Bad Astronomy
The entire universe in blog form

July 15 2016 9:30 AM

A Beauty That Hides a Beast

I’ve seen (and posted) so many pictures of spiral galaxies that it takes a lot to really get me to say, “Wow”.


This image stopped me in my tracks. It’s NGC 6814, a large spiral galaxy about 75 million light years from Earth. It’s a hair smaller than our Milky Way, about 90,000 or so light years in diameter, and it’s a real beauty.

July 14 2016 8:30 AM

Pluto + 1: A Year After New Horizons Made It a World

One year ago today, on July 14, 2015, the New Horizons spacecraft shot past Pluto and its system of weird moons, making space history (and the history of the mission itself is great reading). It was the first time a probe had been sent to an ice world specifically to study it in detail, and —depending on your personal viewpoint— Pluto was the first dwarf planet ever seen up close, or the last planet seen up close, or the first Kuiper Belt object seen up close.

Whatever. Pluto is what it is, and what it is is amazing, and beautiful, and most of all surprising.

Before New Horizons, we did know some things about Pluto. It has one large moon, named Charon, and four smaller moons. Pluto is very shiny and reflective, probably due to nitrogen snow and ice, while Charon is much darker. Crude maps made using Hubble observations showed that Pluto had darker and brighter regions, but Pluto is just too small and far away even for the world’s biggest telescopes to reveal surface features. So while we knew quite a bit about it, what we didn’t have was details.

That changed 366 days ago.


July 13 2016 11:58 AM

What Do You Do With a Problem Like Space Debris?

Space junk is becoming a real problem.

It’s a serious issue. There’s a common misconception that things in space are just kindof floating out there, moving slowly—and given videos of spacewalks and what we see in movies, that’s understandable.

But it’s wrong. There are thousands of satellites orbiting the Earth, moving at incredibly high speeds. Note the plural, “speeds”; not everything is traveling at the same speed or in the same direction. Two objects moving at 25,000 kph in different orbits can have a relative speed of several kilometers per second. At that velocity, a fleck of paint can have a catastrophic impact.

If two entire satellites collide, the problem is hugely worse; they create a shower of debris that expands and can hit more satellites, creating a cascade of debris. This was the basis of the movie “Gravity”, you may recall. That flick grossly exaggerated the problem for dramatic effect, but the overall idea was based on reality. In fact, in 2009 just such a situation occurred when a defunct Russian communication satellite slammed into Motorola Iridium satellite; the energy of the impact utterly destroyed the two and created two clouds of debris moving in different directions.

Space debris is a very real threat. What can be done about it? NASA and the Department of Defense have been cooperating on this for a long time, but the European Space Agency is looking into taking the next step: a satellite called e.Deorbit. It’s in the proposal stage, awaiting ESA approval to actually get started. But if approved, the hope is that it will be tag, snag, and bag large pieces of orbital debris, then perform a de-orbit burn to drop them both into Earth’s atmosphere where they will burn up.

It’s ambitious, I’ll say that, but the basic idea makes sense. It will use advanced imaging techniques to identify debris, approach it carefully, securely capture the debris (either by deploying a net or harpoon that will hook it, or a grapple that will grab it), then drop down to a fiery disposal during re-entry.

ESA put together a nice video explaining the concept:

I think this is a good step in reducing the problem. Bear in mind it’s one step; the problem of small (centimeter-sized) debris is still a huge one. There are quite a few ideas floating around (so to speak) on how to mitigate that, including using lasers to heat up the debris and change their orbit, dropping them down into the atmosphere to burn up, and a Japanese idea to use a space tether to create an electromagnetic field that alters the orbits of debris. It would also help to create satellites that shed less debris in the first place, and ESA is looking into that as well.

I’m all for that. If we go about business as usual, the space around Earth will get clogged with material, making routine access to space more dangerous. Something must be done, and it’s nice to see government agencies taking it seriously.

July 13 2016 9:00 AM

Juno’s First Light

This is pretty neat: The image above is the first one taken of Jupiter and its moons by the Juno spacecraft after achieving orbit last week*. This was taken on July 10, 2016, when the Juno was a little over four million kilometers from the giant planet.

In the shot you can see Jupiter in a way we can’t from Earth: half full. Jupiter is five times farther away from the Sun than Earth is, so when we look at it from our planet we’re always seeing it more or less full. Even when we’re off to one side in our own orbit, seeing Jupiter from an angle, that angle is so small that Jupiter always looks essentially full to us.

