Bad Astronomy
The entire universe in blog form

Aug. 19 2015 7:00 AM

A Spritely Thunderstorm From Space

You’d think that by now, deep into the 21st century, we’d have a pretty good handle on how something as common as lightning works.

But in fact there are still lots of mysteries to these gigantic bolts of electrical current, and a lot of their behavior is either unknown to or misunderstood by the public.

For example, have you ever heard of sprites? These are extremely fast and faint discharges that occur above thunderstorms. Way above, actually, from 50–90 kilometers up in the atmosphere. Most thunderstorm-producing clouds only reach a dozen or so kilometers in height, but clearly their reach extends much higher.

Sprites are beautiful and fleeting, and extremely difficult to photograph. Well, until recently, when more sensitive digital cameras became commonplace. One thing that makes it tough is that the sprites occur so high up you only really spot them above storms on the horizon; if you’re closer, the cloud itself blocks them (the fantastic photographer Randy Halverson caught a sprite in a storm photo that I wrote about a while back).

… Unless you have a better vantage point, like, say, above the clouds. Way above, as in space. Then you can get fantastic shots like this:

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Aug. 18 2015 12:30 PM

OK, Fine: One More Gorgeous Perseids Photo

I know, I put up some photos of the Perseid meteor shower a couple of days ago, and again Monday. But c’mon. Look at this!

Aug. 18 2015 7:00 AM

One More Day to Reboot the Suit!

There is now one day left in the National Air and Space Museum’s “Reboot the Suit” Kickstarter campaign.

We reached the goal to conserve Neil Armstrong’s historic Apollo 11 EVA lunar spacesuit—the suit that he wore when he set foot on the Moon—in just a few days. We’re now achingly close to our stretch goal to be able to do the same with Alan Shepherd’s Mercury flight suit, which he wore when he became the first American in space in 1961.

I’m very proud to have been a small part of this project, and you can participate too. There are lots of rewards left! Pledge to support this goal, and let’s make sure future generations can see these important artifacts from the dawn of the Space Age. 

And please help spread the word; use the hashtag #RebootTheSuit on social media. Sincerely: thank you.

UPDATE, Aug. 18, 2015 at 16:00 UTC: WE DID IT!


Wait, no: YOU did it. Thank you so much to everyone who contributed, who spread the word, who helped out in any way they could. This means a lot to the people who are working on this project, and to me personally. I couldn't be more proud of what we — of what you — have done here.

Aug. 17 2015 11:30 AM

Amazing Astrophotography: Perseids, Fireball, Aurorae, and Weird Clouds

OK, I can’t resist: Above is another beautiful Perseid meteor photo, taken by Göran Strand in Sweden on Thursday. I love the colors in this one! In the original shot, you can see the stars of the Big Dipper above it, too.

But there’s more. See that green band above the horizon on the left? That’s the aurora! And not only that, but the weird, twisted, glowing clouds you can see near it are noctilucent clouds, a rare sight. These are very high altitude clouds made of very tiny ice crystals. They reflect sunlight, but are so faint they can only be seen when the Sun is below the horizon. Being at high latitudes (like Sweden!) helps too.

Pretty amazing. But there’s still one more thing. Strand was taking some footage of the area around his campsite when he spotted a very bright fireball, called a bolide. Here’s the video … but apparently I need to warn you; if you speak Swedish, there are some dirty words in this.

I don’t blame him. If I saw a bolide that bright, I’d swear in Swedish too!

Incidentally, he told me that the fireball was widely reported and appeared in the Norwegian Meteor Network reports, too. There’s stunning video of it, too!

Aug. 17 2015 7:00 AM

Global Warming Is Here and Now: July 2015 Was the Hottest Month on Record

Both NASA and the Japan Meteorological Agency are reporting that July 2015 was the hottest July on record—and those records go back to before 1900.

The Japanese chart makes this most clear:

july hottest ever
Japanese Meteorological Agency data show that this last July was the hottest on record. The plot shows deviations from the average temperature over the years 1981–2010.

Graph by JMA

That last dot on the right is last month, July 2015. There are several things to note right away:

  • This July is indeed the hottest on record since 1891,
  • The hottest Julys have all been the past few years,
  • The trend is upward, at 0.67°C per century,
  • 1998 was an outlier, the second hottest July on record.

