aug. 26, 2015 at 15:45 UTC: Alan Boyle at Geekwire talked to a planetary scientist who thinks the bright streaks may be from salt. That makes sense, but we still can't know just yet, since distiguishing salt from ice is very hard with just visible light data.
Dawn was about 1500 km above Ceres when it took that shot on Aug. 19. In a couple of months it will begin to lower itself to a height of only 375 km! It'll reach that orbit in December (ion engines are efficient but very low thrust, so it takes a while to change orbits). The resolution will increase by a factor of 4, and features just 150 meters or so across will be visible. Hopefully that will help resolve (literally) some of the mysteries of this bizarre feature. It’ll be interesting to get a better view of the terrain around the mountain, including that soft trough snaking up and slightly around the mountain. Coincidence? Or are they related?
And because why not, here’s another spectacular photo from Dawn:
Yegads. The big crater at the bottom is called Gaue, and is about 84 km across. Like lots of other craters on Ceres, the rim slopes look steep due to material sloughing off; you can see it piled up all along the inside rim on the crater floor. To my untrained eye, I see a lot of material around it that looks like it might be part of the ejecta apron, material blown out of the crater when it formed. There’s a subtle change in texture near the top left of the image, where I’m speculating the ejecta blanket ended.
Lots of big craters have central peaks, where material rebounds upward after the impact. But the center of this crater is sunken! That may be due to lots of softer material underneath (ice?).
I’ll remind everyone that I’m not a planetary scientist, and while I’m fascinated by geology I’m hardly an expert. But these images are new, and even the Dawn scientists have only just received them. I’ll be very interested to hear their own conclusions.
These images are fantastic, and I can’t wait for December. As amazing as the current data are, those will be even better.
* Some people call it a dwarf planet. I don’t. I got a note from a scientist on the Dawn team who told me they prefer the term “protoplanet”; Ceres and Vesta were both well on their way to becoming full planets before they stopped growing, whereas asteroids tend to be debris, or smaller objects that are fodder for the growth of protoplanets. I rather like that term, and I may have to write up more about it in the future.
I suspect that when most people think about asteroids approaching Earth, they picture them coming from deep space, out past Mars and Jupiter.
But there’s a substantial population of asteroids where the rocks spend most of their time inside Earth’s orbit, closer to the Sun. These little beasties are hard to find because they tend not to stray too far from the Sun in the sky, so they’re up mostly during the day or twilight hours.
For my biweekly column at Sen.com, I wrote about a newly discovered asteroid called 2015 QM3 that is on such an orbit, swinging it past not just Earth, but also Venus and Mercury! It’s a curious object, getting close enough to all three planets that over millions of years its orbit is certainly unstable. Not many such asteroids are known (just 17!) so any time we find a new one it helps us understand the complicated dynamics of near-Earth objects.
My articles for Sen.com are subscription only, but for $5 a month you get access to a lot of pretty cool astronomical info. I check it for news and interesting photos every day. You should too.
My thanks to my friend and esteemed astronomical colleague Amy Mainzer for her help with some info about QM3 … and also for announcing the asteroid in the first place
The latest from the Here-We-Go-Again-Department: An Internet rumor has gone viral that NASA is covering up information about a giant asteroid or comet that’s going to hit the Earth in September, sometime between Sept. 15 - 28.
Let me be clear: No.
Let me be less clear but more snarky: Go look at a bull facing north. Now walk around to the south side. See what comes out? Yeah, this asteroid impact rumor.
There are a lot of reasons this story is nonsense.
- It was on Before It’s News, a crackpot website that is to accuracy what Donald Trump is to humility. I also try to avoid getting my news from sites that leave vowels out of their name.
- The claim that a comet over two miles wide will hit the Earth in a month or two is ridiculous right away: It would be one of the brightest objects in the sky. I think someone might have noticed.
- NASA couldn’t cover something like this up. First of all, they’re not the world’s only space agency. Second, NASA doesn’t control all the telescopes in the world. Or even really any. There are tens of thousands of astronomers all over the planet who would have seen and been talking about an object that big headed our way.
- As Ron Baalke pointed out, NASA announced two asteroid impacts, one in 2014 and the other in 2008 — both were small rocks that burned up in our atmosphere, but it shows that NASA has not covered such things up in the past.
- Also, how many times have we heard this kind of crap from breathless pseudoscience sites? Many, many, many, many, many, many, many, many times.
- And how many times have they been right? Oh yeah: none. None more times.
This latest in the long-running series of hoax impact claims got spread around so much that the folks at NASA felt they had to issue a debunking of their own:"There is no scientific basis -- not one shred of evidence -- that an asteroid or any other celestial object will impact Earth on those dates," said Paul Chodas, manager of NASA's Near-Earth Object office at the Jet Propulsion Laboratory in Pasadena, California. In fact, NASA's Near-Earth Object Observations Program says there have been no asteroids or comets observed that would impact Earth anytime in the foreseeable future. All known Potentially Hazardous Asteroids have less than a 0.01% chance of impacting Earth in the next 100 years.
I’m glad NASA went to the trouble to write and release that, but it ticks me off. People at NASA have better things to do than squelch silly Internet nonsense. That's your tax dollars at work, folks.
But a bigger reason I get angry about stuff like this is that it scares people. It really does; whenever these rumors go around I get plenty of anxious emails and tweets asking me if it’s true. I don’t know why sites like Before It’s News and the others post fertilizer like that story — maybe it’s just for clicks, or for attention, or because they get their jollies by scaring people for no reason whatsoever.
But every time they do they are frightening people, they are wasting time, and they’re also contributing to the overall erosion of public trust in science.
And that is something we really, really don’t need.
On Aug. 29, 2015, a few days from now, it will have been 1500 days that NASA has been relying on Russia to hitch a ride to the International Space Station.
It was that long ago when the Space Shuttle Atlantis landed at Kennedy Space Center — the last Shuttle flight to the ISS, and in fact the last Shuttle flight of them all. That was the last time an American rocket carried humans into space.
As I have made clear many times, I do not begrudge President Bush for canceling the Shuttle program, nor President Obama for canceling its replacement, the Constellation program, which was running severely over budget and behind schedule.
What I do begrudge is a Congress that has made this situation far worse by underfunding the Commercial Crew Development program, which was specifically designed to allow commercial companies to pick up the slack and get Americans back into space on board American crewed vehicles.
Every year, NASA works with the White House to create a budget. The amount the President has asked to fund Commercial Crew over time would have been enough to begin the first launches this year, 2015.
But over the past five years, Congress has consistently underfunded Commercial Crew, usually by several hundred million dollars every year, as much as 25 percent of the requested funds. The total amount that’s been shorted is about a billion dollars.
Yes, a billion.
It’s gotten so bad that NASA’s Chief Administrator, Charles Bolden, sent a letter to the Congressional committees that oversee NASA’s budget. You should read it; it’s not long. Here’s a choice quotation:In 2010, I presented to Congress a plan to partner with American industry to return launches to the United States by 2015 if provided the requested level of funding. Unfortunately, for five years now, the Congress, while incrementally increasing annual funding, has not adequately funded the Commercial Crew Program to return human spaceflight launches to American soil this year, as planned. This has resulted in continued sole reliance on the Russian Soyuz spacecraft as our crew transport vehicle for American and international partner crews to the ISS.
That last sentence is critically important. Every launch we miss because Congress has underfunded Commercial Crew is a launch we have to pay Russia for — and Putin’s government has been consistently jacking up the price for years.
My friend Mika McKinnon cranked the numbers, and found that it will cost upwards of a half billion dollars to put six astronauts on the space station in 2017 (Bolden’s number is in that same ballpark), but it would cost 75 percent of that to launch them on American vehicles — and that money would be staying here in the US, not being sent to Russia.
Why are we investing in Russia, and not ourselves?
Perhaps because many of the Congresspeople who are in charge of NASA’s budget right now are more invested in building the Space Launch System, the NASA rocket system designed to replace the Shuttle.
My opinion on SLS and the Orion capsule are a matter of record: I think, given the cost, that money would be far, far better spent on commercial rockets. SLS is so expensive that I worry there won’t be money left in the budget to do anything with it. I’m not the only one who thinks that either. Nor am I the only person who has been outspoken against SLS. Lori Garver thinks it’s a waste of money, too, and she is former Deputy Administrator of NASA!
So why is Congress so gung ho for SLS? Maybe because so many Congresspeople have people building SLS in their states and districts.
For one very critical example, space journalist Eric Berger points out that Senator Richard Shelby (R-Alabama) is the chairman of the Senate’s committee that funds NASA, and he has Marshall Space Flight Center in this district. Marshall is where SLS is being designed and built. Shelby also has a history of throwing roadblocks in the way of funding Commercial Crew and SpaceX.
Berger also points out that Congress has made it clear that other government funded agencies, like the Department of Defense, are not allowed to buy hardware from Russia. Yet here we are, with that same Congress forcing NASA to pay Russia to the tune of nearly 500 million bucks for one year.
For their part, Congress has asked the President why he is underfunding SLS. That’s pretty audacious, given these facts (and given that Congress actually funded SLS at levels higher than what NASA requested). Coincidentally, the amount of money cut from Commercial Crew is about the same as what we’ve been sending to Russia for seats on their Soyuz. I'll also note that at the very best, SLS won't be ready to put humans in space for four years after a commercial vehicle could. How many billions of dollars would that mean giving to Russia to cover that gap if Commerical Crew is still underfunded?
Let me be clear: I love NASA. I think they represent the best of what we humans can do. I also know they are tied in knots trying to appease the whims of Congress and the White House, two winds that blow in vastly different directions. I have taken the President to task before for mysteriously and bafflingly underfunding planetary exploration, but in this case the White House has it right.
I know that SLS and Orion are too big and moving forward too much to cancel now. That’s a political reality, and while I can’t make my peace with it, I can understand its truth. But this nickel and diming Commercial Crew must stop. Boeing and SpaceX need that money to keep the schedule, and if Congress can’t find it, then we’ll just be sending payload bays full of cash to Russia for many more years to come.
The solution is easy. The amount of money we’re talking about here isn’t much in terms of government spending, and it will save hundreds of millions of dollars per year in the long run, all the while promoting American industry and ingenuity.
Congress: Increase NASA’s budget by the amount needed. Fund SLS and Orion as you see fit, but don’t do so at the cost — literally — of Commercial Crew Development.
It’s time to take a step out into the greater Universe in Crash Course Astronomy. Sure, exoplanets and brown dwarfs got us out of the solar system, but when you want to understand what’s going on in the cosmos, you have to look at stars.
We dipped into them in Episode 26, but now it’s time to start poking into their guts in detail. The basic events in any star’s life occur in low mass stars, ones from red dwarfs up to a few times the mass of Sun. Things get different when higher mass stars start to die, so we’ll hit that when we get into that end of the HR diagram (what’s that, you ask? Click the Episode 26 link!).
In Episode 27, “Low Mass Stars”, I talk about their lives and deaths. Mind you, since the Sun is in that range, well, we’ll have to look that eventuality in the face as well. And since the Earth orbits the Sun, you can guess what that means for our fair world.
The good news is that the events that will unfold won’t do so for billions of years. Billions, with a b. We’ve come a long way in the past century or two — heck, we understand stars well enough to make educational videos about them — so who knows where we’ll be in a hundred million centuries.
In my book, Death from the Skies!, I cover all this, including the death of the Sun and likely vaporization of Earth. I also talk about the idea of using the gravitational effects of slinging thousands of big asteroids past the Earth to move its orbit out so that it can maintain a constant temperature while the Sun goes red giant. There’s a great journal paper about this online; if you want details they’re there. It’s what I based that part of the chapter on.
See? There’s hope! And if we’re being honest, my biggest hope is that we won’t need to do this to save the Earth at all. By then, instead, we’ll have spread out into the galaxy, and those beyond. A billion years is a long time.
The Crash Course Astronomy playlist is an index to all the episodes online so far. One-stop shopping, folks.
Oh, I love a good science pun.
Don’t get it? Well, what’s even better than a science joke? When I get to explain one*!
Scattering is a term we use in physics to describe when two objects collide, interact in some way, then head off in different directions. There are lots of different kinds of scattering, but if you want a super simple example, think of two billiard balls hitting each other and then rebounding.
Sometimes, when two objects scatter off each other, they exchange energy. The object with lower energy steals a bit from the higher energy object. This is generally expressed as velocity, so (for example) a slow moving particle hitting a faster one speeds up, while the faster one slows down. It depends on the particle masses, their velocities, directions, and lots of other stuff.
It happens with particles and light, too. A high-energy photon (a particle of light) can hit an electron. The photon loses energy, while the electron goes careening off at higher speed.
This kind of interaction was first discovered by the physicist Arthur Compton in 1905, and he won the Nobel for it in 1927. In his honor, we call this Compton Scattering.
It turns out the reverse works, too: low energy light can hit a high-velocity electron, steal its energy, and turn into a much higher energy photon, like an X-ray or a gamma ray. Lots of processes in astrophysics create high energy particles; matter swirling around a black hole, particles getting batted around in supernova shockwaves, and more. When these impact light (like starlight), the photons get pumped up to X- and gamma rays, and we can detect these with our orbiting telescopes.
So now does the joke make sense? The image in the background is a map of the sky taken by the Fermi gamma-ray observatory. Some of the gamma rays in that image are from inverse Compton scattering.
Well, it made me laugh.
Even better? I mentioned to ClockWorkSimon that some of the gamma rays in the map are from inverse Compton scattering, so he inverted the image:
Ha! An even dorkier physics joke.
If you laughed at that picture, then congrats! You’re a physics nerd. Give yourself +π Internet points, and go read the Wikipedia entry on equipartition of energy for fun.
* Because the only thing funnier than a joke is explaining why it’s funny.
Last week, the nothing-short-of-phenomenal Cassini spacecraft made its last close pass of Saturn’s icy moon Dione.
Yes, last. After more than a decade orbiting Saturn, the Cassini mission’s days are numbered. It will end late in 2017, after deservedly being extended twice (and having toured the Saturnian neighborhood since 2004). So, in many cases over the next few months, when it passes by a moon it will be for the last time.
And so we have a final flyby of Dione. Cassini flew past it at a distance of less than 500 km on Aug. 17, 2015, taking quite a few images, including some with a stunning resolution of just 10 meters per pixel! Though motion blurred bit, that means features as small as a house could be seen. Not bad, from a space probe that’s a billion kilometers from Earth!
Dione is small, about 1120 km across, a third the size of our own Moon. Its density is low, meaning it’s mostly water ice, most likely with a smallish core of rock. In this image, taken when Cassini was still 170,000 km from the moon, gives you a sense of the beating it’s taken over the eons (this is a mosaic of nine separate images, one taken with a lower resolution camera, which is why part of the moon is blurrier). That big multi-ringed impact basin to the lower right is called Evander, and it’s about 350 km across. The hexagonal crater to its upper left is Sabinus; older, higher-resolution images show that the crater rim is slumped in, probably due to the low strength of the icy material. Many of the craters on Dione are low relief for that reason.
Usually, moon pictures like this have a black background, so why doesn’t this one? Because, lying just another 370,000 km past Dione, Saturn is filling the field of view! The black stripes running across the picture, going behind Dione, are Saturn’s rings, seen nearly edge-on here. Saturn is 100 times wider than Dione, to give you a sense of how little of the planet you’re seeing here.
This view, taken from 73,000 km distant, shows a little more context. At the bottom you can see the shadows of Saturn’s rings on the planet’s cloud tops.
From 158,000 km, Sabinus dominates the view of Dione’s surface. Note the central mountain filling most of the crater floor; that’s a common feature in big craters, caused as material rebounds after the impact. Seen against the blackness of space, Saturn’s rings split the background, again nearly edge-on during this encounter.
Up close, the true nature of the surface is more obvious. This shot was taken when Cassini was a mere 750 km above the moon’s surface! It’s an oblique view, showing the moon’s edge, and you can see that the surface is positively saturated with craters down to the smallest scales visible (about 200 meters across). The image looks grainy because it was a short exposure, to prevent too much motion blur as Cassini zipped past.
Taken less than 600 km from the surface, this view shows Dione near the terminator, the shadow line separating day and night. It’s stunning. The features look soft, eroded. This was taken with Cassini’s wide-angle camera; near the middle an inset shows the view from the narrow (higher power) angle camera. At full resolution the narrow-angle image is pretty rough, but shows craters in the Sun’s shadow yet still illuminated softly by the glow of Saturn, which dominates Dione’s sky.
I love this picture, if only because of how much it looks like our own Moon. I can easily imagine looking out the window of the Lunar Module and seeing this terrain approaching. Again, a higher-resolution inset is included, the view from the narrow-angle camera. The full res version is motion blurred, but again shows just how impact-laden this tiny world is.
Near the top is a short, winding canyon, looking very much like a rille — on the Moon, these are caused by lava flows. Is this the same sort of feature, but due to water flowing after an impact?
Farewell, Dione. This magnificent shot, taken after Cassini passed the moon, is a mosaic of several images taken from a distance of about 60,000 – 75,000 km. The vastly different angle between Cassini, the moon, and the Sun puts Dione in a crescent phase as seen from the spacecraft. The low Sun angle accentuates relief on the surface, highlighting craters and some of the cliffs that line the moon. Those cliffs were discovered in Voyager images, but their true nature as icy cliffs not understood until Cassini visited the moon for the first time in 2004.
And that is the end of the show for Dione. But not for Cassini, not yet. It still has over a year of travels left, including visiting tiny moons far from Saturn that have only been seen from great distances. What secrets will they reveal?
And the grandest adventure is yet to come: Over the last few months of the mission, Cassini will fly between Saturn’s rings and the top of its atmosphere, providing what will be incredible views. And then the final step: Cassini will be aimed into Saturn itself, plunging into it, burning up and crushed by the mighty planet’s atmosphere. But as it does it will return a last precious few bytes of data, telling us more about the ringed wonder even as it lives its final moments, a few drops of scientific knowledge more for us a billion kilometers sunward.
We should all do so well in our lives.
Planetary nebulae are among my favorite objects in the sky. These are gaseous shells thrown off by middle-weight stars as they die, ethereally interacting winds that form fantastic and colorful cosmic baubles.
Many are easy to see in small telescopes, so the amateur astronomer in me loves them, and the physics behind them is fascinating, rich, and intricate, inspiring the science-minded astronomer in me (in fact; I wound up studying them for both my Masters and PhD, and went on to analyze even more as a professional with Hubble).
I have seen images of the planetary nebula called ESO 378-1 before, but the European Southern Observatory just released a new, gorgeous, and high-resolution shot of this lovely object:
Very cool. But what are you seeing?
What we have here is a dying star. As a star ages, its core (where the heat is generated) shrinks and heats up. This puffs up the outer layers — when you heat a gas, it expands — and the gas on the surface starts to blow away in a dense, slow wind. Eventually, so much of the outer layers blow off that the hotter lower layers get exposed. The wind blown off gets less dense and much faster, catching up with and slamming into the older, slower wind.
The resulting nebula (gas cloud) is lit by the hot exposed core of the star, and glows. The shape we see depends on what the star was doing when it blew the winds. If it was just sitting there, the winds expand as spheres, and the result looks like a soap bubble.
But with ESO 378-1, the star must have been spinning rapidly. Perhaps, in its twilight years as it expanded, it swallowed up a bunch of its planets, which would have spun it up like whisking scrambled eggs. As it spun, the gas blew off preferentially along the star’s equator due to centrifugal force. This created a dense ring of gas.
When the star started to blow of the faster wind, it slammed into this dense ring and slowed down. But up and down, along the poles of the star, the gas was free to expand. It formed a more elongated, barrel shaped object (this diagram of another such object may help you picture it). We see that barrel at a slight angle; if you look at the interior of ESO 378-1 you can see it has two circular darkish regions, the top and bottom of the barrel.
It might be easier to see that in this photo of the Owl Nebula, a planetary nebula in Ursa Major:
See the two dark circles? Same thing. And you can see why ESO 378-1 has the nickname the Southern Owl (the original Owl is quite far north; this one is south of the celestial equator). They look very similar, and almost certainly have similar origin stories.
As for the colors, rarefied oxygen glows blue, and hydrogen is red. I suspect the red at the top is actually due to gas floating between the stars being swept up (what astronomers call, for obvious reasons, “snowplowing”) as the planetary nebula gas expands. There must be more gas above than below, so we see a brighter rim of red there. Other planetaries do this too.
I noticed that this picture got a lot of press when it was released, but most stories simply repeated the brief info in the press release. But c’mon, you know I can’t just do that. Y’all deserve to know more than that! Plus, planetaries are near and dear to me, and I love thinking about how they get all their weird and wonderful shapes. I’ve written about them many, many times, and I urge you to peruse them. They truly are amazing objects.
You’d think that by now, deep into the 21st century, we’d have a pretty good handle on how something as common as lightning works.
But in fact there are still lots of mysteries to these gigantic bolts of electrical current, and a lot of their behavior is either unknown to or misunderstood by the public.
For example, have you ever heard of sprites? These are extremely fast and faint discharges that occur above thunderstorms. Way above, actually, from 50 – 90 km up in the atmosphere. Most thunderstorm-producing clouds only reach a dozen or so kilometers in height, but clearly their reach extends much higher.
Sprites are beautiful and fleeting, and extremely difficult to photograph. Well, until recently, when more sensitive digital cameras became commonplace. One thing that makes it tough is that the sprites occur so high up you only really spot them above storms on the horizon; if you’re closer the cloud itself blocks them (the fantastic photographer Randy Halverson caught a sprite in a storm photo that I wrote about a while back).
… unless you have a better vantage point, like, say, above the clouds. Way above, as in space. Then you can get fantastic shots like this:
That was taken from the International Space Station on Aug. 10, 2015, when the orbiting lab was over the west coast of Mexico. Facing east, looking out toward the Yucatan peninsula, there were several thunderstorms in view, and the one on the right, very near the Earth’s limb, produced a sprite. See it? The picture at the top of this article is a close-up.
How bizarre is that? It has the classic jellyfish-shaped top with dangling tentacles, and is probably a few dozen kilometers across, though it’s hard to tell exactly.
So what causes these? I had to do some digging, but came upon this informative (though technical) paper describing them. Big convective cloud systems can generate huge electrical potentials — separation of charges — and when it gets big enough you get a discharge of lightning to restore the charge balance.
This electric field can extend upwards above the cloud, to the height of the mesosphere (and into the lower ionosphere) at nearly 100 km. In general, it’s too small to generate any kind of discharge, and in fact, the majority of lightning storms don’t make sprites.
What the authors of this paper found is that certain atmospheric conditions really help. Rising air in a thunderstorm can make gravity waves, ripples in the air that move up and down. This causes the air density to increase, and that can be just enough to give the right conditions to make sprites. The air is ionized, the charges separate, and then you get a discharge similar to normal lightning creating the sprite.
The details are far more complex than this, of course, with the tendrils flashing and combing to create the other effects. One thing I think is neat: The red is from nitrogen molecules and oxygen atoms in the upper atmosphere, the same reason the aurorae sometimes glow red.
If you’re curious, the bright object in the sky is the waning crescent Moon, highly overexposed, and you can see Orion rising to the right. The exposure time was 1.3 seconds, and it looks like the camera got bumped a bit during the exposure; the stars make wiggly shapes. The greenish glow above the limb of the Earth is airglow, caused by the slow discharge of sunlight energy stored up by atmospheric molecules during the day.
In related news, and in a happy coincidence of timing, I was contacted by Steve Cullen, a software executive and someone who loves astronomy, about this very topic. He heard that Hurricane Hilda had quite a bit of lightning off the coast of Hawaii recently, so he checked the Canada France Hawaii Telescope's CloudCam images — sure enough, he found some very interesting upper atmospheric lightning!
In that footage you can see the red flashes. To my inexperienced eye they look a lot like sprites, but Cullen tells me they are actually "Gigantic Jets", a similar but different phenomenon. For one thing, sprites are associated with lightning, but jets aren't always. Sprites can be higher in the atmosphere as well.
In another coincidence, Cullen works with astrophotographer Rogelio Andreo Bernal; I just posted photos and video Bernal took of the Perseids! Incidentally, Cullen and Bernal are both behind Starscape Gallery, an astrophotography gallery on the Big Island of Hawaii. Bernal is one of my favorite astrophotographers. I may have to pay the gallery a visit someday.
Tip o’ the blue jet to Stuart Rankin. P.S. Due to a cancellation, there are still four slots left for the Science Getaway to Hawaii Sept. 14 - 20! It'll be a fantastic adventure.
It was taken by astrophotographer Brad Goldpaint (who has been featured on this blog many times) on Thursday. It’s a composite of photos he took at Mount Shasta in California over the course of four hours during the shower. As you can see, they all appear to radiate away from one point in the sky: The “radiant,” in between the constellations of Perseus and Cassiopeia (technically within the border of Perseus, hence the shower name).
Well, almost all of them do. You can also spot a couple of random, sporadic meteors. That’s not surprising; on a normal night the Earth gets hit by 100 tons of cosmic debris anyway. You’re bound to get a few of those meteors during a shower.
Bonus! In the earlier article I had a photo taken by Rogelio Bernal Andreo of the shower from his location in Hawaii. I mentioned that one of the meteors created a persistent train, a long-lasting vapor trail after it disintegrates. Andreo created a time-lapse animation of it, and you can see it flare brightly, then the vapor blow away.
Cool. Now I can’t wait for the Leonid and Geminids!