But once you get far from the Sun, the geometry changes. Juno approached Jupiter “from the side”, catching up to it in its orbit around the Sun. It then entered into a polar orbit around the planet, on a path that will take it over the poles of Jupiter. The first two orbits are very long and elliptical, and then it’ll fire its engine again (in October) to drop it down closer.

After it burned its engine for an astonishing 35 minutes Juno was on almost exactly the orbit planned. It dipped low over Jupiter, then started moving away. The image above was snapped on the outbound leg of that first orbit, less than a week into the 53.5-day journey around the planet.

Seeing Jupiter half full is pretty amazing to a seasoned astronomer like me. I’ve observed the planet hundreds of times through binoculars and telescopes, and this view of it is nothing less than jaw-dropping.

You can see some details in the clouds too, like two of the main dark belts (the reddish-brown bands) and lighter colored zones. The Great Red Spot shows itself too, that ridiculously huge storm that’s been around for centuries, and could easily swallow a few Earth’s without a hiccup.

Three of Jupiter’s four large moons are in the shot as well (Callisto, which orbits pretty far out, isn’t seen). Juno’s mission is focused on the planet, not the moons, so we won’t see any close-ups of them, though we’ll get more scenes like this in the future.

But just you wait. Juno’s orbit will take it as far as 2.7 million km from Jupiter at apojove (the point in its orbit farthest from the planet), then it will dive to a stunning 4,000 km above the cloud tops, screaming past the planet at nearly 60 kilometers per second, roughly 200,000 kilometers per hour! At that speed, it could get from the Earth to the Moon in two hours.

The point being, when Juno is close to Jupiter, it’s close. The images we’ll get from it will be staggering. They won’t come for a while yet, so be patient. I know they’ll be worth the wait.

* The very first image taken by a new telescope or detector is called “first light”, which I think is quite poetic and lovely. While technically this isn’t the first taken by Juno (we got a nice animation taken while on approach), it’s the first taken from orbit, so that counts.

Correction, July 13, 2016: I originally wrote "perijove" here (which is the closet point in its orbit to Jupiter) rather than "apojove". My apologies for any confusion.

July 12 2016 11:45 AM

Moon Photobombs Earth

NASA’s Deep Space Climate Observatory, or DSCOVR, is a satellite that orbits the Sun about 1.5 million km from the Earth. That’s a (meta)stable orbit that keeps it between the Sun and Earth, so that when it looks at our planet, it sees its fully illuminated face.

A couple of times per year the dances of the Earth, Moon, and DSCOVR line up so that it sees the Moon pass directly in front of the Earth. And when it does, it’s actually pretty magical:


Yes, this is a real animation, and not a simulation. It’s composed of images taken by DSCOVR on July 5 (a similar transit was seen in 2015). There’s a lot to see here! You may have noticed the Moon looks much darker than Earth. That’s real. The Moon on average reflects about 15 or so percent of the sunlight that hits it; the Earth is much shinier, reflecting closer to 40 percent.

The Moon looks funny, doesn’t it? Where are all the usual features you see in photos? They’re on the other side. The Moon spins once every orbit, so it always keeps the same face toward Earth. DSCOVR orbits the Sun farther away than the Moon orbits the Earth, so when the Moon passes between the satellite and Earth it sees what we would call the Moon’s far side. And because the Sun is behind DSCOVR, the Moon and Earth are both full. Or very nearly; it’s slightly off line, so you can see a bit of the unilluminated part of the Moon and Earth, both on the right. This means that if you were on Earth looking at the Moon, it would have been up during the day, and very close to its new phase.

DSCOVR orbit
Diagram of DSCOVR's orbit relative to Earth.


Also, just above the Moon’s path, to the right of center on the Earth, you can see the ominous swirling spiral of Typhoon Nepartak. This powerful storm swept over Taiwan and China, killing many people and doing extensive damage. Weather events like this are terrifying and devastating, but from so far away they’re disturbingly beautiful; it’s one of the most persistent and dark ironies of space exploration.

A large part of DSCOVR’s mission is to raise public awareness of our planet, and how important observing it from space is. Sure, it’s pretty cool when the Moon photobombs Earth, but there’s much more going on with these images. I suggest you explore them for yourself, and take a look at our planet … and see that it really is a planet, one of countless many, but for us the most important. For at least a little while longer, it’s the only one we live on.

July 12 2016 9:30 AM

“Clean” Coal? Yeah, Not So Much.

If you thought the upcoming GOP national convention was going to be anything other than a look into a parallel dimension, then here’s a taste of what to expect. On Monday, the Republican National Committee had a hearing to work out the wording for the GOP platform, their list of beliefs and goals supported by the party and its members.