Why is that last one important? Because 1998 had an extremely strong El Niño, and years with El Niños tend to be hotter. Guess what? There is a strengthening El Niño going on right now, and from all indicators it will be another extremely big one.

It’s becoming clear that 2015 will be the hottest year on record (2014 holds the record for now), and if the El Niño increases as expected, 2016 may be more of the same. As usual, Tamino has an excellent analysis of the July record.

Incidentally, the JMA site lets you change the month you can plot. When you do, you see that June 2015 was the hottest June on record. May 2015 was the hottest May. April 2015 was the third hottest April. And so on.

Another thing this makes clear: The idea that the Earth hasn’t warmed in the past decade or two is utter garbage. That’s been shown over and again, yet so many deniers still cling to it.

Guess where the Republican presidential candidates stand on this issue?

head in the sand
That sand is getting pretty damn hot.

Photo by Shutterstock/alphaspirit

Donald Trump, still embarrassingly the front-runner, thinks it’s a hoax.

Jeb Bush, arguably the Republican front-runner once whatever inevitably happens to Trump happens to Trump, at least makes noises that global warming is real but says the science is “not complete,” which is just more doubt-sowing; it’s denier-speak for an excuse not to do anything about it.

Scott Walker hasn’t been clear on his feelings per se, but his actions make his denial stance pretty clear. Ben Carson denies global warming is even happening. He joins Ted Cruz who still flat-out denies the Earth is warming at all, and Marco Rubio, who still denies humans are to blame. Mike Huckabee just spews long-debunked nonsense.

Carly Fiorina uses distraction and scare tactics as well to avoid taking any action on climate change, saying no country can do it alone. But she specifically talks about China, and China has in fact pledged to reduce emission (as have the EU and Mexico). The US looks foolish in the world market when it ignores as great an economic threat as global warming.

Etc., etc., ad nauseum.

This party-platform denial prompted the Hillary Clinton campaign to put out a video on it, which, though very snarky, lays it out pretty clearly:

Clinton seems serious about climate change, but I have mixed feelings so far. Bernie Sanders is much stronger on climate than any other candidate in either party.

Of course, the Republicans didn’t even bother discussing climate in their candidate debate. And in the meantime:

When will the GOP start taking this national and global threat seriously? They’re fiddling while the world burns.

Aug. 16 2015 7:30 AM

Parsing the Perseids

Last week was the peak of the Perseids meteor shower, one of the best and most reliable sky shows of the year. I received approximately eleventy billion tweets about it, and it seems that most folks saw several dozen meteors per hour.

I have old friends visiting, and we camped out on the driveway for an hour and saw a couple of dozen ourselves. Many were very bright, leaving visible glowing trains (what astronomers call the long streak in the sky left after the meteoroid itself burns up; it’s made of ionized stuff blown off of the rock as it rams through our air).

One of my favorite astrophotographers, Rogelio Bernal Andreo, took the above photo of the shower on Wednesday from Hawaii. It’s actually a composite of many photos he took over the course of 150 minutes; he chose the shots that had meteors in them, aligned them using the stars as references, added them together, and then used the landscape from a single photo to replace the bottom part of the picture (which would otherwise be blurred when the pictures are shifted to match the stars).

Several things jump out at me. You can see how almost all the meteors point to a single spot in the sky; that’s the radiant, the spot from which the meteors appear to radiate away. It’s a perspective effect. Any meteor in the image that does not have such a trail must be a random, sporadic one. You can usually see five or so sporadic meteors per hour on any given night.

Also, the meteor in the bottom middle, just to the left of the summit Mauna Kea, has a reddish horizontal streak next to it: That’s a persistent train, a train that can last for several minutes, whipped by upper level winds.

Also, all the way in the upper right? That fuzzy thing is the Andromeda galaxy. Directly below it is the constellation of Perseus, from which the shower gets its name.

Andreo has started a gallery of his work called Starscape Gallery, and it’s worth your time to visit.

In a related note, here's another photo that took me by surprise: It shows what looks to be a pair of meteors burning up in Earth’s atmosphere, taken from the International Space Station!

meteor from space?
Is this a photo of two meteors from space?

Photo by NASA

That photo was taken on Aug. 9, when the ISS was over the Indian Ocean. It’s hard to see the meteors; they’re in the middle right, just under the Earth’s limb. Here’s a close-up:

A closer view.

