Bad Astronomy Blog
Today is the real reason for the season: It’s the winter solstice! If you’re a purist, then raise your glass at 23:03 UTC (18:03 Eastern US time), because that's the moment the solstice occurs.
There are a lot of ways to look at this, but they all boil down to the Earth’s axis being tilted with respect to its orbit. You’ve seen this with classroom globes; they’re tipped by about 23.5°. As it orbits the Sun, the north pole of the Earth’s axis is always pointed pretty close to Polaris in the sky, which means that sometimes the axis is tipped toward the Sun, sometimes away. When it’s tipped as far from the Sun as it can be, that’s the moment of the winter solstice.
Illustration by Tfr000 on wikipedia, Creative Commons License. In this animation, the winter solstice occurs when the Earth is to the far left part of its orbit, and the northern axis points away from the Sun.
Of course, when the northern pole is tipped away the Sun, the southern pole is tipped toward it, so it’s summer down there. In that sense, it’s better to call today the “December solstice” rather than “winter solstice”. Nearly 900 million people live south of the Equator, so it’s probably a good idea to keep them in mind when we name things.
But for us in the north, today is the day the Sun stands still (the literal meaning of “solstice”). What does that mean? If you go outside every day at local midday (literally, halfway between sunrise and sunset) and note the position of the Sun in the sky, it changes during the year. It’s lower in the winter and higher in the summer.
Today is the day it gets as low as it can at midday—that’s why it “stands still”; it’s dipped as low as it can go and has stopped its decline. It’s the shortest day and longest night of the year. If you go out tomorrow it will be a wee bit higher at midday, and the day will be a tad longer.
The change is slow at first, then speeds up, accelerating the most at the vernal equinox in March. On that day, the days are lengthening as quickly as they can, usually by a couple of minutes or so per day. Then, at the June solstice, the Sun is as high in the sky as it can get, days are at their maximum length, and the Sun stands still once again. It reverses course, and starts getting lower every day at midday until late December.
Lather, rinse, repeat. Unless you're in the southern hemisphere, where this is all upside-down, so for you austral folks: repeat, rinse, lather.
And this is why we have seasons: In the summer the Sun gets higher in the sky, heating us more efficiently, and the day is longer, so there's more time to warm up. In the winter it's lower, and the days are shorter, so it gets cold.
Some people call today the first day of winter, but I prefer to think of it as mid-winter’s day. After all, today the Sun starts getting higher in the sky, so why say that’s the first day of winter? Weather is regional, anyway, so trying to tag a definition of when winter starts is pretty silly.
Instead, use today to think about astronomy, cycles, the motion of the Earth, the patterns of the sky, and the amazing nature of our Universe.
Or, honestly, why not every day?
Years ago, when the first transiting exoplanet (HD 209458b) was found, I was startled to realize that it could be easily detected using a small, inexpensive telescope.
Transiting exoplanets are planets that orbit other stars, and from Earth we just so happen to see their orbit edge-on. That means it passes in front of their parent star (that’s the transit bit), blocking a fraction of its light. A tiny fraction, usually far less than 1%. But if the star is bright this dip in brightness can be spotted in small telescopes. I remember doing the calculations and finding that a 30 cm telescope could detect HD 209458b in a single night’s observations. Tough, but possible.
That meant an amateur astronomer could detect exoplanets! What didn’t occur to me at the time is that you don’t necessarily need a telescope to do so.
David Schneider, an editor at IEEE Spectrum, has described a setup using a digital camera and 300mm telephoto lens that has allowed him to detect the transit of the exoplanet HD 189733b, a so-called hot Jupiter, a massive planet orbiting very close to its star. The transit depth is about 2.6%, and his data look pretty good to me. He based his work on an amateur astronomer (vmsguy on the Cloudy Nights forum) who has also posted data that look pretty convincing.
Basically, the idea is to take several exposures over the course of the transit, taking care to make sure you get pictures taken before and after the transit. That’s your baseline. Using software to align the images and examine the stars (both vmsguy and Schneider used IRIS, which is Windows only, but other packages exist), you measure the brightness of the star over time to see the transit.
Not that it’s that easy! In reality you do relative photometry: You measure the brightness of many stars at the same time, so that a passing cloud doesn’t dim your star and make you think you’ve found an exoplanet. You also have to take other calibrations (like darks and flats), and apply them carefully. But it’s not impossible, and in fact sounds like fun.
Mind you, Schneider went all-in, even to the point of building his own gear to track the stars; but if you have a telescope you can always just use the motor drive that does that for you. The point is, you can detect exoplanets using just a camera, a good long lens, and a solid mount!
That’s amazing. I’ve been thinking of trying this sometime using my own 20 cm ‘scope; a lot of exoplanets are within range. But I’m still figuring out how to take astrophotographs, and believe me, I know how addicting this can be. I used to do this for a living, and if I get the software and start observing, I’ll be down the rabbit hole pretty quickly!
But in some ways, that’s the point. If you have the time and resources, it’s pretty amazing what you can do. You can even observe alien worlds.
Tip o’ the lens cap to James Walker.
Well folks, looks like I have your next desktop wallpaper for you: a Spitzer Space Telescope image of the incredible Flame Nebula, a star-forming gas cloud hanging off Orion’s belt:
Spitzer is an infrared telescope, sensitive to light well beyond what our eyes can see. When it comes to astronomical objects, this part of the spectrum is dominated by the glow of dust—long, carbon-based molecules created when stars are born and when they die. Chemically, the dust is a polycyclic aromatic hydrocarbon, and is pretty similar to soot.
That makes it dark in the kind of light we see, but when it’s warmed by nearby stars it glows in the far infrared, where Spitzer can see it. The Flame Nebula is a cloud of gas and dust roughly 1,000–1,500 light-years away, and in visible light it glows due to the flood of ultraviolet light from Alnitak, the easternmost star in Orion’s belt (seen in the Spitzer image as the bright blue star in the upper center); this UV energizes hydrogen, oxygen, nitrogen, and more, causing them to glow.