During these hearings, one of the topics was the use of coal. David Barton, a delegate from Texas, had an edit he wanted to make to a sentence in the platform. Watch:

Here’s what he said:

I would insert the adjective “clean” along with coal particularly because [of] the technology we have now. So, “the Democrat party does not understand that coal is an abundant clean affordable reliable domestic energy resource.”

In a sense, Barton is right: The Democratic Party* doesn’t understand that, because it’s utter baloney. “Clean coal” is a myth, a marketing term. Coal isn’t clean. Not even close.

If you want to be honest, the term should be “cleaner coal,” or more accurately “somewhat less dirty coal.” Coal is one of the major sources of energy production in the U.S. (providing 33 percent of the total, comparable to natural gas). It gets burned, which turns water into steam, which drives turbines, which then generate electricity.

Coal has a lot of other things in it besides carbon, including mercury, sulfur, and more. These pollutants get into the air and cause a lot of problems, including thousands of premature deaths every year. Scrubbing these toxins out of the coal is costly and very difficult, though new power plants do a better job at this than old ones.

But the elephant in the room is that carbon. Burn it and it combines with oxygen to make carbon dioxide, and this of course is a greenhouse gas. Humans put about 40 billion tons of CO2 into the air annually, far more than any natural source on the planet (including volcanoes). Because this is heating the Earth up and changing the climate, it’s important to figure out a way to capture the carbon and somehow store it to prevent it from getting into the air. This is called “carbon capture and sequestration,” or CCS.

The problem? The technology to do this doesn’t exist. Not in any real sense of the word, that is. There have been some pilot projects done, but they’ve managed only to scratch the surface in the vast amount of CO2 released.

Now to be fair, I won’t say CCS is impossible. Perhaps, in a couple of decades, a few tens of billions of dollars invested, and a few technological breakthroughs, it may become a reality.

But right now? No way.

All of this makes it pretty clear that what Barton was peddling in his interjection of the platform committee hearings was pure nonsense. Calling coal “clean” is just this side of a lie, and at best is horribly misleading. Adding that word to the platform is just another fairy tale substituted for science by the GOP.

head in the sand
This is self-explanatory.


I’ll note that Barton himself is a fervent climate change denier; he gave testimony at a U.S. Senate hearing in 2007 that is loaded with scientific errors. Even then we knew that much of what he stated in that testimony is flatly wrong. He misstates the role of aerosols in global warming (confusing it with their role in hurting the ozone layer), talks about global cooling, and more. He has a colorful history with reality, too.

I’ll also note that the leader of the platform committee, Sen. John Barrasso (R-Wyoming), is also a climate change denier. Because of course.

Once the Republicans finish hammering out their platform and put it online I’ll take a look at it, but you don’t need to be psychic to know what it will say about a lot of the issues. The party’s guiding principle has been the flat denial of reality for quite some time now—Donald Trump is like anti–Nobel Prize they’ve won in that category—and it’s a sure thing that’s all we’ll see from them for a long time to come.

Tip o’ the bitumen to Climate Desk.

*Note Barton’s use of the phrase “Democrat party,” a term used specifically to make them sound bad. If someone uses it to start a sentence, you can be sure that the next thing they say would be useful as fertilizer.

July 11 2016 11:40 AM

Measles Outbreak in Arizona Likely Fueled by Vaccine Refusals

The largest outbreak of measles this year is occurring right now in Arizona. There have been 22 confirmed cases so far since late May. Up to that point, there were only 19 cases in the entire country in 2016.

The outbreak is attributed to the Eloy Detention Center, a privately run federal immigration detention center. This doesn’t surprise me; measles was eliminated in the U.S. in 2000, but people traveling to the U.S. (including Americans returning from foreign countries) are the biggest source of outbreaks. Disneyland was the epicenter of a measles outbreak in 2015 for just this reason.

The likely carrier in the Arizona situation was a migrant, but the problem was amplified by unvaccinated employees at the facility. The detainees have been cooperative and received vaccinations, but apparently many of the employees have been refusing or haven’t shown proof of vaccination.

It’s not clear why. Perhaps they’re simply anti-vaxxers, unable or unwilling to accept the reality that vaccines are one of the safest medical modalities available; their huge benefits far, far outweigh their very small risk. The vast majority of claims by anti-vaxxers are false. They don’t cause autism. They aren’t loaded with toxins. And on and on.

Remember too that the modern anti-vax movement started due to a discredited doctor who fraudulently connected vaccines with autism, performed unethical tests on children (!!), and had a tremendous conflict of interest. Still, it’s taken hold in various communities, and anti-vaccination tendencies have caused many outbreaks around the world, including in the U.S.