Photo by NASA

Given the timing, I thought they might be Perseids. But being suspicious, I opened Sky Safari and used it to identify the Milky Way features in the photo. I quickly figured out that the bright star on the left in the wide-angle shot is Alpha Centauri, and the one in the bottom middle is Antares.

The meteors appear to be coming from a spot not far from Antares, which is in Scorpius, a long way from Perseus in the sky. I think it’s a complete coincidence, and given their direction of travel I have to conclude they’re random meteors, not Perseids.

… assuming they’re meteors at all. They’re faint, and the exposure time of the photo was only four seconds. That would be quite a coincidence to capture any meteor at all in that short an exposure (and the one on the left points suspiciously close to Antares, making me wonder if it’s a reflection of some kind). It may be impossible to know.

But it’s still a cool picture. And a few years ago astronaut Ron Garan did photograph a Perseid from space!

The next really good meteor shower is the Leonids in November, and then the Geminids in December. I may try to photograph one or both, even though my last attempt didn’t go so well.

I may never do as well as Malin or Andreo, but it’s fun to try.

Tip o’ the Whipple Shield to Peter Caltner for the ISS photo. 

Aug. 15 2015 7:30 AM

Crash Course Astronomy: Brown Dwarfs

Last week’s Crash Course Astronomy was particularly fun for me, because I love the topic of exoplanets. It’s one of my favorite new fields of astronomy.

But not my only favorite. Another is brown dwarfs, objects between the masses of planets and stars. I’ve been fascinated by them since long before the first one was discovered, and I was in the right place at the right time (NASA’s Goddard Space Flight Center in 1997) to be able to help analyze Hubble spectra taken of one of the first ones ever seen.

Since that time we’ve learned a lot about them, and they are totally cool. And literally cool! Some have been found that are actually room temperature.

That’s why putting together this week’s CCA was also a lot of fun. See for yourself!

Two things I want to mention. One is a typo in a graphic of nearby stars. It should be Barnard's Star, not Baynard's Star. Little typos work their way in, and it's maddening when they get past me. Sorry about that.

The second thing is that sometimes I write something and do it on camera knowing what I’m trying to convey, but then later realize it can be interpreted differently. At about the 2:30 mark I mention that astronomer Jill Tarter was the person who gave brown dwarfs their name, and also mention she is a SETI scientist, looking for signals from aliens. The way I say that (“… and oh boy, we’ll get to that later!”) makes it sound like I’m disdainful of the search.

But I’m not at all! I actually meant that to be like, “Just you wait, there’s some cool stuff to come on this topic!” but the phrasing and inflection I used may not convey that the way I intended. Rest assured, I’ll be going over life in the Universe and the search thereof in a later episode, and I’m in favor of both.

Unless they’re Goa’uld. Those guys are jerks. 

Aug. 14 2015 7:30 AM

A Comet’s Eruptive Day in the Sun

Thursday at 02:03 UTC, the comet 67P/Churyumov-Gerasimenko reached perihelion: Its closest approach to the Sun. At that time, it was about 186 million kilometers from our star (for comparison, the Earth is about 147 million kilometers from the Sun at perihelion).

This happens once every time it orbits the Sun on its 6½-year path, of course, but this time is special: It has a visitor. The European Space Agency’s Rosetta probe has been tagging along with 67P for just over a year now. The spacecraft entered orbit around the comet on Aug. 6, 2014, the first time in human history a machine made by us evolved apes ever achieved such a feat.

The timing was critical, getting to the comet a year before perihelion. As the comet nears the Sun, the light warms the comet’s surface. Comets are rock, gravel, and dust mixed in with lots of different kinds of ice (water, carbon dioxide, carbon monoxide, ammonia, and more), so as the ice turns into a gas from sunlight, the comet sloughs off material. This forms the tails, for one thing, but also allows the spacecraft to observe the debris and learn about 67P’s composition and structure.

orbit of comet
The orbit of 67P, showing its position at perihelion.

Drawing by NASA/JPL

Rosetta arrived in plenty of time to catch activity rising. From Rosetta we’ve seen the venting in the surface, forming pits that grow over time. The comet is surrounded by a soft aura of reflected sunlight from the gas and dust, but that’s also punctuated by more focused thin jets of material coming from vents.

But on Wednesday at 17:35 UTC, a richer pocket of gas was reached by the warmth of the Sun. It erupted, forming the more intense and spectacular jet you can see in the image at the top of this post. There’s also a fan of light next to it, which is interesting. If I had to guess—and why not—I imagine that there was a warming pocket of ice under the surface. It reached a critical point and erupted, blowing out a small amount of material as it burst through the surface that expanded to form that fan, while a smaller hole focused the outflowing material into that lovely streamer.