But in this view we see the dust, warmed by NGC 2024, a cluster of newborn stars in the Flame’s heart. The stars blast out fierce winds of subatomic particles—called stellar winds—as well as lots of UV light, which carves out a huge cavity in the middle of the cloud. You can actually get a pretty good sense of that growing hole in the Spitzer image.
But there’s more: On the right, you can see the ghostly outline of what looks like a horse’s head poking up above that shelf of dust stretching out horizontally. This actually is the amazing Horsehead Nebula, so named for its appearance in visible light:
How about that? The Horsehead is also the site of star birth; the bright star at the top of the head (appearing red) is a newborn star that’s deeply embedded in dust. Just off the top of the picture is the bright star Sigma Orionis, actually a five-star system that is incredibly bright and powerful. The light from that star is so intense it’s eating away at the top of the nebula, and you can see this as a bright rim along the top of the Horsehead in the Spitzer image. An infrared image released by Hubble in 2013 shows this more clearly, too.
What an amazing shot. And be careful not to confuse this picture with one of the more famous Orion Nebula! They do look similar, and are actually fairly close to each other both in the sky and in our galaxy.
I love that such beauty is actually so scientifically interesting, as well as so fundamentally important, as well: Places like this are where a lot of stars in the Universe are born. Our own Sun may have formed in such a cloud, billions of years ago.
If you’re looking for wonder and amazement laced heavily with eye candy, astronomy is a pretty good place to find it.
Promoting science can be tricky. In general it’s fun and rewarding. I have a passion for science, and I wear it happily for all to see.
But there are minefields afoot. Of course there are people who deny science, and they will let the vitriol flow if you happen to stick a toe into their territory. There’s also the issue of diversity, including topics like women in science as well as people of different backgrounds, color, beliefs, and so on. I’m all for promoting more inclusion in science: the more the merrier! Reality is and should be for everyone.
But how to do this, how to actually promote these ideas, can get interesting.
The picture is titled “Actresses with a passion for science” and shows five such women: Hedy Lamarr, Lisa Kudrow, Mayim Bialik, Natalie Portman, and Danica McKellar. I know how important it is to have good role models for kids, and how girls need more support in getting into STEM (Science, Technology, Engineering, and Math) fields. Like it or not, actors and other famous people bear weight, so showing famous actresses who love STEM in my opinion is a pretty good thing.
So I retweeted the picture, adding “Love this” to it.
Then things got interesting.
Within minutes I started seeing responses about Dr. Bialik. Yes, “doctor”; she has a PhD in neuroscience. The thing is, she also holds a number of beliefs with which I and many others disagree, some of them very strongly. For example, she’s a spokesperson for a group called Holistic Moms—they support homeopathy, a provably worthless and arguably dangerous bit of “alternative medicine”. They are also strongly anti-vaccination, and Bialik herself supports anti-vaxxers (she has stated she has not vaccinated her own children, a position I am strongly opposed to).
I knew all this when I retweeted the picture. I’ll admit, I hesitated before doing so, specifically because of this. Is promoting this picture also promoting anti-science beliefs? Looking at the responses on Twitter, a lot of people think so. I see their point, but I also don’t think this is quite so black-and-white.
I do strongly disagree with many of Bialik’s beliefs. But I also know that she is a high-profile actress, starring in “The Big Bang Theory” where she plays a scientist. Her character, Amy Farrah Fowler, is a biologist and is commonly seen doing work in the lab and talking about her research with her friends. I’m quite fond of her character; she’s a passionate scientist, a decent person, a dork, emotional, analytical, and has trouble being objective when assessing her relationship with her significant other. I know a lot of people like that. I am people like that.
Clearly, she can be a positive role model for science. However, we must have a care. The same people who might be inspired by her pro-science message might look into her more and find that she holds some less-supported beliefs, some that are anti-science.
So is using her in that montage of pictures a good thing or a bad thing? I would argue it’s neither, but the good outweighs the bad. The facts are that she is a scientist, she is an actress, and the picture was about actresses who are scientists. In point of fact, celebrities can be influential, and it’s a good thing that people see science supported by celebrity.
But of course we should also be careful not to put celebrities on too high a pedestal. Yes, Bialik has beliefs unsupported by science. But so does everyone. I imagine if we dig into the histories of the other four women shown in the picture we’ll find all sorts of things that go against the foundations of science, just as you would if you examined anybody’s thoughts. I have met my fair share of scientists who believe in one thing or another without evidence, or despite it. Heck, you can find Nobel scientists who fall into that category; ones who have supported clear crackpottery.
I’ll note I’ve dealt with this before when I was at an event with a Miss Utah; though she and I would disagree strongly on a number of topics, she was also an outspoken promoter of STEM, which is why she was there. And I was glad she was there, doing what she did. Think of it this way: If you knew of someone who did a great job taking down psychics, but also thought global warming was a hoax, would you then stop praising them for their work against psychics? It’s not an either-or thing; I would hope you would continue to praise them where appropriate but also take them to task where needed, too.
While you might dismiss those ideas and think less of the person holding them, that doesn’t necessarily subtract from their contributions to science. In this case, Bialik has done a lot to raise awareness of science and women’s contributions to it. Celebrating her (and the other four actresses) for that is great, and that was the sole purpose of the picture, and it’s appropriate to praise her there.
That doesn’t mean I am forgiving of Bialik’s beliefs at all. And in fact her presence in the picture has brought attention to them, which I think is also a good thing. A lot of folks agree with her when it comes to health issues, and that’s a big problem in this country; I’ve been clear about that for years.
That’s what I meant about this not being black-and-white. We’re all shades of grey, and if you really only want to praise someone who is absolutely the perfect icon of science in every way, well, good luck finding them. You’ll be looking a long time.
As for me, I will continue to support science the best I can, and also support women in science. That’s the bigger picture here, and one we should all bear in mind.
[Note: The friend I mentioned above, Christina Ochoa, is part of a group of actresses (also friends of mine) who love science. They call themselves Scirens and you should follow them on Twitter. They're good people, and I’m pleased to help support their efforts.]
Tip o’ the calculator to Joel Parker for the link to the video.
I love photos of the Earth taken from space; our deserts, oceans, islands, volcanoes, farmland, forests … all of it.
But there’s something special about seeing something recognizable, even iconic, from space. Perhaps we’re used to seeing such things on maps, but a photo of it adds the dimension of reality.
I’m not sure. But no matter why, it’s hard to deny this is just straight-up cool:
I’ve spent a lot of time on this peninsula; family vacations when I was younger, visiting friends when I was older, watching the odd rocket launch or three. My folks lived there for many years, so seeing this from space reminds me of combing beaches for shark teeth when my daughter was little, getting sunburned like an idiot despite slathering on lotion, sweating maniacally in March.
At night, from space, the outline of Florida makes it so obvious (like Italy; perhaps peninsulae are easier to recognize). The lights of the city are both lovely to see and appalling to seriously consider; the light pollution is overwhelming, ironically drowning out everything in the night sky except for the few brightest objects … like the International Space Station passing overhead, from where this photo was taken.
Our technology has made it possible to go up and look down, but much harder to stay down and look up. If there is some sort of allegorical conclusion to be drawn here, well, I’ll leave it for you to consider.
OK, so the title is a little tongue-in-cheek, but it's sorta true: Mineralogists have finally found naturally-occurring samples of what may be the most common mineral on Earth: what’s called silicate perovskite, or (Mg,Fe)SiO3.
They’ve also officially given it a name now too: Bridgmanite. Percy Williams Bridgman won the Nobel in 1964 for studying high-pressure minerals… and that’s a clue to why this mineral was so hard to identify.
Bridgmanite can only exist under conditions of high temperatures (at least 2100°C) and pressure (240,000 times the sea level atmospheric pressure—a crushing 240 metric tons per square centimeter!). It’s thought to be abundant in the Earth’s lower mantle—a region 660 to 2900 km beneath Earth’s surface. The molten rock in the mantle is fluid, moving incredibly slowly inside our planet. Any bridgmanite in the mantle brought up toward the surface slowly breaks down under the cooler and lower pressure conditions, which is why it’s remained elusive, even though the mineral may make up as much as 90 percent of that part of the mantle (and therefore more than a third of the entire planet).
The scientific break came in the form of a meteorite, called Tenham. Long ago, two asteroids collided, and the impact created high temperatures and pressures. Bridgmanite formed, and the piece cooled too rapidly for the mineral to decompose. In 1879 the rock fell to Earth in Australia, where it was found and eventually determined to have different kinds of high-pressure minerals in it. Bridgmanite exists in it in very small grains, typically only about 1 micron wide (a human hair is typically 100 microns in width), but it’s there. It was announced earlier this year, but the scientists just published their paper about it in November.
This is quite a boon! It’s difficult to reproduce the conditions in the deep Earth, and even if you can it’s even harder to study what you get. In this case, it’s like we got a sample of the Earth’s lower mantle for free. It’s also a nifty crossover between different disciplines: Meteoritics, high-pressure physics, mineralogy, just to name some.
And also, it’s just amazing. We live on a ball of rock and metal 12,740 km across, with a staggering 1 trillion cubic kilometers of material in it, the vast vast majority of which we can never directly see. I wasn’t even aware that we didn’t actually know for sure what made up over a third of our own planet.
Science! Astronomy may be my passion and my love, but sometimes it’s good to remember that science also tells you, literally, what’s going on right underneath your feet.
Because why not, here’s a luscious time-lapse animation of the sky over La Palma, Tenerife, and El Hierro, three of the Canary Islands off the coast of Morocco:
I’ve been to La Palma, and the clouds really do roll in like that. I like how you can see them swell and disappear over the city (I think it’s Santa Cruz in the video) like waves on a beach.
Also, toward the end (at the 1:55 mark), there’s a star trails shot where the long exposure shows the stars as streaks due to Earth’s rotation. Stars on the celestial equator—the part of the sky directly above the Earth’s equator—make straight lines, but toward the right (north) and left (south) they curve more, as they circle the pole. But they curve in opposite directions!
That’s just the natural consequence of the wide-angle shot, being able to see the motions of stars across a big chunk of sky. Near the celestial poles, the stars make smaller circles, so we see the curvature of their trails changing with position. I have a more detailed explanation in an earlier post, if you’re curious (and you should be!).
Seeing this makes me want to get under the stars again... and now that it's winter, Orion, Taurus and all the wonderful chilly weather stars are back at a decent time of night. Time to warm up my camera...
Just yesterday I wrote about the good folks who create video at NASA’s Goddard Space Flight Center. And now I get to do it again: They just released their Dial-A-Moon page for 2015, which lets you display the hour-by-hour appearance of the moon for the entire year.
They also put out a video compiling all the images for the year into a single animation. You might expect it to look like the Moon is just sitting there, with the phase changing as the terminator (the day/night line) sweeps across its face. But that’s not what you get at all. Watch:
The Moon orbits the Earth in the same amount of time it takes to spin once. This means it always shows us the same face… except not really. The Moon’s rotation is constant, but the velocity it travels in its orbit around the Earth changes because that path is an ellipse. When it’s closer to Earth it moves faster, and slower when it’s farther away. This mismatch lets us peek a bit “around the side” of the Moon. The Moon’s spin axis is also tipped a bit with respect to its orbit, and that allows us to see over the northern and southern poles, too.
When added together, you get that mesmerizing nodding and weaving motion, which is called libration.
The video has some nifty extras too. At the top left it shows the Moon’s position in its orbit around the Earth, as well as the phases of both the Earth and Moon.
Behind the big Moon in the center is a line representing the Moon’s orbit seen edge-on. On the left is the Earth, and on the right it shows how far away the Moon is, in units of the Earth’s diameter (12,740 km or 7900 miles).
On the bottom left is a diagram of the Moon, with a blue and yellow dot; the blue is the sub-Earth point and the yellow is the sub-solar point. In other words, if you were standing on the Moon at the position of the blue dot the Earth would be exactly overhead, and if you were at the yellow dot the Sun would be directly overhead. Note that when the Moon is full to us on Earth, the yellow dot is smack dab in the center near the blue dot: The Sun is shining straight down on the half of the Moon we see. When the Moon is new (completely dark), the yellow dot is on the far side of the Moon; the Sun lights up the half we can’t see, and the half facing us is dark.
Finally, on the lower right are lots of fun numbers: Date/time, the phase (percentage of the Moon illuminated as seen from Earth), how big it appears, how far it is, and so on.
If you’re planning any detailed lunar observations, the GSFC page is pretty useful. I know I’ll use it to plan our future Science Getaways trips; we try to schedule them around new Moon so we can see the stars when I take my telescope out.
And even if you don’t need that kind of detail, this is just a way cool thing to have around. There’s also a video that shows just the Moon without any of the annotation, and a view as seen from the Earth’s southern hemisphere as well, with the Moon upside-down. Wacky southern hemisphereans.
And don’t forget this is a simulation, based on images taken by the Lunar Reconnaissance Orbiter. The real thing is eve better, so go outside and look! You may get inspired. A couple of friends of mine were.
So in my post about the Geminid meteor shower yesterday, I said that I didn't catch a single Geminid in my photos, and that's true. But going over them carefully, I happened to see something a bit weird, and I'm not sure what to make of it.
I took many shots of Orion, since it was perfectly placed over a tree, and any meteors going across it would make for a great photograph. I kept the exposures to 20-30 seconds, since the sky background was pretty bright, and I didn't want the stars to trail too much. While I didn't get any Geminids, I did happen to see this tiny streak:
You can see the three stars in Orion's belt at the top, and the fuzzy glow of the Orion Nebula, the nursery to a lot of young bright stars. And there, just below the third star in Orion's "dagger," there's that little blip. Is that a meteor?
I'm not sure. It's not a Geminid for sure; given Orion's position in the sky, a Geminid would leave a left-to-right streak in this photo. It's not in the previous or following photo, taken seconds earlier and later.
I'm not sure what to make of it. Most meteors would leave much longer streaks, but if the bit of cosmic debris happened to be heading almost straight toward me, it would leave a short streak due to perspective. If it's not a meteor, what could it be? Sometimes subatomic particles can leave similar streaks in a digital detector (these are typically called cosmic rays), but I've never seen one in my usual use of a regular camera. It may have been a bird lit by city lights, but the streak doesn't wiggle, and is so short that seems pretty unlikely. Same for an insect much closer to the camera.
It seems weird to think that a small bit of interplanetary debris sloughed off by some ancient collision between two asteroids millions of years ago and hundreds of millions of kilometers away may be the least unlikely explanation, but there you go.
Astronomy does sometimes provide an unusual perspective.
That picture shown above is, seriously, a full-color photo of the comet 67P/Churyumov-Gerasimenko.
It was taken by the Rosetta spacecraft on Aug. 6, 2014, when the probe was still 120 km (75 miles) from the comet (long before the Philae lander was deployed). The OSIRIS camera on board has red, green, and blue filters that allow the camera to mimic what the human eye sees. It’s not exact, but it’s close.
And what you see is… grey. Which means the comet really is just kinda overall grey.
That doesn’t surprise me. Comets aren’t really loaded with the sorts of colorful minerals that make Mars or Europa or even our own Earth so gloriously hued. They’re mostly water ice and rock, with other things thrown in for good measure.
But you might expect some variation when you look at the comet in detail. But it’s very smoothly grey; there’s very little change in the color composition across the comet. That means there’s probably physical homogeneity across its surface. If there are any interesting minerals or materials in the comet, they appear to be distributed pretty well.
That does surprise me; I was expecting to see patches of ice at least on the surface, and those reflect blue light better than red. But we see no blue patches at all. The water ice in the comet is mixed in with the other stuff.
That’s not the case with other comets; for example, Hartley 2 is also double-lobed, with a waist in between them, similar in shape to 67P. But observations using the EPOXI spacecraft show the waist is emitting water ice, while the lobes blow out more carbon dioxide. The waist is also smooth in appearance, while the lobes are rougher. It’s unclear why this might be.
But 67/P, for all its similarity in overall shape, is clearly a different beast than Hartley 2. That’s telling us something. Perhaps they were born in different parts of the solar system, and so are constructed differently (we know that to be the case for some by looking at isotope ratios in different comets). Maybe something happened as they aged—4.55 billion years is a long time, after all—that changed them. It could be that 67/P's outgassing and dust have coated its surface everywhere. Or maybe comets are just a diverse group, every one different from another. None of these circumstances would be surprising.
There’s another possibility, too: Simulations of the early solar system show that our Sun may have stolen the vast majority of its comets from other stars! If that’s the case, then that would go a long way toward explaining why comets are so different from each other. They were born in different solar systems!
It’s hard to express just how awe-inspiring that is. We’ve always assumed comets were like time capsules from the ancient solar system (if weathered and worn over the eons). But they actually may be samples of alien stars, transplants from elsewhere in the galaxy.
Thinking about this literally raises the hairs on the back of my neck.
So gaze upon that photo of 67/P once again, and think about what you may be seeing. I know I’ll never use the word “grey” to mean boring ever again.
Speaking of vaccines, my pal Maki Naro is a fantastic illustrator and pro-science guy, and he just put up a wonderful comic about why vaccines are important.
I love this. He hits on lots of critical topics, like how our immune system works, how vaccines prime that system to fight off diseases, why herd immunity is important, and why it's hard to keep up with evolving viruses.
Just as importantly, he hammers the anti-vaxxers who so richly deserve it, like Jenny McCarthy, Andrew Wakefield, and RFK Jr. Maki shows why their claims are not just wrong but in most cases hugely, egregiously wrong. And it's all done in a lovely, palatable comic form, making it easy and fun to read.
Maki draws more comics like this for Popular Science, too. I like his style, and I hope you do too.
Over the weekend, the Geminid meteor shower came to a peak. This annual event occurs when the Earth plows through debris left behind by the asteroid 3200 Phaethon as it orbits the Sun (it gets so close to the Sun that bits of the rock vaporize and blow off the asteroid). Each little bit of interplanetary detritus is moving at about 35 kilometers/sec (22 miles/sec), fast enough that as it rams through our air, it heats up enough to become incandescent, and we see a “shooting star.”
I was out Saturday night (Dec. 13), and over the course of two hours I saw so many I lost count; I’m pretty sure I spotted at least 80. I wasn’t able to get any Geminids on camera (grrrrr), but happily photographer Neil Zeller had far better results:
Spectacular! He drove up northeast of Calgary to get nice dark skies, and it was clearly worth the trip. The photo is actually a composite of several exposures; he was facing northwest and captured the Milky Way, several Geminids, and a lovely green aurora on the horizon (Zeller has an astonishing gallery of aurora photos on his website). On the far right you can just see an interesting pair of stars tightly spaced; that’s Mizar and Alcor, the stars in the bend in the Big Dipper’s handle.
As you can see, all the meteors seem to point in the same direction. That’s because they do! The meteors appear to come from a part of the sky near the head of Gemini (hence their name), and radiate away from that point in all directions. It’s a perspective effect, like driving through a tunnel and seeing the lights on the walls appear to come from the same spot ahead of you, and streak away to the sides.
As I stood under the chilly Colorado sky Saturday, this radiating effect was pretty strong; I saw meteors in any part of the sky I looked, and they always pointed back toward Gemini (except for one that was a random meteor unrelated to the shower; on any night you can usually see a few per hour). I saw every flavor of meteor, too: long streaks, short ones, faint ones, bright ones, and one that flared about as bright as Jupiter (magnitude -1 or 2 if you want details) that left a luminous vapor trail that lasted for just a second or two. That was amazing.
This was easily the best meteor shower I’ve ever watched myself. It’s usually too cold and cloudy this time of year to see it, but things worked out well; in fact, as I write this (the day after the shower) it’s snowing!
And I did get a lot of very pretty pictures from the night, including this one of Orion through the trees (and Sirius, the brightest star of the night sky, to the lower left). It was totally worth the cold fingers, toes, and nose.
Tip o' the lens cap to Daggerville on Twitter.
Hmmm, it’s been a while since I’ve posted on how anti-vaccination propaganda is making people sick and putting children needlessly at risk for terrible diseases.
[Opens up map, looks around, sees blinking red alarm light over Michigan.]
Ah, Michigan, that bifurcated mitten by the lake. I spent three years at U of M, and grew quite fond of it.
But then, I didn’t get measles or whooping cough while I was there.
You have a decent risk of that now, thanks to low vaccination rates. In Traverse City, a recent outbreak of pertussis forced the closure of a charter school with 1200 students (there were 10 confirmed cases and 167 probable cases) and infected children at 14 other schools.
Why did this disease hit schools so hard? The reason is almost certainly exactly what you’d think: Vaccination rates for children in schools are low, because parents have been opting them out.
Most states have mandatory vaccinations for children to attend public schools, but they also have opt-out waivers for parents who don’t want their children vaccinated for religious reasons… and for “personal reasons”.
This means anti-vaccination reasons. And you know how I feel about that. Virtually every claim made by anti-vaxxers is wrong, or a gross distortion of the truth. The actual truth about vaccines is that they are extremely effective and their risks are minimal.
I’m not a fan of religious waivers—especially when it comes to health care workers, for example—though I understand that’s a political hot potato (even though, in reality, very few religions forbid vaccinations).
But personal waivers? The more I think about it, the more I come down pretty clearly on it: If your child is able to get vaccinated, and you choose not to do so, then your child is not allowed in a public school.
It’s that simple. I’ve made this argument before:In some areas, public school authorities have mandated that students be vaccinated for various diseases, and that of course can run afoul of parents’ beliefs. I’ve wrestled with this problem for a while, and I eventually came to the conclusion that a parent does not have the right to have their child in a public school if that child is unvaccinated, and for the same reason health care workers should not be unvaccinated. It all comes down to a very simple reality: It puts other children at risk. If you want to rely on the public trust then you have an obligation to the public trust as well, and part of that obligation is not sending your child to a place with other children if they aren’t immunized against preventable, communicable diseases.
When you send your kid to a public school, this is no longer a personal decision. It’s a very public one, and you are putting thousands of people at risk for diseases that can cause grave harm, and even be fatal. And yes, I’m vaccinated, and so are my wife and daughter, but not everyone can get vaccines due to health reasons (people who are immunocompromised, for example). Some babies are simply too young to get vaccines yet, for example, and they are at very high risk for infectious diseases like pertussis and measles.
And that, I am very sad to say, matters very much.
I have said this before, and as long as we have outbreaks of diseases due to low vaccinations rates I will continue to say it: Don’t listen to the anti-vax rhetoric. They’re wrong. Instead, talk to a board-certified (i.e. non-quack) doctor and find out if you need to get your vaccinations (including boosters) and if you should vaccinate your family.
People shouldn’t be dying because of diseases we can easily prevent. But they are. Do your part.
Thanks to Luke Schmerberg for sending me the news about Michigan.
We live on a whirling ball of rock thousands of kilometers across. As it happens, most balls of rock that size in the Universe are whirling, so it’s not really weird. It just seems weird.
The reason it seems weird is that the rotation of the Earth is pretty slow when it comes to things we can perceive; it’s not like being on an amusement ride with a small radius and rapid spin. We’re pinned to the surface of a planet, and it’s huge.
We’ve evolved over a zillion years to think the Earth is fixed, and the sky spins around us. That’s why we say the Sun rises, and not “the Earth’s west-to-east angular motion has caused a reflexive apparent motion in the otherwise nearly fixed Sun such that it seems to move in a westward fashion above the eastern horizon”, which honestly, would be too pedantic even for an Internet commenter.
But it’s true. The stars move across the sky because we move under them, we just don’t see it that way.
But what if we could? I bet it would look like this video by neurologist and photographer Alex Rivest:
Wheee! That’s fun. He took some time-lapse animations of the sky, then set them up so the stars stay fixed, letting the ground move (he was inspired to try this by a video created by José Selgado). It’s an odd, and subtly disturbing effect. It was neat to see his Mt. Everest footage in there, too.
I also stumbled on an interesting illusion: If I kept my eyes on a feature in the sky (a star, or a dark patch in the Milky Way) it does look like the ground is rotating, but if I looked near the edge of the frame, or right where the ground and sky meet, it looks like the stars are moving, or a weird combination of both sky and ground moving.
Our brains are ridiculously easy to fool. But you knew that, right?
I don’t know why cool cloud patterns seen from space fascinate me so; maybe it’s just my inherent love of science, clouds, space, nature, and art.
Actually, after writing that sentence, maybe I do know why.
Also, sharing that love is fun, too. So for you, here is a really nice shot of a wave cloud pattern seen by Landsat8:
What you’re seeing are called “ship wave clouds”, because the overall pattern resembles the waves of water as a ship moves through the ocean. The cause of this is Île Amsterdam, an incredibly remote and tiny volcanic island located in the southern Indian Ocean. It’s only about 10 km across, and the peak reaches to about 850 meters above sea level. You can just see the edge of the island on the left hand side of the image, peeking through the hole in the clouds.
As a steady wind blows over the volcano, it rises up and cools. Moisture in the air condenses, forming clouds. But as the air cools it sinks, warms up, and the water evaporates again, so the clouds disappear. The warm air rises, and boom! Repeating pattern. At the same time, the wind gets pushed around the volcano as well, so the pattern gets wider downstream.
This photo is one of the best I’ve ever seen of the phenomenon… though when it happens over an island chain it’s pretty amazing as well. I see similar things sometimes as the wind blows over the Rocky Mountains, just a few kilometers to the west of my home. When wind, water, and geology interact, it’s a canvas on which nature paints nearly infinite varieties of beauty.
Note: This post is an updated version of the viewing guide I wrote last year.
If you’re looking for a way to see an amazing sight while simultaneously freezing your butt off, do I have the meteor shower for you: the Geminids!
This annual shower peaks on the evening of Dec. 13-14 (Saturday night/Sunday morning), when there should be very roughly 100 meteors per hour. Unfortunately, the third-quarter moon rises around midnight, which brightens the sky and makes fainter meteors harder to see. Still, it's worth going out and taking a look!
Watching a shower is pretty easy; all you have to do is go outside, look up, and be patient. Shooting stars are somewhat random, so you might not see any for a few minutes, then you’ll see three in a row. The longer you wait, the more you’ll see.
But there are some things you should know. If you have clear, open skies, and follow the instructions below you, should have a celestial event to remember!
Usually, meteors are best seen after local midnight (literally, halfway from sunset to sunrise) because that’s when the Earth is facing into the oncoming meteors (like seeing more rain hitting your front windshield when you’re driving in a storm). However, in this case, any time after about 10:00 p.m. should work. The meteors appear to radiate away from a point in the sky in the constellation of Gemini (see #2), which is well above the horizon by then. The later you wait the better, but remember the Moon will start to mess things up after it rises at midnight.
Once you're outside, it takes about 20 minutes for your eyes to get fully adapted to the dark—your pupils dilate, letting in more light, and your eye produces a light-sensitive protein called rhodopsin. Both of these take time to fully kick in. So don't be disappointed if you see very few or no meteors right away. White light will bleach the rhodopsin, by the way, so if you need some light, use a flashlight with red cellophane covering the front. That will preserve your night vision.
2) A Wide Open Sky
This is really important. Meteors appear in random spots on the sky and can go from horizon to horizon. The more sky you can see, the more meteors you'll see. Try to avoid nearby buildings, trees, and so on.
If you trace the path of the meteors backward, they will appear to radiate from one point in the sky located in the constellation Gemini (hence the shower name). This is the same effect as when you're driving a car through a tunnel and the lights on the walls and ceiling appear to come from the point ahead of you. A good view of Gemini will up the odds of seeing more meteors. If you can find Orion, Gemini is to its upper left (for folks in the northern hemisphere; in the southern hemisphere this shower isn't nearly as prolific because Gemini is much lower in the sky).
No matter what, a big wide view is your best bet.
3) Dark skies
Meteors are generally not terribly bright. A few can be blazing, but most are about as bright as your average star, so you want to be away from lights. Your backyard might be fine, but make sure street lights are blocked and your house lights are off.
4) A Lounge Chair
You need to be able to see a lot of the sky for minutes or hours, so you want to be comfortable. A chaise lounge or a folding beach recliner is a big plus. You can lie on the ground with a blanket if you want, but comfort is important if you're going to be out for a while. The ground tends to be cold at night and wet too. Which reminds me ...
Hello, it’s December, and that means it’ll be cold. You won't be moving much, either, so you won't be generating much heat. You won't see many meteors if your teeth are chattering (I imagine hypothermia won't help either). Stay warm!
6) Telescope, Binoculars
I recommend not using a telescope. Why not? Telescopes see only a small part of the sky, and meteors appear in random spots. I guarantee the best meteor of the night will happen while you are stooped over an eyepiece, and you'll miss it. However, Jupiter is well positioned for viewing, so this is as good a chance as any to do some observing, and I hate to tell people to not take advantage of a nice night! But be prepared to hear everyone else gasp and then mock you for missing the best meteor ever.
Binoculars are better. You can scan the sky, look for interesting things, and still be able to look around quickly if a bright meteor appears.
7) Star Chart
Hey, you're outside! Why not get familiar with the sky? You can find charts at local bookstores and online if you do a little searching. Orion, Gemini, Taurus, the Pleiades ... this is a fine time of year to be out looking for cosmic landmarks.
Oh boy, is this one important. It's after midnight, you're lying down, snuggled in a blanket, it's dark, and your eyes are focused on infinity. You start daydreaming a bit ... and the next thing you know, the Sun is rising and you're covered in frostbite.
Take a nap this afternoon if you want.
9) Friends, Family, Neighbors
Having other folks with you will help you stay awake, and honestly, the joy and beauty of a meteor shower is best shared. One of my favorite times ever with The Little Astronomer was watching the Leonids shower when she was little. She had a blast, and not just because she got to stay up until 3 a.m. with her dad ... but then again, that's a big part of it, too.
10) An Appreciation of What You Are Seeing
Read up on meteor showers, what they are, what we've learned from them. The Geminids are debris from an asteroid called 3200 Phaethon, which sometimes acts a bit like a comet (every other shower comes from debris sloughed off by comets). Asteroids orbit the Sun for billions of years, and you're seeing tiny parts of them—most no bigger than a grain of sand—as they slam into our atmosphere a hundred kilometers above you at speeds of up to 40 kilometers per second. How cool is that? The shower has an interesting history as well, and it's always fun to know more about an event, especially one in which you're participating.
This may be the best thing to bring, and the easiest. Meteor showers are simply wonderful. It's a cosmic show, and it's free, and it's very, very cool.
Facebook is to misinformation what a high school is to mono. Basically, it gets in there, and boom! Everyone shares it.
The culprit this time is a picture claiming to be an aurora taken from space. Here’s the photo:
I saw this linked from a Facebook page called ScienceDump, one of those accounts that posts pictures that are vaguely sciencey, and only sometimes gives links to further info or attribution for the images.
In this case, the only caption given was, “Ring of Fire. A picture taken by NASA of the Northern Lights from space.”
I knew right away that caption was completely wrong. For one thing, the Earth, stars, and aurorae simply don’t look real. Note the complete lack of clouds, for example. Second, the aurora aren’t that tall; those streamers are hundreds of miles in height, but in reality aurorae sheets are only a few miles in height.
I did a reverse image search using Google, and at first just found the usual reshares of this photo. I did find a few sites debunking the picture, but none knew where it was from. My biggest clue came from the sattrackcam blog, which dissects the image pretty well, but also mentions the shot was used in a video.
That gave me an idea. NASA’s Goddard Space Flight Center has an excellent video team, and I know a lot of their animations are online. I started poking around on their site, and it took a little while, but I finally found the exact original video this image is from!
The image comes in at the one-minute mark. The whole video is clearly computer generated. In fact, there’s a credit at the bottom of the GSFC page: “Visualizer/Animator: Walt Feimer (HTSI) (Lead)”; HTSI is for Honeywell Technology Solutions Inc. The video was created under contract to depict how the Earth’s magnetic field channels subatomic particles from the solar wind down into the atmosphere, where they make the air glow.
It only took me a few minutes to figure this all out. I did have the advantage of knowing about GSFC’s video page, but this ScienceDump page didn’t bother with fact checking or credit at all. Whoever runs it just made up a caption and ran with it. I’m no fan of these kinds of accounts; I see a lot of them on Facebook and Twitter, posting blatant garbage and claiming it’s real. ScienceDump appears to be marginally better than most, linking offsite to other sources. But this aurora photo shows it’s not 100 percent.
A good antidote for all this is to follow @FakeAstroPix and @PicPedant on Twitter (want a chuckle? Check out PicPedant’s background picture on their Twitter page; I could’ve saved myself some effort). @HoaxOfFame looks good, too. And, of course, there are hundreds of science communicators out there you can follow on social media to get the real scoop on real science.
I know that urge to retweet and share these kinds of photos can be strong, but I urge you not to subscribe to those kinds of accounts. Don’t get me wrong: It’s nice to get people excited with cool pictures and factoids, but from what I can see a lot (many? most?) of these sorts of accounts just post pictures while rarely giving credit or explaining them. And worse, a lot of them post total nonsense and even faked pictures, passing them off as real.
I’ve said this before, but it’s probably worth saying again, many times: The Universe is cool enough without making up crap about it.
We call Earth a water world, and that’s pretty fair: Our planet’s surface is 70 percent covered in it, it makes up a percentage of our air, and there’s even a substantial amount of it mixed in to the planet’s mantle, deep underground.
But where the heck did it come from?
This is no idle question. We have a lot of water here, and it must have come from somewhere. There are two obvious sources—it formed here along with the Earth, or it was brought to Earth from space. Which is the dominant source has been a topic of long and heated debate among astronomers.
The first big science results have just been announced by the European science team working with the Rosetta probe, and, in my opinion, they throw more gasoline on the fire. Measurements made by the probe show that comets like 67P/Churyumov–Gerasimenko—the one Rosetta is orbiting—couldn’t have been the source of our water.
But that hardly helps answer the underlying question! Why not? Ah, the details…
When the Earth formed 4.55 billion years ago (give or take), there was a lot of water in the disk of material swirling around the Sun. Close in to the Sun, where it was warm, that water was a gas, and farther out it formed ice. We see that latter part echoed down through time now in the form of icy moons around the outer planets.
You’d expect water collected on Earth along with everything else (metals, silicates, and so on). When the Earth cooled, a lot of that water bubbled up from the interior or was outgassed by volcanism.
But we have another big source, too: comets. These are dirty snowballs, rock and dust held together by water frozen as ice. They formed farther out in the solar system, where ice was more plentiful. Long ago, just a few hundred million years after Earth formed and started to cool, there was a tremendous flood of comets sent down into the inner solar system, disturbed by the gravitational dance of the outer planets as they slowly settled down into their orbits. This Late Heavy Bombardment, as it’s called, could have supplied all of Earth’s water.
How to tell? Well, it turns out that in this one case, hipsters are right: Locally sourced is measurably different than stuff trucked in.
Water is made up of one oxygen atom and two hydrogen atoms. Hydrogen atoms, it so happens, come in two flavors: The normal kind that has single proton in its nucleus, and a heavier kind called deuterium that has a proton and a neutron (there’s also tritium, with two neutrons, but that’s exceedingly rare). Deuterium is far more rare than the normal kind of hydrogen, but how rare depends on what you look at. The ratio of deuterium to hydrogen in Earth’s water can be different than, say, water in comets, or on Mars.
Note I said, “can be”. We know the ratio differs across the solar system. But suppose we find the same ratio in comets as we do on Earth. That would be powerful evidence that water here began out there. Astronomers have looked at a lot of comets trying to pin down the ratio, and what they’ve found is maddening: Some comets have a ratio very different from Earth’s, and only one (103P/Hartley 2) has a ratio similar to ours.
Now that’s interesting: 103/P is a Jupiter-family comet, meaning it used to orbit the Sun far out, but dropped into the inner solar system, got its orbit modified by Jupiter, and now has a much shorter path that keeps it in the inner solar system.
Rosetta’s comet, 67/P, is also a Jupiter-family comet. You’d expect them to have roughly similar deuterium/hydrogen ratios.
They don’t. 67/P, according to Rosetta, has three times the deuterium per hydrogen atom as Earth (and 103/P).
What does that mean? It’s not clear, which is why this is maddening. It could be simply that not all Jupiter-family comets have the same ratio; they may all have different origins (born scattered across the solar system, so with different D/H ratios), but now belong to the same family. Or it could mean that 67/P is an oddball, with a much higher ratio than most other comets like it. That would seem unlikely, though, since we’ve studied so few you wouldn’t expect an oddball to be found so easily.
Making things more complicated, some asteroids in the main belt between Mars and Jupiter have water on them, and it appears to have an Earth-like D/H ratio. But we think they have so little water that it would take a lot more of them impacting the early Earth to give us our water than it would comets. That’s possible, but we know lots of comets hit us back then, so it’s still weird that the D/H ratios don’t seem to work out. Still, it’s nice that there could be another potential source to study, and this new Rosetta result does lend credence to the idea that asteroids did the wet work.
So if you ask where Earth’s water come from, the answer is: We still don’t know. No doubt it wasn’t a single source anyway, but came from multiple kinds of objects, which muddies the water (so to speak, though kinda literally).
The good news is, we’ve only studied a dozen or so comets this way, which is a pretty small sample. As time goes on we’ll visit and observe more, and perhaps be able to nail this down better. Same with asteroids; there are a lot of them, and they’re worth poking at too.
And that’s the fun of this. Maybe no single observation will give us that “Eureka!” moment, which means we’ll just have to do more amazing, fantastic, and awe-inspiring missions to comets. What a shame.
So you know the Earth is warming up—after all, it’s overwhelmingly obvious and the vast majority of climate scientists agree about it. But some people just can’t seem to accept that; in the loudest cases they’re ideologically driven (and/or fossil fuel–funded), but it’s possible that a lot of folks just don’t have the facts.
When you talk to them at a cocktail party (or at family dinners, what with the holidays and all that), things can get ugly fast. Short of running away or having your head explode, what can you do?
Here’s an idea: Show them this video from It’s OK to Be Smart, created by scientist and science communicator Joe Hanson.
Not bad! He covers a lot of the basic knowledge you need to counter most of the silly global warming denier claims. If you need more, I suggest Skeptical Science’s amazing list of climate myth debunkings, and Hank Green’s video debunking of ten common claims.
And if they bring up the so-called pause in warming, well, there’s been a lot of noise about it, but when you look at the data carefully, the pause disappears. And when people talk about this faux pause they only look at atmospheric temperatures, and even then a limited set of them. When you look at the heat budget of the whole planet, including the oceans, things look a whole lot less pause-y.
Studies have shown that presenting the facts by themselves doesn't usually work to change a person's mind, especially if those beliefs are ideologically based. Worse, in some cases it an make them dig in. That's one reason I generally don't engage with deniers and such on social media (also, they typically aren't interested in a real discussion anyway). But I think at the very least the facts need to be out there, and hopefully the information here will help.
A couple of months ago I posted an amazing time-lapse video called Stormscapes, showing storms and mesocylcones created by photographer Nicolaus Wegner. It’s really worth watching; seeing those swirling, dark clouds forming vortices over the Midwest is terrifying and mesmerizing.
Wegner contacted me recently; after a year of storm chasing he put together another video, Stormscapes2 and it’s way, way better than the first one. In fact, I’d say it’s seriously one of the most incredible weather videos I have ever seen.
Make this hi-def, full screen, and crank the volume up, because holy yikes.
From the opening sequence to the last frame, that’s magnificent. I was also really impressed by how Wegner let the music inspire the editing, and it really adds to the look an feel of the video.
The creepy oncoming storm sets the mood immediately, but then the double rainbow and crepuscular rays (shadows of clouds leaving long, dark shadows in the sky) converging on the horizon provide a brief interlude. Very brief.
Mesocyclones! Lightning! Exploding cumulonimbus clouds! Devil’s Tower! And then, at the end, one of my favorite kinds of clouds: bulbs of mammatus clouds hanging down. Those are really peculiar, and it’s not at all clear why they form. Their shape gives rise to their name, because they look like mammary glands. Seriously.
I’ve seen mammatus clouds just once, and it was unearthly. They’re harbingers of severe weather, and Wegner mentioned he got that sequence the day a series of tornadoes hit the town of Wessington Springs, South Dakota. The town was devastated, but due to the work of the National Weather Service, not a single person was killed. They predicted the conditions were ripe for tornadoes, issued a warning, and people were able to get to safety in time.
That’s amazing, but that’s science. We’ve learned so much about the weather that we can predict with pretty good accuracy where and when tornadoes can form, and get people to safety.
As I watch Stormscapes2, I’m in awe of the beauty of weather, but I’m also uplifted. We understand a lot of these phenomena very well, and the things we don’t understand, we learn. And when we learn, we make things better. We save people’s lives.
Science saves lives. That’s a pretty good thing to learn, too.