I hope this Arizona outbreak doesn’t get any worse, but measles is highly contagious and the workers who aren’t vaccinated could very easily spread it to the public at large. An infection from measles can result in high fever, but in children it can produce much more devastating complications, including permanent hearing loss, pneumonia, encephalitis, and even death. If you live in Arizona read up on the symptoms and be cautious.

Please talk to your doctor and check to see if you need your vaccination (usually given as an MMR combination with mumps and rubella). The people most at risk are infants too young to be vaccinated, and people with compromised immune systems; for example, those undergoing chemotherapy, or who have auto-immune diseases. A family member of mine has the latter, so for me this is personal. I’m up-to-date with all my shots, and so is everyone in my immediate family. We walk the walk.

Vaccines work. They wiped out smallpox globally, and polio is on its way out as well. Rubella has been eliminated in the Americas, too. Measles was stopped dead in its tracks once in this country. Let’s make it happen again.

July 11 2016 9:30 AM

An Alien Planet Orbits in a Triple-Star System … and We Have Photos

Astronomers have discovered a truly remarkable planet. Called HD 131399Ab,* it’s in a triple-star system: It orbits a star orbited by another binary pair of stars!

I know, I know: Pics or it didn’t happen, right?

Yeah, well, here you go:

photos of planet
Actual, direct images of the exoplanet HD 131399Ab. See text for description.

Wagner, et al., from the paper

Yes, those are actual images of the planet! The frames A-D show the planet (labeled “b”) at different infrared wavelengths, with the primary star’s position marked by a crosshair (the star’s light has been removed using various observational and processing techniques to better see the planet), and the larger panel E is a composite showing the star, the planet, and the binary.

There’s a lot of very cool stuff going on here, so let me explain.

As a whole, the star system is called HD 131399, and it’s what’s called a hierarchical triple: Two stars orbiting each other in a binary pair, which in turn orbits another star. The primary, most massive star is called HD 131399A, and is hotter and more massive (about 1.8 times more) than the Sun. The binary is composed of a star very much like the Sun and another star that’s cooler, redder, and less massive (0.6 times the Sun’s mass). The binary is pretty far out, orbiting the primary at a distance of about 40–60 billion kilometers. That’s about 10 times Pluto’s distance from the Sun, to give you a sense of scale.

The system is part of a loose cluster of stars called an association located roughly 300 light-years from Earth. This is important: We know, from studying those stars, that the association is young, probably around 16 million years old. Why is that important? Because when planets first form they are very hot, and it takes a long time for them to cool. The more massive a planet is, the longer it takes.

The light given off by a hot planet depends on its temperature, and as I said that depends on its mass and age. We know the age, so by examining the light from the planet, its mass can be derived. In this case, the astronomers found the planet has a mass of about four times that of Jupiter! While that’s big, it’s very firmly in the planetary mass range (even if the planet is older, and therefore more massive, it’s still very likely to be a planet and not a low-mass star or brown dwarf).

solar system to scale
Our own solar system overlaid to scale on the HD131399 system. The new exoplanet orbits its star farther out than Pluto does the Sun. Note the colors have been added for clarity and are not necessarily real.

Wagner, et al.

So how do they know it’s actually orbiting the primary star, and not a background object? I love this part: The astronomers used archived images taken over many years to measure the actual motion (what we call the proper motion) of the system. All the stars in the sky are orbiting the center of the galaxy, but that motion is hard to measure directly because stars are so far away. But some stars are close enough to us that it can be detected (it’s like driving down a road; nearby trees seem to zip past, but a distant mountain appears to pass much more slowly).

By mapping the motion of the stars and the planet, they found that the planet appears to move along with the stars across the sky, showing pretty conclusively it’s actually a member of the system. However, the motion isn’t exactly the same, and that’s because the planet is orbiting the star, and that motion is seen on top of its velocity through space!

Although it’s hard to determine the exact orbital shape and distance, it’s likely the planet is about 12 billion km from the star, and takes about 550 years to orbit it once. Even though it’s more than twice as far from the star as Pluto is from the Sun, its temperature is 575°C (1070°F), still very hot from its formation.

This makes it unique among planets seen so far: It has the widest known orbit for an exoplanet in a triple system. In fact, its orbit is so wide that it’s quite possible the gravity from the binary yanks on it. Over time, the orbit may be unstable! The astronomers ran some simulations and showed it’s about as likely the planet’s on a stable orbit as not. It’s so young that we may be seeing it before it gets ejected from the system … or it may be fine and dandy where it is for the next few hundred million years. Here’s a video animation showing what all those orbits look like:

And there’s more: As far as we know, it’s not possible to form a big planet on such a wide orbit in situ. It’s far more likely it formed much closer in, but an interaction with another massive planet (one too close to the primary to be spotted yet) flung it out to its current distant position. But there’s another possibility, which I find completely fascinating: It may have formed as a planet around the binary stars, and got flung out (either by the stars themselves or another possible planet orbiting them) to its present orbit.