Here’s an animation created from several images taken before and after the eruption.


In one sense it’s no coincidence that this happened at perihelion; as the comet warms, we see more activity. Getting that bright jet right at perihelion is something of a coincidence: It’s not like suddenly the comet abruptly gets warmer at that moment! In fact, it takes time for the warmth to seep down into the subsurface regions, so I expect we’ll see more activity after perihelion than before. But who knows?

And of course that’s the point. We don’t know, and that’s why we sent our robotic proxy to the comet in the first place. Even if we’ve observed the perihelion behavior of hundreds of comets from Earth, it’s still worth examining them up close. As comet hunter David Levy says, comets are like cats: They both have tails, and they do precisely what they want. They’re individuals, and only by studying as many as we can, in as much detail as we can, will we learn about them as a whole.

In June, the ESA confirmed that the Rosetta mission will be extended at least through September 2016, so the plucky craft will be able to continue to observe the comet for over another year as it draws away from the Sun. What will it see?

I don’t know. Let’s find out.

Aug. 13 2015 4:00 PM

“Here Is the Beautiful Place: Who Could Mistake It? Here Is Odysseus’ Hall!”

The airless moons of our solar system are testaments to impacts, their surfaces peppered with craters large and small.

And I do mean large. Saturn’s moon Tethys is an interesting place all on its own—an icy world 1,000 kilometers across—but its captivating mien is punctuated by an ungodly vast impact basin named Odysseus.

Did I say “ungodly”? It’s actually quite the opposite, or at least “godslike.” I explain what I mean in my biweekly article for “Space Odyssey.”

The article is subscription only, but for five bucks a month you get a lot of really solid content—not just me, but also from folks like Emily Lakdawalla and Lucie Green. I could compare that price to a cup of coffee (and its ephemeral effects), or downloading an app you’ll never use, or getting a forgettable movie off pay-per-view, but you know what things cost versus their impact on you. Five dollars ain’t much, and it delivers space right to your browser.

Aug. 13 2015 7:30 AM

Life in the Asteroid Belt Is Rough

Being a large object in the solar system means getting brutalized over the years, pummeled by millions of impacts. Some objects wear it well; Earth, for example, has an active surface built up by volcanoes and eroded by continental subduction, rain, and wind. After a few million years impact craters usually get worn away.

Other objects are active in other ways; undersurface oceans like on Enceladus and Europa tend to erase scars as well.

But airless, static bodies tend to proudly display their scars. And when you live out in the asteroid belt between Jupiter and Mars, you get a lot of them.

A lot.

That picture above is not of the Moon; it’s Ceres, the largest asteroid. At 950 kilometers across, it’s the largest target in the entire belt, and not surprisingly covered in craters. This image was taken by the Dawn spacecraft on June 24, 2015, from a height of 4,400 kilometers above the surface. It shows the part of the asteroid just on the edge of sunlight, the day-night line astronomers call the terminator. The craters on the edge of this region see the Sun low in the sky, so shadows are long, and elevated features (relief) are more easily seen. My favorite part is the one crater rim near the top right just high enough to poke into sunlight; everything else around it is in the shadow of night.

JPL just put out a video tour of Ceres using imagery from Dawn, and it's pretty cool. Watch:

You can also have some fun poking around at an interactive rotating map of Ceres put together by Google engineer Ian Webster. 

There’s a lot about Ceres we don’t know, but Dawn’s journey is our journey to understanding. What are the bright white spots seen, some in craters and some not? Are the reports of hazy features—suggesting outgassing—real, and confirmable?

We may know soon. Dawn has already lowered itself into a tighter orbit, moving a week after the image above was taken to a height of 2,300 kilometers. In mid-December, it will lower itself again down to an altitude of just 375 km. The resolution in the images will increase by a factor of more than 10 over the picture above.

A lot of scientists are hoping that will be enough to get the detail they need to solve some of the nagging questions this gigantic ball of ice and rock has been posing. And they are legion.

If you want to keep up with the mission’s status, check out the Dawn Mission Status Updates, and read the well-written and quite enjoyable Dawn blog. And you can always peruse the phenomenal images taken by Dawn as well. This is a great mission, and it’s doing great work.