Bad Astronomy Blog
On the afternoon of Thursday, Oct. 23, 2014, the Moon will pass in front of the Sun.
What we’ll see is a partial solar eclipse, where the Moon passes along a chord of the Sun’s face, never completely blocking it out. At maximum eclipse the Sun will look like a thick crescent, the dark disk of the Moon moving across it.
This is a very cool event, and it favors Canada and the United States; it’ll be visible in nearly the entirety of both countries. The exception is the extreme northeast, where the Sun will be setting as the eclipse starts (whether you see anything or not from that area depends on your exact position; see below).
Fairly Warned Be Ye, Says I
First, let’s get this out of the way: NEVER LOOK AT THE SUN WITHOUT PROPER FILTERS. You probably won’t do severe or permanent damage to your eyes by looking at the Sun with your eyes alone, but I’d advise against it (especially for younger children, who have clearer lenses in their eyes that let through more damaging UV light). AND DON’T EVER EVER EVER LOOK AT THE SUN THROUGH A TELEPHOTO LENS, BINOCULARS OR A TELESCOPE without proper filtration, and honestly, unless you really know what you’re doing, just don’t do it.
You might think sunglasses are OK, but they’re generally not. They can make it worse; they block visible light from the Sun, so the pupil in your eye widens. That can let in more harmful UV and infrared light.
If you want to see this event properly and safely — and you should, because eclipses are very cool — I urge you to find a planetarium, observatory, or local astronomy club near you and let experts handle the equipment for you. They might even have a pair of eclipse glasses you can use (it’s too late to order ones now, but there will always be more eclipses so I suggest you order some; they’re cheap).
I have more about safely observing the Sun in a post about the Venus Transit from 2012; I strongly urge you to read it before going out to take a look.
OK, so what does all this mean?
Here’s how this works. The Moon orbits the Earth once per month, and the Earth orbits the Sun once a year. The Moon’s orbit is tilted to Earth’s orbit by about 5°, so as it goes around the Earth it passes through the Earth’s orbital plane every two weeks or so. If the Moon’s orbit weren’t tilted, we’d get a solar eclipse every month when the Moon passed between the Earth and Sun. Since it is tilted, though, sometimes it’s “above” the Sun at new Moon, and sometimes “below”. We only get eclipses rarely because the Moon has to be crossing the plane of Earth’s orbit at the same time it’s new Moon, so that it gets exactly between us and the Sun.
On Oct. 23, the geometry is close but not quite perfect. Instead of passing directly in front of the Sun, cutting straight across it, the Moon passes the Sun at an angle off-center, so it only partially blocks our star. That’s why this is a partial eclipse, and not a total one.
In a lunar eclipse, the Earth gets between the Sun and Moon, and casts its shadow on the Moon. The event happens on the Moon, so everyone on Earth facing the Moon sees it at pretty much the same time.
But a solar eclipse is the Moon casting its shadow on Earth. The Moon is moving, orbiting us, and the Earth is rotating as well, so what you see and when you see it depends on where you are (it’s like sunset, which you see at a different time than someone east or west of you).
On the left is an animation showing the view from above the Earth, looking down on the US during the eclipse. The curved line sweeping around clockwise is the terminator, the day/night line. The big grey distorted circle is the physical shadow of the Moon. You can see that over time it moves roughly eastward and southward, the combination of its motion and the Earth’s spin. If you live anywhere inside the path of that shadow, you’ll see an eclipse. The closer you are to the center of the shadow, the more of the Sun will be blocked.
So when will you see it? If you happen to live near a big city, here’s a table showing eclipse times, and there’s also an interactive page where you can enter your location and it’ll tell you when the eclipse happens.
As an overview, here’s a map showing timing and percentages of the Sun blocked.
It looks daunting but it’s not that hard to interpret once you get used to it. The more-or-less horizontal curves are marked 0.20, 0.40, 0.60 and 0.80; those are telling you how much of the Sun is blocked. I’m in Boulder, Colorado, just south of the 0.60 line, and so the most I’ll see is about 56% of the Sun blocked. That’s not enough to really notice it getting any darker out.
The more-or-less vertical lines tell you the time of greatest eclipse in UTC (subtract 4 hours for Eastern, 5 for Central, 6 for Mountain, and 7 for Pacific times). Boulder is just to the east of the 22:30 UTC line, and for me I’ll see the most amount of Sun blocked (what’s called greatest eclipse) at about 22:34 (16:34 or 4:34 p.m. local time).
Viewing and Photographing the Eclipse
First off, again, here are some tips on how to safely observe the Sun, and you can find a lot more here. I’ll reiterate a few here.
If you have certified eclipse/solar viewing glasses, you’re OK. These are designed to block the dangerous IR and UV light from the Sun, while cutting way down on the visible light. The Sun looks like a small disk, and the eclipse will look really cool just like that. Again, don’t use sunglasses, even if they are UV blocking! They can actually increase the damage to your eyes.
I’ll add here that there is a monster sunspot (AR 2192) that is crossing the Sun’s face right now, and that’ll make a very dramatic feature to see during the eclipse.
If you have a pair of binoculars you can use them to project the Sun on a piece of white paper. Again, seriously, don’t look through them at the eclipse unless boiling your eyeballs is something you’re hoping to do. Also, be warned: The Sun can heat up the inside of your binoculars, and can damage them. I’ve used this technique many times with no problem, but I have pretty decent equipment. Plastic lenses, for example, might not fair well. Proceed at your own risk.
First, block one of the big lenses with a lens cap or something opaque, so you’re only using one half of the binoculars (otherwise you get two images). Get a big piece of white paper (poster board is great for this) and prop it up facing the Sun. Hold the binoculars so that you can see the shadow of them on the paper. Orient them so that the shadow of the binoculars is as small as possible; when they’re aligned with the Sun you’ll see an image of the Sun on the paper. Move the binocs towards or away from the paper to get the Sun the right size, and focus them. This takes some practice, but after a few minutes you’ll get the hang of it.
You can also do a variation of this projection method with a telescope, but I really, really don’t recommend it. ‘Scopes gather a lot of light and focus it down into a tight beam, and that can severely damage eyepieces and/or the telescope itself. And NEVER use one of those little “Sun filters” to screw into your eyepiece! Those can heat up and crack, and under some circumstances shatter, sending glass shard outwards at high speed. Not a good idea.
If you happen to have a telescope with a Mylar Sun filter that goes over the front end of the ‘scope then you’re probably OK. Just make sure you know what you’re doing. I’d hate to see anyone get hurt, or equipment get damaged, from observing the eclipse.
And finally, if it’s cloudy where you are, don’t despair! Eclipses are always live streamed from various locations, so you’ll be able to watch it on your computer. The Coca Cola Space Science Center will have a webcast, and I’ll add more here as I find out about them.
The next solar eclipse is on Mar. 20, 2015, visible from Europe and Asia; the next one visible from the US will be the great total eclipse of Aug. 21, 2017, which will cut right across the heart of the country. That one will be a big deal.
So if you’re in North America, try to catch this one; it’ll be three years before the next. There’s something wonderful and, yes, other-worldly about eclipses, even partial ones. If you get a chance to watch (safely), take it. And if you do get pictures, send me links (either via email, or on Twitter) — I’m hoping to put up a gallery of the most clever and cool ones. I have a gallery from the May 2012 solar eclipse that might give you some inspiration.
Yesterday, Oct. 19, at approximately 18:30 UTC, Mars got buzzed by a comet.
The comet, named C/2013 A1 (Siding Spring), passed just 130,000 km (80,000 miles) above the surface of Mars, the closest cometary encounter with a terrestrial planet ever seen (the adjective is because Jupiter has been hit by several comets and asteroids in the past few years).
Siding Spring is an Oort cloud comet, meaning it came from the very remotest regions of the solar system, almost certainly plunging into the inner system for the first time after billions of years in the dark. It chose quite a path for its first trip here! Mind you, the comet got three times closer to Mars than the Moon is to Earth. This was a close shave indeed.
NASA and other space agencies took precautions, moving their orbiting probes to the far side of the Red Planet during closest approach, while the rovers were pretty much on their own. Happily, they all appear to be fine, even after the comet dropped tons of material into the atmosphere at dozens of kilometers per second.
We’re still awaiting images taken from those probes, but in the meantime, quite a few dramatic pictures were taken from Earth. Here are a few of the ones I like best… and if you want to learn more about comets, may I humbly suggest my own Ten Things You Don’t Know About Comets page when you’re done perusing these images?
Master astrophotographer Damian Peach (seriously, go check his stuff out) took this shot at 11:07 UTC on Oct. 19th. Mars is obvious enough — it’s shining at about 1st magnitude, one of the brightest objects in the sky — and the comet appears ghostly green to the lower left. Mars is very roughly 10,000 times brighter than the comet, making this a difficult observation! Right now, Mars is lined up very near the center of the Milky Way, so the background is filled with stars, providing a stunning backdrop to an already stunning image.
Did I mention how tough it is to get a shot of the pair? The Virtual Telescope Project barely captured the comet (marked with lines) at 17:00 UTC, while Mars nearly blasts out the detector (the thick vertical line through Mars is due to blooming, where the detector overflowed due to the planet being so bright). This stack of nine 60-second exposures was guided on the comet’s movement, so the stars are streaked a bit. It was taken at twilight when the duo were just 15° above the horizon, so this was challenging to say the least. The large fuzzy circles are from Mars light reflected multiple times inside the telescope.
Astronomers Nick Howes and Ron Wodaski opted to go with a wide-field image (Siding Spring is to the lower right of Mars), which really emphasizes the stars and ribbons of dust in the galaxy, hundreds of trillions of kilometers farther away than Mars and the comet. In case you needed a crushing sense of scale today.
NASA’s Wide-Field Infrared Survey Experiment (WISE) took multiple images of the comet back in July 2014. The comet’s motion is apparent as it slid between a bright star to the lower right and the galaxy NGC 1316 to the upper left. It appears red because the dust (as well as possibly carbon dioxide and carbon monoxide) released from the solid nucleus as it neared the Sun glows at the longest wavelengths WISE can see — far into the infrared, well outside what our own eyes can detect.
Of course, Hubble got in on the action as well. It took several images of the comet, and you can see activity changing the comet’s appearance over several months as ice on and beneath its surface is heated by the Sun, turns into gas, and spews out via jets.
As time goes on we’ll see more fantastic pictures of this once-in-several-million-years event, and I’ll post ‘em as I find ‘em. Check back soon!
On Oct. 16, 2014, a redditor by the handle -545- was camping at the Ashton-Wildwood County Park in Iowa. He spotted a clearing in the trees near his campsite which framed a part of the sky, so he set his camera up to take a series of 10-second exposures in the hopes of getting good footage for a time-lapse video.
What he got was better than good: He caught a bright meteor that left a persistent train, a trail of glowing vapor that lasted for quite some time:
That’s pretty amazing timing and framing. The meteor appeared right in the middle of the hole in the trees, and the meteor must have appeared very early in the 10-second exposure that first shows it; you can already see some of the vapor trail it left behind. For those keeping track at home: The brightish star to the right of the meteor is Gamma Triangulum, the star above the middle of the streak is 1 Tri, and the little diamond to the left is 12 and 13 Tri with two fainter stars (HD15226 and HD15326); it took me a while poring over my planetarium software to nail this down!
This sort of event is pretty rare, though not unheard of (I have several blog posts showing them; see Related Posts below). A meteor is just a small chunk of rock, ice, or metal that’s orbiting the Sun, and the Earth gets in its way. As it plunges through our atmosphere at high speed, it violently compresses the air ahead of it, heating it. This in turn heats the meteoroid (the solid bit of interplanetary debris; as it burns up it’s called a meteor, and if it hits the ground it’s a meteorite), which glows and leaves behind the bright but generally short-lived trail.
But the event can also ionize the air, stripping electrons from their parent molecules. As the electros recombine, they give off a bit of light. This is called a persistent train, and some have been known to last for many minutes. The train is roughly 80-100 km above the ground, and upper atmosphere winds blow it into twisting, eerie shapes.
-545- really nailed this one! You might think he was lucky, but it’s not luck. It’s persistence. Events like this happen, and if you go outside enough, watch the sky long enough, take enough pictures… you’ll wind up with something amazing.
And if you do see a bright meteor (sometimes called a fireball or bolide), make sure you note your time, location, and the direction you saw it. Then you can report it to the American Meteor Society, which collects these data. Sometimes this can help recover meteorites if there are any!
Tip o’ the Whipple Shield to reddit, and the many, many people who sent this my way.
A Meteor’s Lingering Tale
A Puff of Celestial Smoke
Like Two Trains Passing the Night… A Year Apart
A Persistent Orionid
The Remains of Halley’s Comet Burn and Linger in the Sky
On Sunday, Oct. 19, 2014, at about 18:30 UTC (14:30 Eastern), Mars will experience a very close encounter with a comet.
The comet C/2013 A1 (Siding Spring) will pass just about 130,000 km (80,000 miles) from the surface of Mars. There is no danger of an impact, but the planet will pass through part of the comet's tail (which is composed of gas molecules and dust).
NASA and other space agencies have taken precautions to make sure the spacecraft at Mars won't be hurt, but they're also hoping to capitalize on this unprecedented opportunity to see a comet VERY up close and personal. I'm not sure just when we'll start seeing data from them, but I highly recommend keeping an eye on Emily Lakdawalla's blog page and her Twitter feed. She is really great about staying up to date and relaying accurate information as soon as she has it.
I'll try to keep up as well, and if anything interesting happens I'll let you know. It's generally a good bet to follow me on Twitter too, as I'll be linking to things there, including news form other folks as it's confirmed.
A thought: The NASA comet page says the coma (the big fuzzy cloud of gas surrounding the solid nucleus of the comet) is about 20,000 km across. At closest approach, that means that if you were standing on Mars, the comet would appear to be over 8° across! That means that if you have a big hand, you could just barely block it with your upraised fist.
That's astonishing. What a view that would be! And while the astronomer part of my brain is envious and wishes we could see something like that from Earth, the human part of my brain is screaming obscenities at the astronomer part of my brain. In real life, it's probably best comets keep their distance from us.
Firefly went off the air over a decade ago now*, but even with the movie Serenity there’s been a Mal-shaped hole in the hearts of fans, including me.
Perhaps now that cavity can be filled in a little bit. The company Lootcrate, with producer and director Julian Higgins, has created a fan-made short video called “The Verse”, about a different crew in the same universe as that of the good ship Serenity. Here’s the thing: It’s really, really good. Seriously. If you’re a Browncoat, you need to watch this right now.
See? Told ya. And I’m not the only one who thinks so. Given the time span since the series ended, a reunion show seems pretty unlikely. But I could get into this new crew, I think. And hey, did I spy Vic Mignogna, who plays Jim Kirk in Star Trek Continues, another fan-made production? That must’ve been on purpose.
It’s pretty amazing what dedicated and talented fans can do. And we’re seeing more and better web series all the time, too. This Internet thing may just have a future to it.
* You kids get off my ‘verse!
After living practically my whole life on the east coast, one of the things I didn’t count on when I moved west was the lack of fireflies. They were such a ubiquitous phenomenon, such a part of the environment, that it never occurred to me that they might not be everywhere in the States.
But they don’t live in California, where I lived for seven years, or in Colorado, which I’ve called home for the better part of a decade now. I miss them.
But it helps a lot to see this lovely time-lapse (kinda) video of fireflies, shot by Vincent Brady.
Nice. And he used a clever technique for some of the effects. A video is really just a series of still images played rapidly, fooling your brain in to seeing motion. Brady took thousands of still images and strung them together to make the video. For some, he let the frames fade in, linger, then fade out again. The end result is you see the light from the fireflies persist for a few seconds before dimming, with insects at all different distances creating a stop-motion-like dance.
Incidentally, the compound that generates the light is called luciferin (Lucifer was the mythological bringer of light), which is the same class of substrate used by dinoflagellates to glow. I spent an evening kayaking on a lake filled with such protists, and watching the blue sparks fly every time I put the oar in the water was magical.
Nature is amazing. It’s wonderful what happens if you take hydrogen, helium, and a splash of lithium, and let them mix for a few billion years.
Tip of the adenosine triphosphate to Boing Boing.
The last place in the solar system you’d expect to find ice (except maybe on the Sun, duh) is Mercury. Rocky, barren, airless, and very, very hot, Mercury doesn’t sound like the ideal location for storing vast quantities of frozen water.
But in the 1990s evidence started coming in that perhaps Mercury was holding a surprise. At its north pole are deep craters, and because of their high latitude, the low Sun never reaches the crater floors. They’re permanently dark, and because of that they’re very cold. Cold enough to hold on to any water that might have found its way there (presumably through water-bearing asteroid and comet impacts).
The first evidence was from radar observations; those craters were found to be very radar-reflective, which suggested ice, though other materials were possible. But over the years more clues arrived, and when the MESSENGER spacecraft began orbiting the tiny world, the idea of polar water got kick-started. Neutrons were reflected from the crater floors, which indicated the presence of hydrogen (water molecules have two hydrogen atoms each and are very good at reflecting incoming neutrons). MESSENGER has an infrared laser altimeter on board (it uses timing of pulses of light to measure its height off the surface and get topological data), and the craters were again found to be very reflective, which is consistent with ice.
And now we have further, very striking data: Pictures taken of the floor of the crater Prokofiev* show that some of the surface itself is a bit brighter, a bit shinier, than surrounding material. Not only that, but the brighter regions correspond extremely well with what has been found before.
The picture here shows the data. The upper left (A) is from radar observations; the blue circle is the crater rim, the red region is where it’s permanently shadowed—the Sun never shines there—and the yellow is where the radar reflections were brighter than normal. The bottom left (B) shows where the laser altimeter found unusually bright material. On the right (C and D) are the images taken by MESSENGER’s visible light camera. They are the same area and have the same orientation but were taken when the Sun was shining from different directions. The brighter landscape there is clearly visible on the right, and as you can see matches the other observations right on the nose.
The scientists found similar results in other craters even farther north on Mercury (Prokofiev is about 5° south of the north pole, and is 112 kilometers, or 70 miles, across). The amount of ice estimated to be trapped in the floors of these craters is 10 billion to one trillion tons—a huge amount. As the paper points out, that’s about the volume of Lake Ontario.
Personally, I find this to be pretty convincing. It's not a 100 percent lock, but the evidence is getting to be pretty hard to deny.
The ice is likely to be young, too. Impacts, ultraviolet light breaking down the molecules, and other weathering could darken, bury, or eradicate the ice on a timescale of tens or hundreds of millions of years, so it’s likely this deposit hasn’t been around since the early solar system (astronomers define "young" differently than normal humans).
In practical terms, I have a hard time seeing us sending folks to Mercury, setting up a base at its poles, and taking long hot baths using native water any time soon. But this shows that even now, with our huge telescopes, advanced hardware, and robot probes peeking and poking into every corner of the solar system, there’s still a lot to learn about our neighborhood, and a whole lot of surprises waiting to be unwrapped.
We also have similar evidence of water at the Moon’s poles, too, buried under and mixed into the rock at the floors of eternally darkened craters. I don’t have a hard time seeing us going there at all. There could be enough water on the Moon to support a colony for quite some time. That is something I would very dearly love to know more about.
*Craters on Mercury are named after artists: composers, painters, writers, and so on. Sergei Prokofiev was a Russian romantic composer, and one of my favorites; his Fifth Symphony is an astonishing work. It pleases me that such an important discovery has been found in his namesake.
In July of 2015, the New Horizons space probe will whiz past Pluto, traveling at 40,000 kilometers per hour. For several weeks before and after the close flyby — it’ll pass within 10,000 km above the tiny world’s surface — it will examine Pluto, its moons, and the environment around it.
But this is not an orbiter, or a lander. Pluto is 5 billion kilometers from Earth, and the only way to get a probe there in any decent amount of time was to strip it down as light as possible and fling it as hard as possible, getting it moving so rapidly it could traverse the yawning chasm between us and Pluto as quickly as possible (with a boost from Jupiter along the way).
This is a fast flyby, with no slowing down. Once New Horizons is gone, it’s gone.
Except the solar system hardly ends at Pluto. There’s a vast collection of objects out there in the dark: cold, icy wordlets called Kuiper Belt Objects. There are millions of them, relics from the formation of the solar system itself, and largely unchanged for billions of years. Getting a look at one up close is a very tempting goal.
The New Horizons team started a search in 2011 using large ground-based telescopes, and while they found dozens of these KBOs, none was near enough the probe’s trajectory to investigate. Remember, space is vast and empty — that’s why we call it “space” — and while there may be millions of KBOs, they’re still spread pretty thin out there.
So they turned to Hubble. Narrowing the search but able to detect fainter objects, Hubble was the last hope… and it paid off. They found three potential targets, each over a billion kilometers farther out than Pluto. One, called (for now) PT1 (guess why) should be easy to reach given New Horizons’ present path and fuel supply. Its size is not clear, but based on its brightness and likely surface reflectivity it’s probably more than 30 km (20 miles) in diameter. New Horizons would fly past it in January 2019.
Not that this is a given. Ostensibly, the probe’s mission is over once it flies past Pluto. The team will have to ask NASA for an extension, and those aren’t given out lightly. However, I think this is a very worthy goal. We’ve never seen a pristine KBO up close, just moons we think used to be KBOs but were captured by planets, like Neptune’s Triton and Saturn’s Phoebe. These are likely to have changed over time since they became enthralled to their parent planets, so finding a KBO in its natural habitat is a very exciting idea.
Also, politically, I think it’s a feather in NASA’s cap to be able to retool a space mission to do something more than it was originally designed to do. If things go well at Pluto, and we expect they will, the public will be pretty excited about the mission; folks seem to have a special place in their hearts for the little iceball. Leveraging that would be pretty smart on NASA’s part.
For details on the search and how they planned this flyby of a KBO, go read Emily Lakdawalla’s writeup. She has (as usual) an excellent and very thorough article about it.
I’m excited about this. I’ve been interested in KBOs since my own days with Hubble; I spent a little bit of time looking into using Hubble to search for objects very far from the Sun, and unfortunately given the logistics at the time (back in the late 1990s) it wouldn’t have really worked. But the cameras are better now, our techniques have improved, and it’s really gratifying to see this getting done. And if PT1 does rate a flyby, we’ll see that little blip in the Hubble image turn into a place, a small but perfect example of what our solar system is like, in the far reaches of nearly — but not quite — empty space.
Here at BA Central, we’re* big supporters of evidence-based reality and using science as a way to collect and weigh that evidence.
The problem is that a lot of science isn’t well understood by the public for a large number of reasons; some folks blame the education system, which certainly has issues, though perhaps a much larger and more endemic problem is ideology, which gets into your brain and acts like a bouncer at a bar, only letting through ideas that are on a preconceived checklist.
Evolution is an obvious example. Despite being one of the fundamental bases for all of modern biology (along with things like molecular biology, genetics, and so on), it is routinely and falsely attacked by many. A lot of scientists and science communicators scratch their heads over that; what’s hard for us on this side of reality to understand is how anyone can ignore the vast mountains of evidence supporting evolution.
My friend Zach Weiner put his finger right on it, in my opinion, when he wrote this:
I think that’s it; the folks who don’t “believe” in evolution are the ones disseminating a weird, wrong, strawman version of it.
While there’s not a huge amount I can do about that, what I can do is try to make correct, easy-to-understand information about evolution available. I’ve done it before and it seemed to work out well.
So I’m pleased to send y’all to a great website called “Stated Clearly,” where artist and science communicator Jon Perry has created a series of wonderful videos where information about and evidence for evolution is, well, stated clearly.
The video “What Is the Evidence for Evolution?” is fantastic. It’s simple without being oversimplified, and it gives clear examples that can be followed easily even if you’re not all that familiar with the science.
That last part is critical, because, as Zach pointed out, the ones fighting tooth and nail against evolution are almost assuredly not that familiar with it. If they were, we wouldn’t be spending our time defending evolution. We’d be spending more money investigating it.
Perry has assembled quite a team to create these videos (including, I was pleased to see, Rosemary Mosco, a field naturalist, science communicator, and friend-of-a-friend). There are articles there as well expounding further on some of the themes.
The evidence video was sponsored wholly through Kickstarter, which is great, since it costs a fair bit to put together something like this. If you have any extra filthy lucre lying around, you should consider throwing it their way. They’ll have merchandise soon, and I’ll be keeping an eye out for that. I want a shirt of Darwin riding an Archaeopteryx.
Tip o’ the telomere to Raw Story.
Once again this year I have talked the talk and walked the walk: I got my annual flu shot.
I was hoping you’d see more of my asteroid tattoo in this picture, but what the heck. It gets the job done. As usual, the shot was painless, inexpensive, and should help my immune system do what it’s meant to do.
Flu shots are important. Everybody’s freaking out about Ebola right now, but every year the flu kills far more people! By getting my shot, I’m doing two things: teaching my immune system how to fight off the influenza virus likely to be common this season, and also keeping me from becoming an unwitting host to the virus, able to infect others.
That’s critical. For me personally, if I get the flu the odds are I’ll be miserable for a few days and more whiny than usual. But my wife is immunocompromised, and if she gets a full-blown infection the complications could be very serious. That’s why we get our immunizations every year. It helps build herd immunity, and that protects people who cannot get the shot and could get critically ill from the flu.
Sure, Ebola is scary, but it’s made far scarier by the media in this country that is have their priorities grossly out of whack. Given how communicable influenza is, and how dangerous it is, they’re spending way too much telling you about the wrong virus.
And that’s not even including measles, pertussis, and more diseases that are making strong comebacks thanks largely to the anti-vaccination movement. But I’ve already been pretty clear how I feel about that.
Go talk to your board-certified and find out what’s best for you. And if they recommend it, go get yourself vaccinated.
And before you ask about the t-shirt I was wearing... did you see yesterday's post?
Holy Periodic Comet Photos! Check. This. Out!
That is a self-portrait taken by the Philae landing craft onboard the Rosetta space probe, when they were just 16 kilometers (10 miles) from the comet 67P/Churyumov–Gerasimenko. You can see the side of Rosetta on the left and the solar panel that’s keeping it powered on the right.
And at the top is the comet itself, magnificent and moody in this high-contrast grayscale composite (two images were combined so that both the spacecraft and comet were exposed well). You can even see a jet emanating from the comet, a stream of gas blown out as ice is hit and warmed by sunlight. Stunning.
Rosetta is nosing closer to the comet, and will release the Philae lander in a few weeks. On Nov. 12, the probe will touch down on the surface of the comet, a milestone in our exploration of space. Judging from the quality of this picture, what we will see on that day will be jaw-dropping.
A little while back I posted an amazing Vine video taken by an astronaut on the International Space Station. It shows the release of the Cygnus cargo resupply ship Janice Voss, which had finished its mission bringing supplies up to the ISS. It was filled with trash, unberthed using the robotic CANADARM 2, then put into an orbit that would drop it into Earth’s atmosphere to burn up over the Pacific Ocean.
In the video, the Voss looks like it goes up, into a higher orbit than the ISS, which I thought might be due to the use of a wide-angle fisheye lens. I also supposed it might be due to the orbit of the ship. Watch the video:
So, what’s going on? I got an email from someone who knows orbital mechanics (but prefers to remain anonymous), and he confirmed my suspicions. To explain, I need to give you a brief intro to orbital mechanics. It’s not like the movies … and let me note that I’m no expert in orbital mechanics, so if I make an error here it’s mine, and not my source’s. I’m also going to leave out some details that are a bit hairy, but if you like, you can read up on how orbital mechanics works. It’s pretty cool.
When an object is in orbit around the Earth, its velocity is dependent on how far it is from the center of the Earth (the orbital radius) and the shape of its orbit. For a circular orbit, the orbital radius doesn’t change, so the velocity is constant. If you increase the radius (its distance from Earth) the velocity slows down, so a circular orbit with a larger size means the spacecraft orbits more slowly.
If you want to get to a higher orbital radius, you point your spacecraft into the direction it’s heading and ignite the rocket. The thrust adds velocity to spacecraft for a short time. But that doesn’t put it in a bigger circular orbit; the added energy stretches out the orbit, making it elliptical. The highest point of this new orbit (called apogee) is above the old circular orbit, and the lowest point (perigee) just meets the old one (the old-fashioned term for this is “osculating,” which means “kissing,” a delightful use of the word).
So what does this mean for the ISS and Voss? They start off moving at the same speed, because they’re connected. Voss faces forward, disconnects, and ignites its thruster. The added energy puts it on an elliptical orbit, and it immediately goes up into a higher orbit than ISS; that’s what we see in the video, and why Voss appears to move away from Earth. That’s because it does move away!
Now, if that’s all there was to it, one orbit later Voss and ISS would meet up once again when Voss reaches perigee. But we don’t want that! The whole point is get the spacecraft away from the ISS. So how did they do that?
Watch the video again. Just before the burn, Voss dips its nose a little bit, pointing it slightly down toward the Earth. So it wasn’t thrusting exactly tangent to its orbit; the rocket pushed it down a bit. That maneuver also affects the shape of the elliptical orbit, changing where Voss will reach perigee, and also dropping perigee a bit lower. One orbit later, when Voss reaches perigee, it will be ahead of and lower than ISS. That prevents any chance of collision, even if the spacecraft loses power; the orbits no longer cross.
That would be the situation forever if nothing changed. However, the endgame here is to drop Voss into Earth’s atmosphere. So, a couple of days later, after engineers made sure everything was kosher, they made a final maneuver. They turn Voss around, so now it’s facing backwards in its orbit (tail first). The rocket is fired again, which drops the apogee of the orbit to inside that of ISS, again preventing a collision. The perigee also drops, and the burn lasts long enough so that at perigee the Voss is inside Earth’s atmosphere.
Half an orbit later Voss reaches perigee, and Earth’s air now has a large drag effect. It steals energy from the orbit, dropping the spacecraft even lower. At that point, atmospheric drag really takes over, and you get the spectacular fireball as the ship hypersonically rams the air in front of it, compressing it, and heating it up hugely. The ship becomes a human-made meteor, and falls into the ocean (where, I suppose, it becomes a human-made meteorite).
I find orbital mechanics fascinating, because it all works following (relatively simple) rules that only seem counterintuitive (I had the devil’s own time understanding this video until I realized the Voss was on an elliptical orbit; the mechanics suddenly became way easier to understand). That’s OK, as long as you don’t fret over the instincts humans have developed over millions of years living on the ground.
Flying into space we put centuries of math to the test … and it works. It works. That to me is one of the most amazing things about science that there is: The Universe obeys a set of rules, and we can figure them out. And in many cases, we truly have.
File this under “Too Ironic to Describe Without Making Your Head Asplode”:
Briefly, Sally Morgan is a self-proclaimed “psychic” who says she can to talk to the dead, and so on. However, reports on her readings make me extremely skeptical of them, as they sound an awful lot like cold reading. She sells out theaters, charging a fairly healthy sum for tickets (as well as for telephone readings).
Recently, a British skeptic named Mark Tilbrook handed out fliers outside some of Morgan’s shows, simply asking people to think about her methods critically. He never says she’s a faker, fraud, scammer, or anything like that; the wording is polite and matter-of-fact.
After doing this at a few shows, Tilbrook was accosted by Morgan’s husband and son. They threatened Tilbrook physically, made death threats, and used homophobic slurs in their confrontation. There’s video of the whole thing.
Since that went public over the weekend, Morgan has had to go on the defensive (and the offensive, claiming Tilbrook has "targeted" her, though by his own account his actions have not been pushy). She’s made a public statement on her site, saying she has “sacked” her husband and son, who no longer will hold the positions of personal manager and tour manager, respectively. In the statement she apparently doesn't perceive any self-imposed irony, saying:I have come from a family background that has always been very accepting, many of my friends are gay and I have always felt happy that I am often referred to as a gay icon through my work. I am utterly ashamed and devastated at the behaviour of my husband John and Son in Law Daren and neither of them will have anything to do with my work, my business and right now I honestly have no idea what is going to happen to my marriage.
If she really doesn’t know what the future holds for her, maybe she should consult a psychic.
… but none quite like this: The eclipse was observed by the MESSENGER space probe, all the way from Mercury! Normally MESSENGER looks straight down on the tiny world, mapping the terrain that slides underneath it. But engineers saw an opportunity for something neat, so they pointed the camera toward Earth and took 31 images, each two minutes apart, to capture the dance of light:
It’s not often something makes me laugh in delight, but that grainy, lumpy video did. You can see the Earth on the left, all of five pixels wide in the original images (the entire video has been expanded by a factor of 2), and the Moon on the right, just barely bigger than a single pixel. The motion of the Moon is too small to detect, but as it passes into Earth’s shadow it dims considerably, disappearing.
Even then, the brightness of the Moon has been multiplied by 25 to make the change more obvious. On Oct.8, during the eclipse, Mercury was nearly between the Earth and Sun, so to MESSENGER, the Earth and Moon were close to full. But the Earth is bigger and more reflective than the Moon, and would look 50 or so times brighter. I’m not surprised they had to enhance the Moon’s brightness.
MESSENGER was 107 million km (66 million miles) from Earth when it took these images. I think that may be a world universal record for the most distant (terrestrial) lunar eclipse ever seen.
Tip o’ the umbra to Emily Lakdawalla.
The sheer scale of space is overwhelming. Oh, sure, we have words to make it more palatable, like “light years” — as if a distance of 10 trillion kilometers is graspable by our puny simian brains.
And when I think about our galaxy, the Milky Way, I know that it’s 100,000 light years across, but that’s just a number, the reality too huge to truly hold in my mind.
But what really gets to me is how many stars are in the galaxy. Astronomers, including me, offhandedly say it has something like 200 billion stars comprising its bulk. 200 billion. Written out, that’s
And I look at that, and my brain parses it, dissects it, counts the zeroes, makes analogies, uses scientific notation… all in an attempt to grasp the ungraspable.
So how many stars is that, really? Here, this might help. Or it might crush your brain further.
That is a mosaic of 50 separate images of the galactic center taken by astrophotographer Robert Gendler. It’s a stunning 60 hour total exposure using a small but extremely high-quality telescope, and shows a stunning number of stars and other objects. As I perused it I saw a lot of familiar sights, including the pink glows of the Lagoon and Trifid Nebulae on the right, and the Cats Paw Nebula to the left of NGC 6357, both in the lower left.
And while those are beautiful, it’s the stars that I keep coming back to. So many stars… and not just the bright blue stars to the left, which are naked eye visible, and belong to the stinger in the tail of Scorpius. No, I mean the fainter ones, the anonymous ones dense as sand on the beach in the image. It’s actually it’s hard to see them; I shrank the photo to 1440 pixels wide to fit the blog. Here’s a section of the upper left part of the image taken from a larger (5000 x 3329) version:
Holy stelliferous nights! Now you’re starting to get a glimpse of what I mean. You can see tens of thousands of individual stars, perhaps more. And even that is nothing. When you look at the whole photo, all of the yellowish glow, all of it, is actually coming from stars. That’s not gas, or dust; it’s the combined light coming from billions of stars, all too far away to resolve as individuals. In fact, the dark areas aren't where there are no stars, they're where dust clouds block our view of even more stars behind them!
And this is still just a small section of our galaxy. While the image shows a big chunk of sky, roughly 30° across, the Milky Way is still far, far larger.
And that’s when I can’t do it any more. The numbers I understand, but the reality of them is too huge.
When I was a kid — this is true — I used to look up at the sky and fear that some day we’d explore everything, and run out of things to discover.
I was completely wrong. We’ll never run out of sky. Just look at it.
And while it may make some people feel small and insignificant, I get exactly the opposite feeling: That we can even attempt to understand all this — and that, in so many ways, we actually do — makes us big indeed.
I have been known, over the course of the past few years, to post pictures of the odd cloud or two. And I do mean odd. Sometimes they’re photos I’ve taken myself (and some of which have been very difficult to identify), sometimes they’re from machines in space, and sometimes from humans in space.
Still, I’m not a cloud chaser per se; you won’t see me hopping in my car and driving hundreds of kilometers to spy a weird cloud formation someone tweeted about, for example. On the other hand, if someone were to tell me they saw something like this nearby, well, I’d think pretty hard about getting my car keys and going for a look-see.
Those are undulatus asperatus (agitated or turbulent wave) clouds, a type of cloud that is starting to get consideration as a wholly new category. From what I can tell, they are formed when there’s rising air that creates wide-spread cloud cover, together with wind shear that blows across the rising air. This can set up gravity waves, where air moves up and down as buoyancy and gravity battle it out, creating long rippling waves that carry the clouds up and down.
You can find out more about this on Slate’s Atlas Obscura blog. I urge everyone to bookmark that blog; it is always a fascinating tour of the weirder and wonderfuller places on our planet.
And let me leave you with this simply jaw-dropping video of undulatus asperatus in action. Make it high-def and full screen, because seriously: Holy wow.
Two tremendous storms* are heading for landfall on the other side of the world from the US. Both are phenomenally dangerous… yet both are exquisitely beautiful when seen from space.
That is Supertyphoon Vongfong, which is in the Philippine Sea, and on course to hit southern Japan. It’s a Category 5, with wind speeds measured on Oct. 9 as 145 knots (nearly 270 kph). It may weaken slightly before hitting landfall, which would be nice for the people in its path. On Oct. 7, the NASA TRMM satellite measured rainfall near the eyewall of about 10 cm/hr (4 inches/hr).
That image was taken by NASA’s Aqua satellite, designed to study the water cycle of our planet.
That shot of the eye is amazing. Given the perspective (how close the eye is to the limb of the Earth) I’d guess the eye was well over 1000 km away when he took this picture, perhaps even twice that. He used a wide angle lens, so it’s difficult to be sure. Either way, this shows just how huge this typhoon is.
The other storm is Cyclone Hudhud, currently predicted to make landfall in India on Saturday or Sunday local time:
That Aqua image was taken on Oct. 9. Although not as well organized as Vongfong, it’s still a Category 4 storm, and is expected to hit a heavily populated region of India. After a devastating storm landfall in 1999, India is better prepared to deal with this type of event. You can read more about it in my colleague Eric Holthaus’s article on Slate.
I’ve been through enough big hurricanes to know how terrifying they can be, and how much devastation they can deal out. It’s jarring and disturbing that the bringers of such terror can be so pleasing to the eye from space.
Distance can bring perspective, but in this case both the beauty and the dread are things worth bearing in mind.
It’s also worth remembering that it’s satellite images (along with data from others like TRMM) that allow scientists to make better predictions of where these monster storms will hit, and how much damage they can bring. The people working on this are saving lives, and billions of dollars. That’s what science can do.
* The general term for storms like these changes depending on location. The NOAA has the best definition I’ve seen:Hurricanes, cyclones, and typhoons are all the same weather phenomenon; we just use different names for these storms in different places. In the Atlantic and Northeast Pacific, the term “hurricane” is used. The same type of disturbance in the Northwest Pacific is called a “typhoon” and “cyclones” occur in the South Pacific and Indian Ocean.
Vongfong is in the Northwest Pacific, so it’s a Typhoon, while Hudhud is in the Bay of Bengal/Indian Ocean, so it’s a cyclone.
There are approximately eleventy bazillion pictures of the recent lunar eclipse on the web right now, but a few in particular struck me, and I love to share.
The first is from Teoh Hui Chieh (who took one of the most amazing videos of last year’s annular solar eclipse I’ve ever seen). For the lunar eclipse she was in New South Wales, Australia, and took this phenomenal shot of the eclipsed Moon over one of the dishes of the Australia Telescope Compact Array:
That’s the Moon above and to the right of the antenna. You don’t normally see the full Moon and Milky Way at the same time! The bright moonlight usually washes out the much fainter glow of our galaxy. But during the eclipse the Earth’s shadow diminished the Moon’s fierce glow, allowing this dramatic shot.
You can see more of her amazing work at her website, My Dark Sky.
Another amazing astrophotographer, Rogelio Bernal Andreo (and oh do I love his work) decided to go a different route. He took a short exposure of the Moon to get the light balance right, and then a deeper exposure to show the stars behind it. Compositing them created this lovely scene:
The arrow points to the planet Uranus, which hovers just around the edge of naked-eye visibility. Its bluish color is real, due to methane in its atmosphere that absorbs red light, letting blue light reflect back toward us.
Run, do not walk, to his site, Deep Sky Colors, and set your brain for “stunned”.
Of course, hoaxes pervade the Internet. This one is making the rounds again, claiming it’s taken from the space station:
That’s actually a drawing, and a lovely one as well. But it’s not an actual picture taken from space. I wrote about this before; it’s by A4size-ska on DeviantArt. Click that to see the original; it’s really well done. But take it for what it is: a sensational piece of artwork, not a photo from space.
Finally, what did the Earth look like from space during the eclipse? The Suomi NPP Earth-observing satellite has a detector on it that can see very faint light on Earth. It passed over the US every 90 during the eclipse, imaging a broad swath of the planet as it did. Between orbits, different amounts of the Moon were in the Earth’s shadow, providing different amounts of illumination on our planet. Christopher Kyba put those observations together into this unusual portrait of Earth during the eclipse:
That’s really cool. I love looking at familiar sights in different ways, and this is an exemplar of that.
Lunar eclipses are amazing. If you want to see more pictures, try UniverseToday, where there’s a nice gallery.
I can’t believe that right now, more than 10% of the way into the 21st century, I have to write these words, but here we are:
Astrology doesn’t work.
It really is that simple. I need not go into detail here; I’ve already said what I have to say showing exactly why astrology is wrong; astrologers fail to show there’s any evidence that astrology works even when the tests were devised by astrologers themselves! Astrology has no predictive power, no physical cause to believe it has predictive power, and is entirely explained by psychological effects like confirmation bias (remembering predictions that were right and forgetting the ones that were wrong) and the Forer effect (thinking vague, general predictions apply to you specifically).
Yet astrology still gets far, far more attention than it deserves. Just yesterday, I was appalled to find out that Time magazine posted a credulous puff-piece interview with an astrologer. Just as bad, it was focused on the astrology of the lunar eclipse on Oct. 8.
That’s really galling to me. To take a beautiful and wondrous astronomical event and hang this sort of pseudoscience on it is like spray-painting the wall of the Grand Canyon. It’s defacement.
The Time interview is filled with the standard kinds of vaguely worded claims used by astrologers, like eclipses “end something and they brings [sic] something else. But it really needed to end… There’s a shock factor first, and then a solution that turns out to be so good that you realize, wait a minute, this is a blessing.”
First, lunar eclipses are world-wide events; everybody on the side of the Earth facing the Moon could see it. How could this astrological attribute possibly apply to every single person? Second, note how vague the statement is. The beauty of it (if you’re an astrologer) is that, ironically, anyone who had anything come to a close in their life — from breaking up with a lover to finishing watching a TV series — could apply it to what they experienced. A prediction that general has no real power of prediction at all.
It goes on and on like that. The worst part is there is no hint of skepticism, no actual investigating, that might show that astrology is nonsense. The story here isn’t that astrology is wrong, it’s that Time magazine would give it any sort of support at all.
I'll note that the article's writer did a second interview with Miller that went up the next day, saying why she doesn't think now is the right time to buy an iPhone 6. Before even reading it, I muttered, "Let me guess. Mercury is in retrograde." Yeah, guess what:“I’m such an Apple addict, I love everything they come out with, but it’s not the right time,” Miller, founder of Astrology Zone, tells TIME. “I know that everybody wants to buy the iPhone 6, but you’ve got to wait.” Why? Mercury is in retrograde between October 4 and 25 — and that period of cosmic slowing, when the planet appears to be traveling backwards, is notorious for misunderstandings and technological failings.
Sigh. Mercury in retrograde affecting electronics is another slice of astrological folderol.
Look. As I’ve said many times before, it’s not that astrology, as a specific flavor of anti-science, is doing direct damage to anyone — except for separating people from their money.
The real problem is that, like all manners of nonsense, it erodes away our ability to separate what’s real and what isn’t. Today, more than ever before in human history, that ability is crucial for our survival. We have concerted, well-organized, and heavily funded efforts underway to demolish that ability, from global warming deniers to anti-vaxxers to politicians who want to control your body and your wallet.
They don’t need the help, especially not from major media outlets like Time magazine.
And, as always, remember:
Tip o' the Ouija board to Mark Wilkins.
Did you see the eclipse last night? Pictures are rolling in on Twitter and Facebook, and they're lovely.
But the night before, on Oct. 7, astrophotographer Steve Knight caught a different kind of eclipse: The International Space Station passing in front of the Moon. He even got video of it:
Cool! He slowed the video down by a factor of 10; the event only lasted 1.3 seconds. To be fair, this is technically called a "transit," when something smaller passes in front of something bigger, and not an eclipse, when the objects are closer in size. But the timing of it was too close to not have fun with it.
Last night, right after the full Moon rose a few hours before the lunar eclipse started, I happened to go outside to check something in my front yard. I looked up (because I always look up) and by coincidence happened to see the space station passing through the sky! It was very bright, and its path took it almost directly overhead. As it moved silently across the sky, I glanced over to the Moon, just a few degrees above the eastern horizon, and then at the Rocky Mountains, to my west. The sparse snow on the tops of a few of the mountains was dimly lit by the Moon, and I realized how magnificent the view from ISS must have been: the Moon to one side, the mountains below. I hope at some point I'll see photos of that.