If that’s the case, the planet doesn’t orbit the star(s) it formed around! How weird is that?

Incidentally, very careful observations of the planet show that its atmosphere is likely to have methane and water vapor in it, common in gas giants. It’s amazing we can tell that at all from our distance of 3,000 trillion kilometers, but exoplanet astronomers are getting pretty dang good at what they do.

And one final thing: What does the sky look like from this planet? Or, say, any moons it might have, since the planet is a gas giant.


From more than 12 billion kilometers away, the primary star would only be about 1/500th as bright as the Sun is from Earth. That’s still far brighter than the full Moon in our sky, so it would be a tiny but very bright dot. The binary stars would be much fainter, even at closest approach (depending on the exact orbit of the exoplanets, which to be fair we don’t know), and would change in brightness noticeably over the centuries as the planet orbits its primary.

The distance separating the two stars in the binary isn’t explicitly mentioned in the paper, but judging from the images I’d guess they could be split by eye from the planet. But that would change as well; the two stars orbit each other, and depending on that orbit they might get close enough together to appear as one star over the years, then pull apart over time.

I wonder. If life ever arose in such a system, would they have an easier time than we did deriving the laws of motion in the cosmos? It would be hard to argue everything revolves around their planet when a counterexample sits for all to see in the sky!

It’s fun to speculate over such matters, but this system does show us something we no longer need to speculate about, after decades of exactly that: Stars are very good at making planets, and do so under an amazing array of conditions. Planets are everywhere, even where we used to think they couldn’t be.

I’ve said it before, but it bears repeating; The Universe is more clever than we are. I wouldn’t have it any other way.

* The name comes from the star being the 131,399th entry in the Henry Draper stellar catalog. Stars in multiple systems are designated by brightness using capital letters (A, B, C, and so on), while planets are designated using the name of the star they orbit appended with a lower case letter (starting with “b” for the first planet found, then “c” and so on in order of discovery).

July 10 2016 9:30 AM

Namibian Milky Way

Our planet is gifted with a lovely atmosphere of nitrogen and oxygen, which does a terrific job of keeping us alive.

It also provides us with a very common metaphor: “Different as day and night”. And they are; during the day, sunlight passing through our atmosphere gets scattered—blue more than any other obvious color—making the sky itself appear to be blue and very bright. Contrast that with the black sky at night, dark enough that we see stars. They’re there during the day, too, but the scattered sunlight is so strong and so bright that it washes out the stars.

So how can the photo above show what looks to be the Milky Way and thousands of stars over a daylit scene?

Because it doesn’t. Yes, that’s the Milky Way, and yes, those are myriad stars, but no, it’s not daylit. It’s moonlit!

The photo was taken by photographer Florian Breuer in Namibia on June 10. It was a few hours after sunset, with the crescent Moon low in the sky. He took four 30-second exposure photos and stitched them together to make this panorama; the phenomenal dark and clear southern Africa skies allowing the glow of the stars and our home galaxy through. But the low Moon was also bright enough that, in the long exposures, the landscape was illuminated, and the tree even cast a shadow!

This is not at all how your eye sees the scene were you there, but cameras work differently than our eyes. This is something I wish more people understood; when you take a photo of something you are automatically changing how it’s seen. Colors, brightnesses, perspective, and much more are recorded in ways that alter them. So while this image may look fake, it’s not. At least, it was photographed faithfully to the scene (with minor contrast adjustments), but it’s not how it would look to us standing there.

But nothing is. This is a very important lesson in life, one I iterate whenever I post an optical illusion or eyewitness account of some oddity, but it bears repeating here, too: What you see is almost never what you get.

But that doesn’t make shots like this any less real, or any less beautiful. Breuer took a lot of photos in Namibia, and trust me, you should take a look. Our world is packed with beauty, and sometimes it takes a camera’s—and photographer’s—eye to show it to us.

July 9 2016 9:00 AM

A Gathering Storm

I was sitting in my office at home writing a post for the blog yesterday when I glanced out the window. Although the Sun was shining on my yard, the sky itself was a dark, ominous gray filling the view. Afternoon storms in Colorado are common, but this one seemed different. So I went outside to look, andthis is what I saw: