Bad Astronomy
The entire universe in blog form

April 16 2016 9:30 AM

The New World: March 2016 Is the Sixth Temperature Record-Breaking Month in a Row

October. November. December. January. February. And now March.

For the sixth month in a row, we’ve had a month that has broken the global high temperature record. And not just broken it, but shattered it, blasting through it like the previous record wasn’t even there.

According to NASA’s Goddard Institute for Space Studies, March 2016 was the hottest March on record, going back 136 years. It was a staggering 1.28°C above average across the planet.* The previous March record, from 2010, was 0.92° above average. This year took a huge jump over that.

Welcome to the new normal, and our new world.

As you can see from the map above, much of this incredible heat spike is located in the extreme northern latitudes. That is not good; it’s this region that’s most fragile to heating. Temperatures soaring to 7° or more above normal means more ice melting, a longer melting season, loss of thinner ice, loss of longer-term ice, and most alarmingly the dumping of billions of tons of fresh water into the saltier ocean which can and will disrupt the Earth’s ability to move that heat around.

What’s going on? El Niño might be the obvious culprit, but in fact it’s only contributing a small amount of overall warming to the globe, probably around 0.1° C or so. That’s not nearly enough to account for this. It’s almost certain that even without El Niño we’d be experiencing record heat.

Most likely there is a confluence of events going on to produce this huge spike in temperature—latent heat in the Pacific waters, wind patterns distributing it, and more.

And underlying it all, stoking the fire, is us. Humans. Climate scientists—experts who have devoted their lives to studying and understanding how this all works—agree to an extraordinary degree that humans are responsible for the heating of our planet.

JMA temperatures
The Japanese Meteorological Agency measured similar temperatures as GISS (though it uses a different baseline for the average). Note the trend. See a "pause"? I don't.

Japanese Meteorological Agency

That’s why we’re seeing so many records lately; El Niño might produce a spike, but that spike is sitting on top of an upward trend, the physical manifestation of human induced global warming, driven mostly by our dumping 40 billion tons of carbon dioxide into the air every year.

Until our politicians recognize that this is a threat, and a very serious one, things are unlikely to change much. And the way I see it, the only way to get our politicians to recognize that is to change the politicians we have in office.

That’s a new world we need, and one I sincerely hope we make happen.

*GISS uses the temperatures from 1951–1980 to calculate the average. The Japanese Meteorological Agency uses 1981–2010, which gives different anomaly numbers, but the trend remains the same. Realistically, the range GISS uses is better; by 1981 global warming was already causing average temperatures to rise.

April 15 2016 9:15 AM

A Tale of Three Jupiters, Part 4: Great Jupiter’s Ghost!

Three recent news stories have come out, all dealing with exoplanets—alien worlds—that have something in common with Jupiter. Part 1 was on a solitary starless exoplanet, Part 2 was about a double of our own Jupiter, and Part 3 was about a planet in a triple-star system. I was going to end it there, but then realized I could do another installment of this increasingly inaccurately named trilogy. So here’s the final chapter, appropriately enough about a planet that’s no longer there.

Thousands of years ago, a star died.

It was running out of nuclear fuel in its core, sending paroxysms throughout the star. It blew off a wind of gas and dust, material that had once been part of its outer layers. It did this again and again, until the white-hot core itself was exposed. This dense ball of compressed matter—a nascent white dwarf—emitted fierce amounts of ultraviolet light, exciting the atoms in the expelled material, causing it to glow.

Thus NGC 3242 was born, a new object from the ashes of the old.

This object is nicknamed the Ghost of Jupiter because it’s roughly the same apparent size as the planet when seen through a telescope. In fact, it belongs to a class of objects called planetary nebulae because they resemble planets in small ‘scopes.

NGC 3242 is about 1,000 light-years away, and a couple of light-years across—20 or more trillion kilometers—so it may be a tad larger than Jupiter physically.

The image above was taken by the Spitzer Space Telescope in 2013, and shows the nebula in infrared. What you see as red is actually light with a wavelength of 8 microns—10 times longer than what our eyes can see. At that wavelength, cold dust glows strongly, so you’re seeing the complex carbon and silicate molecules blown out by the star millennia ago. You can even see concentric circles; those are actually shells of material ejected whenever the star had one of its spasms as its fuel ran out.

Overall the nebula is circular (really spherical), but the inner core is noticeably elliptical. Why? Oh, this is where irony comes in quite strongly.

Hubble image of the nebula
The inner region of the nebula seen by Hubble. Much of the structure here must be due to something that spun up the dying star.

Danny LaCrue & the ESA/ESO/NASA Photoshop FITS

The noncircular inner regions of planetary nebulae were a mystery for a long time. I studied these objects for my master’s degree, in fact, and in 1990 we didn’t really know why the inner parts were shaped the way they are. In the paper we published, my adviser, Noam Soker, made an aside in one section that, at the time, was a weird claim: Perhaps the star had planets.

When it began to run out of fuel, the star expanded into a red giant. Planets close in would be consumed. They orbited faster than the star spun, so they would spin it up, making it rotate faster. Centrifugal force would flatten the ejected gas and dust, creating a more (American) football-shaped object. The outer parts of the nebula were ejected before this happened and would be more spherical.

Then an amazing thing happened: Five years later the first exoplanet orbiting a Sun-like star was found. Not only that, but it was a planet more massive than Jupiter, orbiting extremely close in to its star. Over the next few years more such “hot Jupiters” were found, and now we know they’re actually rather common.

Voilà! That likely explains the inner regions of elliptical planetary nebulae! Noam was right. At least partially; it’s also possible these stars were binary, and consumed their partner star. But massive close-in planets work too, and we know they exist.

That may very well have been the case for the central star of NGC 3242. Perhaps it had planets, maybe even a hot Jupiter making a tight orbit around it. It expanded, got spun up by the planet, and started emitting that flattened wind which formed the elliptical shape we see. As for the planet itself it would fall to the star’s center, evaporating fiercely, until it merged with the star itself, eaten by its parent.

Do you see the irony? The Ghost of Jupiter may actually very well be the ghost of a Jupiter-like planet!

And that, it seems to me, is a fitting way to end this four-part trilogy.

April 14 2016 11:45 AM

A Tale of Three Jupiters, Part 3: Jupiter’s Brother Has Three Suns

Three recent news stories have come out, all dealing with exoplanets—alien worlds—that have something in common with Jupiter. All three stories are pretty cool, and I thought it would be fun to tell each in a separate, but related post. Not only that, I can tie the planet to the post number, too; Part 1 was on a solitary starless exoplanet, Part 2 was about a double of our own Jupiter. For Part 3, it’s about a planet in a triple-star system.

In the realm of science fiction, planets orbiting binary stars are common. Heck, if you’re young and growing ever-more dissatisfied with living on a desert planet that’s the farthest from the bright center of the Universe, you can put your foot up on a rock and contemplate the double-sunset while the wind blows through your 1970s ‘do.

It turns out reality is similar (well, minus the Luke Skywalker self-pity thing). About half of all exoplanets may orbit binary stars. In fact, we’re even finding exoplanets in triple-star systems!

And a new one just joined the list. KELT-4Ab is a Jupiter-like planet orbiting one of the stars in a trinary system. A handful of others have been found before, but this one has a pretty cool story behind it.

transit
If a planet's orbit is aligned with our line of sight we see a transit (bottom), otherwise, we don't (top).

Adapted from a diagram by Greg Loughlin.

There are lots of ways to look for exoplanets. The easiest—though by no means actually easy—is using transits. If the planet orbits the star with its orbit edge-on as seen from Earth, than once per orbit the planet passes directly in front of the star. This is called a transit, and it causes the star’s light to dip a little bit. That dip can tell you the size of the planet, as well as the period (the year) and even the shape of the orbit.

Some telescopes observe stars one at a time, looking for transits. Others look at vast swaths of the heavens, observing thousands of stars at once. KELT is like that; but there’s a twist. You might expect astronomers to use some mighty telescope with a huge mirror that gulps down light.

Not in this case. KELT stands for Kilodegree Extremely Little Telescope. Yes, seriously. It’s more of a camera with a really nice lens than a telescope, able to see a field of view a staggering 26° on a side; that’s more than 3,000 times the area of the full Moon on the sky! It patiently snaps away, recording the brightnesses of thousands of stars. It can’t see very faint stars, but it makes up for that by observing so many at one time. If something interesting is seen, they can use bigger telescopes to take a better look.

KELT-4A (also known as HIP 51260 if you want to look for it in stellar catalogs) is a star in the constellation of Leo, and is roughly 700 light-years from Earth. It’s more massive and hotter than the Sun (technically, an F star), making it bright enough to see by KELT even at its great distance.

KELT detected a periodic dimming of the star, a dip in the light every three days, lasting for just about four hours. They followed up these observations using different telescopes and confirmed it: They had found a planet orbiting the star.

KELT-4Ab, as the planet is called, is a little different than what we have here in our own solar system. As I mentioned in a previous post, transits can’t give you the mass of the planet, but taking high-resolution spectra can. The team did just that and found the planet has a mass about 90 percent that of Jupiter.

The transit data gives the planet’s size, and they found it to be 1.7 times bigger than Jupiter. Why would a planet with lower mass be bigger than Jupiter?

Because it’s hot. Being so close to the parent star means it’s heated tremendously, to a temperature of more than 1,500° C! Many such planets have been found in fact, and we call them “hot Jupiters.” And what happens to a gas when you heat it up? It expands. That’s why KELT-4Ab is bigger than you might expect. It’s puffy.

STA039PE
If Luke Skywalker tried this on KELT-4b he'd be a small puff of rapidly expanding vapor.

LucasFilms

We’ve seen planets like this before. The fun part of all this started when high-resolution follow-up images were made using the huge Keck telescopes in Hawaii. It was already known that the primary star was orbited by another star, roughly 50 billion kilometers away (more than 10 times farther than Neptune is from the Sun). But the Keck images revealed a surprise: That second star is actually a tight binary, a pair of stars orbiting each other. Both are a bit lower mass and cooler than the Sun, and orbit each other at a distance of about 1.5 billion kilometers.

KELT-4
The three stars of KELT-4: A is at the bottom, with the binary B+C at the upper left. The scale bar shows half an arcsecond; for comparison, the Moon is 1,800 arcseconds across on the sky!

Eastman et al.

So KELT-4 is actually a triple star! The primary is labeled as A, the two stars in the binary B and C, and the planet is 4Ab (by convention, the first planet in a system is given the star’s name plus a lower case b label to avoid confusion). The planet takes three days to orbit star A, stars B and C orbit each other every 30 years, and the pair together orbit star A once every 3,800 years or so.

So that’s quite a system! And here’s an interesting question: How did it form? The stars were probably born together in the same cloud of gas and dust, with the binary forming orbiting the primary. We think hot Jupiters initially form farther out from the star than where we see them now, and migrate inward. That can happen as they plow through dust and debris left over around the star after it forms, but it’s possible the distant binary might have affected that as well. They’re pretty far out, but combined have more mass than the Sun does! So they may have had an impact on KELT-4Ab, and any other possible planets in that system that haven’t yet been discovered.

We’re still getting a grip on how planets form, and what subtle forces affect them. But this is still pretty new; the first exoplanet orbiting a Sun-like star was only found in 1995, after all!

But it goes to show you that the Universe is subtle, and also efficient. It seems that wherever planets can form, they do. And that is one of the most thrilling things I know.

April 14 2016 9:15 AM

Robert De Niro Defends Anti-Vax Nonsense

In late March, the Tribeca Film Festival announced it was pulling a “documentary” from their lineup. The film, called Vaxxed: From Cover-Up to Catastrophe, was a clear piece of propaganda designed to bolster anti-vaccination nonsense.

The trailer is loaded with easily debunked claims, and the producer, Andrew Wakefield, is the founder of the modern anti-vax movement. Not so incidentally, the paper he authored linking vaccines and autism was retracted, he also lost his medical license for acting unethically (really, really unethically), had a huge conflict of interest in his aim to cast doubt on the measles-mumps-rubella (MMR) vaccine, and has been accused of fraud by the British Medical Journal.

It’s very, very clear this film was going to just be more of the same tired arguments made by anti-vaxxers who rail in the face of reality.

Tribeca is run in part by actor Robert De Niro, and the film got in the lineup due to De Niro’s influence. He has a child with autism and wanted an open discussion of it.

On Wednesday, he and Tribeca co-founder Jane Rosenthal appeared on The Today Show to talk about the festival and Vaxxed. In my original article about this I praised De Niro for pulling the film. I now rescind that praise.

At the time, he said, “But after reviewing [the film] over the past few days with the Tribeca Film Festival team and others from the scientific community, we do not believe it contributes to or furthers the discussion I had hoped for.” You can watch the video here; the discussion about vaccines starts at 2:15.  

But for some reason he has completely backtracked on this. In this more recent interview he parrots quite a few false anti-vax claims and phrases, and clearly buys into the movement’s falsehoods.

For example, he says, “The movie is something that people should see. … Definitely there’s something to that movie. … There’s a lot of information about things that are happening with the CDC and the pharmaceutical companies.”

What he’s talking about is the alleged “whistleblower” who claimed the Centers for Disease Control and Prevention was lying about research into a connection between autism and vaccines. However, that’s been widely debunked. Interestingly, although the trailer of Vaxxed heavily features this conspiracy theory, the whistleblower reportedly isn’t even in the film.

De Niro goes on: “I, as a parent of a child who has autism, I’m concerned and I want to know the truth. I’m not anti-vaccine; I want safe vaccines.”

This is an old chestnut. Jenny McCarthy claims she’s not anti-vax either, and just wants safe vaccines, but then dives right into making false claims about vaccines. But the thing is, if you do that, you’re an anti-vaxxer.

And that’s what De Niro does. When the interviewer tells him that scientists have found no evidence at all of a link between autism and vaccines, De Niro responds, “It’s more complicated than that. There is a link, and [scientists are] saying there isn’t. The obvious one is thimerosal, which is a mercury-based preservative.”

Wow. First, there’s no link at all between thimerosal and autism. Second, anti-vaxxers confuse (willfully or otherwise) different mercury compounds: Methylmercury, which can build up in your system and is dangerous, and ethylmercury, which does not build up and is excreted rapidly from the body. Thimerosal is the latter.

Also, thimerosal isn’t used in any children’s vaccines anymore and hasn’t been for quite some time. It’s used in some flu vaccines, and that’s it.

De Niro mentioning this shows that he hasn’t done any real research into this problem. It sounds to me like he watched Vaxxed and maybe read a few anti-vax sites but hasn’t looked into the real scientific research on this. This is sadly very common; people hear a claim and type it into Google, and of course get links to sites supporting that claim. They don’t usually see ones that don’t (though recently Google has made some changes to make it much easier to find the real story).

And that’s the irony here. The interviewer asks him if he wanted to air the film “to start a conversation,” and De Niro says, “To shut (the conversation) down, there’s no reason to. If you’re a scientist, let’s see. Let’s hear. Everybody doesn’t seem to want to hear much about it. It’s shut down. And [to the interviewer] you guys are the ones who should be doing the investigating.”

But the investigating has been done. Over and again. And every time, when the studies are done properly, the results are the same: Autism isn’t linked to vaccines. Again, this shows De Niro hasn’t done his due diligence here.

I’m greatly saddened by De Niro’s responses. I know he’s not a doctor or a scientist, but he’s in a position where what he says carries weight; after all, by choosing to include Vaxxed in the first place “to start a conversation” he was already influencing events.

Like it or not, celebrities have influence, because their voices get heard. And his voice is given more weight because of his rightfully respected career and the fact that he is the parent of an autistic child. I’m very sympathetic to this, but you have to be careful here. Being a parent doesn’t mean you know the medical research; my wife and I are parents, and we educated ourselves first by talking to doctors as well as reading trusted sources and medical literature before deciding that we all should get our vaccines. And we have; our whole family is fully up-to-date on our vaccinations.

The anti-vaccination movement is dangerous. They are wrong in their claims, and the result is that we are seeing vaccine-preventable diseases making a roaring comeback. As one example, measles was eradicated in the U.S., but it came back in part due to low vaccinations rates. Other examples are sadly all too easy to find.

That’s why I continue to write about this. People get sick, and some die, due to entirely preventable illnesses. Many of these people are babies, the elderly, and immunocompromised. When you skip getting vaccinated, it’s not just yourself or your immediate family you put at risk. It’s everyone you come into contact with, anyone who might pick it up and/or give it to someone else who may be vulnerable to it. I have a family member who is immunocompromised, so I take this very, very seriously.

I hope Mr. De Niro does continue to look into this, and get the actual facts. Because the information he’s getting from Wakefield, from Vaxxed, and the other sources he mentioned is wrong. Very dangerously wrong.

*Update, April 14, 2016, at 10:40 a.m.: An embedded video that autoplayed De Niro’s interview with The Today Show has been removed, and this post has been updated accordingly.

April 13 2016 11:45 AM

I’m Shocked—SHOCKED—by This NASA Photo 

That big bright thing is the Sun. The other thing is not a telephone pole or a spider blowing in the breeze. It’s actually a T-38C jet, a plane capable of supersonic flight (it’s used to train astronauts, in fact).

So what’s with the streaks? Those are shock waves coming off the jet, captured using a special technique called schlieren (pronounced shleer-en; German for “streak”) photography. This technique allows the user to capture changes in air density, among other things.

So how does this work?

A shock wave happens when an object moves through a medium (air, water, whatever) faster than the speed of sound in that medium. When you compress air, say by throwing a ball, the air will pile up in front of the ball and then flow around it as the ball moves through it. The faster you throw it, the more the air gets compressed. The air flows around the ball in a gentle curve, called a bow wave (like the wave made off the bow of a boat).

On a submicroscopic scale, what’s happening is that the ball is hitting the molecules of air, and they get pushed forward into the molecules in front of them. They then bump into the molecules in front of them, and so on. The air in front of the ball gets denser.

Think of it like a wave of information. Each molecule bumps into the one in front of it, basically telling it, “Hey, I’m getting pushed from behind, so pardon me.” That wave can only move forward at the speed of sound due to the physics of molecular motion.

As long as the ball is moving slower than sound, the air in front of the ball has plenty of time to adapt to the compression—the molecules can communicate their motion to each other—and you get a relatively stable system with that bow wave of air.

But if the ball is moving faster than sound, the molecules don’t have time to adapt. The molecules get slammed into the one ahead of them faster than they can communicate, and the air can’t smoothly adapt. The molecules ahead don’t know it’s coming, so they’re “shocked” by this. There’s a big jump in pressure and density, resulting in a thin compressed shock wave moving away from the ball as the air is violently compressed in front and then expands away to the sides and behind it. The curve is straighter, less like a bow wave and more like streaks.

That shock wave can have a lot of energy in it, and it moves away from the object at the speed of sound. An airplane moving faster than sound makes a pretty strong shock wave, which you hear on the ground as a rattling BOOM (hence “sonic boom”). Funny, too: The same physics works for exploding stars, with their gas slamming into surrounding material at much faster velocities than the speed of sound. I did the math in grad school for a class, and it works on the scale of airplanes and supernovae.

shock wave 2
Another plane makes a series of shock waves off of different surfaces. Click to enmachenate.

NASA

The first A in NASA stands for Aeronautical, and one of NASA’s missions is to understand better how airplanes move through air, and make them more efficient. Schlieren photography allows researchers to easily see the shock wave patterns coming off the various bits of an airplane, and the hope is to reduce those shocks, allowing quieter and more fuel-efficient supersonic travel.

For this type of photography it helps to have a bright source behind the object traveling, and, hey, the Sun is pretty bright. The plane and camera have to be positioned just so, but this is NASA, after all. They figured that out and ran tests producing images like the one above.

I like how you can see the jet contrail behind the plane, and a little of it poking out the other side of the Sun. Had someone showed me just that left-hand part of the image my first thought would have been that it was a solar prominence! Context is everything.

I also like how, in various photos like this one, you can see the different parts of the plane making different shock waves; the nose, wings, elevator, rudder. All of these add to the problem and need to be investigated.

I’m glad NASA does research like this; you never know where it might lead, and in this case the main goal is to make transonic travel easier. Having cooled my heels on numerous airplanes flying for many, many hours at a time, this seems like a pretty good idea to me. Think of the savings just in little packets of peanuts!

April 13 2016 9:00 AM

A Tale of Three Jupiters, Part 2: A Jupiter Doppelgänger

Three recent news stories have come out, all dealing with exoplanets—alien worlds—that have something in common with Jupiter. All three stories are pretty cool, and I thought it would be fun to tell each in a separate, but related post. Part 1 went up Tuesday. For added fun, I can tie the planet to the post number, too: For Part 2, it’s a planet that’s a double of our own big brother.

In the world* of exoplanet hunting, one of the big goals is to find an Earth analogue: A planet the same mass and size of Earth, and which also receives about the same amount of light/heat from its parent star as we do. The reasoning for that is obvious enough, and we’ve found a couple that seem to be pretty close.

But that’s not the only goal. Another one would be to find other planets orbiting other stars that look much like our other planets. One reason for this is that we still don’t have a firm understanding of how our solar system evolved after it formed. Gravitational interactions between the planets would have changed their orbital positions, and it’s possible, even likely, they migrated a lot in their early years.

Plus, we just want to have more examples of planets like our own to put our solar system into context. Are systems like ours common, or rare? Do most have a few smaller and a few bigger planets, or do other systems have different distributions?

Over the years we’ve found some planets that are similar in mass to Jupiter, for example, but they orbit their stars very close in. We call these “hot Jupiters,” and they appear to be pretty common in the galaxy. But what about planets like our Jupiter: The same size and mass, and also get about the same amount of light from their star?

A few have been found, but a new one that might fit the bill is particularly exciting: It was found via the transit method.

I’ll need to explain a bit, but first, about the planet: Called Kepler-167e, it orbits the star Kepler-167, which is more than 1,000 light-years from Earth. The star is slightly less massive and cooler than the Sun, but the planet is closer in, so it receives about the same amount of heat from its star as Jupiter does from the Sun. It may have very close to the same temperature as Jupiter.

In this case, the important bit is that its diameter has been found, and it’s 130,000 kilometers across—compare that with Jupiter, which has a width of about 140,000 kilometers. Not bad.

As for its mass … well, I’ll get to that. First, David Kipping, the lead astronomer on the team that found Kepler-167e, made a short video explaining their discovery:

You can also read more about it at AstroBites, a wonderful technical blog about current astronomy news written by graduate students.

So let me get back to the planet’s mass. Here’s the problem: We can’t find it for this planet, and it’s only weakly constrained by the data. It might be as low as 0.3 times Jupiter’s mass … but it could also be as much as 50 times Jupiter’s as well. Why is that?

I need to backtrack a bit. The planet was found using data from the Kepler spacecraft. Kepler stared at about 150,000 stars, looking for a dip in starlight that could be caused by a planet orbiting the star and blocking a bit of the star’s light. These transits tell you a lot about the planet: First, that it exists at all, but also its size (determined by how much starlight it blocks) and its orbital period (by how long it takes to cross the star).

In this case, Kepler-167e blocks about 1.6 percent of its star’s light, which is how the planet’s size was found. Two transits were seen—the minimum needed to confirm its orbit—and the period determined to be 1,071 days, or just under three years (had it been much longer, Kepler might not have actually seen more than one transit, so it’s nice this planet was found at all).

transit curve for Kepler-167e
The "light curve" when Kepler-167e blocked the light from its star. That's a very clean plot!

Kipping et al., from the paper

The problem is the transit method can’t tell you the planet’s mass. That can be found by taking exacting and high-resolution spectra of the star. As the planet orbits, it tugs on the star, and the star’s light red and blue shifts (if you want more info, I’ve written about this before). That has not been done for this star, and would be difficult: The three-year orbital period of the planet means observations would have to be taken over a very long period of time.

For planets like Earth, which are solid, we can make a decent if rough guess about the mass given the size. But planets around Jupiter’s size are weird: If you start adding more mass to them, their size doesn’t change. They just get denser. So a planet with ten times Jupiter’s mass, even 50 times, won’t be that much different in diameter than Jupiter.

That’s why the mass of this planet is so poorly known. That’s too bad: A true Jupiter analogue would have about the same mass, and we just don’t know for this planet. In fact, if it’s more than about 10–13 times Jupiter’s mass, we wouldn’t even call it a planet; we’d say it’s a brown dwarf.

Still, it’s pretty cool. Even cooler, there are four other planets in the system, each orbiting much closer in and only somewhat bigger than Earth (specifically 1.6, 1.5, and 1.2 times wider). They all orbit so close to the star that they’re very hot; their temperatures are all well above the boiling point of water.

So even if Kepler-167e turns out to be very close to Jupiter in size, mass, and temperature, its home system is plenty different than ours. But that’s OK; now we have a data point on how a planet like that affects a system different than ours, and we still learn something. More data is always good, even if it’s different and not what we expect. Heck, especially so.

The next question is, how common are these Jupiter doubles? The astronomers who found this one posit there may be 10 or so in the Kepler data. They won’t be easy to find, but hopefully given time and effort they’ll turn up.

*Galaxy? Universe?

April 12 2016 11:45 AM

Guardian of the Galactic Dust

Space isn’t empty.

It may seem that way, when on average a cubic centimeter of the space between the stars — a box the size of a six-sided die — only has a single atom in it. Compare that to the Earth’s atmosphere at sea level, which has 1019 atoms per cc!

But empty it is not. That density is low, but space is big. If you have enough cubic centimeters, even those few particles start to add up. We call this material the interstellar medium, and it’s made up of gas(mostly hydrogen, but with some helium, oxygen and other elements mixed in) and dust (complex carbon molecules and tiny grains made of lots of other materials including silicates).

This material can glow. Sometimes it’s zapped by ultraviolet radiation from nearby bright stars, causing it to light up literally like a neon sign. Other times this material reflects the light of nearby bright stars.

But what if there are no nearby bright stars? It turns out this material can sill be detected. But it’s really, really hard.

But not too hard for master astrophotographer Rogelio Bernal Andreo! Behold:

April 12 2016 9:15 AM

A Tale of Three Jupiters, Part 1: A Lonely Young Jupiter Wanders the Galaxy

Three recent news stories have come out, all dealing with exoplanets—alien worlds—that have something in common with Jupiter. All three stories are pretty cool, and I thought it would be fun to tell each in a separate, but related post. Not only that, I can tie the planet to the post number, too: For Part 1, it’s a planet that is all by itself in a crowd.

Just 150 light-years away from Earth lies a clump of stars, notable because they are young, and all about the same age: just 10 million years old. That may sound ancient, but remember that our Sun is more than 4.5 billion years old, and you can see why astronomers consider these newborns.

These stars were almost certainly born together, but they’re loosely bound together. Over time the group—called an association—will dissipate.

Still, groups of stars like this are useful, because all the stars are very nearly the same age and born from the same cloud of gas and dust. This removes (or minimizes) two variables that can affect how a star ages. By studying them we can better understand the life cycles of stars.

TW Hydrae, the nearby association in question is close enough to us that it appears rather large in our sky. Because there are thousands of stars in that part of the sky, astronomers observe them to try to determine which stars might be a part of the group and which aren’t.

While surveying stars in this area, astronomers found an interesting object dubbed 2MASS J11193254–1137466 (2MASS is the name of the survey, and the numbers represent its coordinates on the sky). Right away they were interested; the object is very red, and therefore likely to have a very low mass. More massive stars are hotter and bluer. Still, it has a temperature of about 1,500°C, warm enough to glow on its own in the infrared.

A spectrum quickly revealed the object was low mass indeed: It was classified as an L7, which is on the borderline between a true star and a brown dwarf, an object too low mass and cool to sustain nuclear fusion in its core.

That’s already very interesting, but it gets better. The astronomers took spectra of the object and found it was very young. When a brown dwarf first forms, it’s very hot due to all that matter falling onto it and slamming into it. The same is true for stars, and even planets. Planets and brown dwarfs cool over time, though, and their spectra change. When an object is young, it can fool you into thinking it’s more massive than it really is because it’s hotter and bluer.

2MASS J1119 was low mass, and young. But how young? The answer to that would reveal its true mass. And the key to that was whether or not it was a member of the TW Hydrae association or not. How can you tell?

One way is through what’s called kinematic dynamics. The stars in an association tend to move through space together, so looking at their velocities is a key factor in determining membership. The astronomers found that 2MASS J1119 does indeed have a velocity consistent with the group, and by applying a sophisticated statistical technique, they found that it’s very likely to be a member.

That’s exciting! We know the age of the association—10 million years—and that can be applied in the models of how objects like 2MASS J1119 cool to determine what its actual mass is. When this was done, it turned out it’s between four and eight times Jupiter’s mass.

That’s very small indeed, far lower than a star’s mass, and even lower than what a brown dwarf is. It’s actually a planet. Not only that, but its distance was found to be somewhat less than 100 light-years away, which means it’s on the near edge of the association, and all by its lonesome.

It’s not just a planet, it’s a rogue planet! It doesn’t orbit a star, but instead wanders the galaxy alone. It may have formed on its own, or it may have formed with a star and other planets, but got ejected somehow from the system. We think that most solar systems eject as many as half their planets through gravitational encounters, so there may be as many rogue planets between the stars as there are planets orbiting them.

A few such rogue planets have been found, and one is even closer to us than 2MASS J119. But the beauty of this one is that as a member of the TW Hydrae association, we can infer more of its properties than we otherwise might, extrapolating them from the properties of its siblings in the association. This planet is a test bed for models and hypotheses for how planets form and age.

And what will happen to it? Over millions of years, it will pull away from the group, and orbit the Milky Way on its own. It will cool, and eventually grow cold over billions more years.

I can’t help but wonder … what if it had moons that formed with it, and it was able to hold on to them as it moves away? With a hot object so close by, these moons would start off warm, then their surface would grow colder with time. But tidal forces might keep their interiors warm, as our Jupiter’s moon Io does, or Saturn’s Enceladus. That moon has a liquid ocean under its surface!

It’s not at all impossible that such exomoons orbit rogue exoplanets, watery oceans under solid ice crusts, with no real star to warm their surfaces. Could life arise there? And if so, if it evolved, grew intelligent, what myths would they weave to explain their happenstance? And how would their science develop, telling them the truth about the reality of the dark skies around them?

I started off thinking that this planet was singular, lonely. Maybe its story isn’t quite so simple. 

April 11 2016 11:45 AM

Volcanic Eruption of Denial

I love the website RealClimate. Actual, working climate scientists write the articles there, and they discuss the current news about climate. They also take on the deniers, and do so in an expert and clear fashion.

I was really impressed with a recent commentary they wrote about how volcanoes are so abused by the deny-o-sphere. If you pay any attention at all to media when climate is discussed, you’ve probably heard a claim like this: “The eruption of [such-and-such] volcano put 100 times as much [pollutant or greenhouse gas] into the air as all human activity for a year!”

These claims are dead wrong; so wrong in fact that it’s difficult for me to believe that the people making them are being honest. The RealClimate article goes into the history of these claims, which is interesting in and of itself. But what I always find fascinating is how the deniers take scientific data and then dishonestly alter them to sound reasonable.

For example, volcanoes put chlorine into the atmosphere. Deniers then compare that to human outputs of chlorofluorocarbons, or CFCs, which damage the ozone layer. But even if a single volcanic eruption put out more chlorine than human activity in a year (and they generally put out far less), the chlorine is in the form of hydrochloric acid (HCl), which is water-soluble and rains out almost immediately. CFCs are much hardier molecules and stay in the atmosphere for long periods of time. Both have chlorine, but they are very different molecules, with very different behaviors, and therefore very different effects. Comparing them is shaky at best.

I always laugh ruefully when I hear deniers talking about volcanic emission of carbon dioxide, too. They tend to exaggerate it hugely; in 2015 Mike Huckabee claimed that a single volcano puts out as much climate changing gases as humans do in a century.

That’s utter crap. Volcanoes emit about 250 million tons of CO2 on average per year. Humans emit 40 billion. Billion, with a b, more than 100 times as much as volcanoes. Even a huge, catastrophic volcanic eruption emits far less CO2 than humans do in a year. What Huckabee said was just made-up nonsense. Since he clearly has no idea what he’s talking about, yet he states it as a fact, it wouldn’t be too out-of-school to say he was lying about it.

Which brings me to the point I make over and again: If global warming is such an obvious hoax, why are deniers constantly so dishonest about it? Why not present the facts as they stand, instead of lying about them, distorting them, being misleading about them, cherry-picking them, and concocting conspiracy theories about them?

Why, it’s almost as if they have no facts, no data to back up their claims, so these dirty tactics are all they can muster.

Huh.

April 11 2016 9:15 AM

No, Planet Nine Will Not Send a Wave of Earth-Destroying Comets to Kill Us All

<sarcasm> Oh good, I get to write yet another article about factually challenged fearmongering nonsense. </sarcasm>

Sigh.

Quite a few people on Twitter and Facebook pointed out this one to me. The guilty party is an article in the U.K. tabloid fish-wrappery the Sun posted on Wednesday. It had this breathless (and grossly ridiculous) headline: “Mysterious Planet Wiped Out Life on Earth Once and Could Do It Again THIS MONTH”.

Yeah, not so much. The article itself then goes on to make a series of increasingly shaky and completely wrong claims (what follows are direct quotations from the article):

  • “Planet Nine—a new planet discovered at the edge of the solar system in January—has triggered comet showers that bomb the Earth’s surface, killing all life, says Daniel Whitmire, of the University of Louisiana.”
  • “Professor Whitmire claims Planet Nine's passage through a rock laden area called the Kuiper Belt is responsible for the ‘extinction events’.”
  • “Now some are convinced there will be a collision or a near miss before the end of April.”
  • “Nemesis or Nibiru were widely dismissed as crack-pot pseudo-science—until Planet Nine was identified in January by the California Institute of Technology, in the US.”

These claims—not to put too fine a point on it—are 100 percent male bovine excrement.

First, Planet Nine has not been “discovered.” At best, astronomers Batygin and Brown found indirect evidence for the existence of a massive planet out past Neptune (as have other astronomers before them). It’s pretty interesting evidence, even compelling, but does not yet add up to a discovery.

Second, Daniel Whitmire does not make the claim that the planet (if it exists) causes extinction events. In a recent paper, he does a bit of math showing that the existence of a trans-Neptunian planet is consistent with the idea of periodic showers of comets raining down on Earth (more on this in a moment), but he does not claim it actually does this. I’m also not sure the planet he hypothesizes is consistent with the evidence presented by Batygin and Brown; some of the orbital and planetary characteristics are similar, others aren’t.

Third, he doesn’t say it “killed all life” on Earth, because that would be really, really dumb. Mass extinctions don’t kill all life on Earth, or else we wouldn’t be here. They kill many, even most, species, but not all. I’m not nitpicking; in an article apparently designed to instill fear, phrasing like that is important.

don't panic
Be a hoopy frood.

Shutterstock/Shay Yacobinski

Fourth, who exactly are these “some” people who claim there will be a collision in April? The article never says. Quite literally; the claim is made and then never followed up on. I could just as easily say, “Some say the author of the Sun article ate 300 puppies for breakfast”. As long as I (and one other person) says that sentence out loud it’s factually correct, though (presumably) not true.

Fifth, Nibiru was and still is dismissed as sheer crackpottery, whether or not Planet Nine exists. That’s because it is sheer crackpottery. The claims made about Nibiru are completely and utterly wrong, based on bad biblical and archaeological interpretations, and ruled out by an observational survey. But gee, other than that …

Nemesis—the name given to a purported faint and cool companion to the Sun—wasn’t a crackpot idea but has pretty much been ruled out over the years by better and better observations.

Sixth, again, Planet Nine has not been identified. C’mon.

Seventh, the basis of all this silliness is the idea that mass extinctions are periodic—that is, occur on a fairly regular cycle. But this periodicity may not even exist.

Cycles of extinctions have been claimed before, but they’re pretty hard to prove. The fossil record is spotty, and it’s hard to get absolute dates for them. There have been claims of a ~60 million periodicity too—I wrote about that one in my book Death From the Skies!, in fact. But these claims struggle with small number statistics, which can make periods look real when they’re not.

I’m not saying the periodicity doesn’t exist, just that it isn’t anywhere near confirmed yet—to be fair to the tabloid, in his paper Whitmire does claim these periodicities are firmly shown. But I don’t think that’s necessarily the case; I’m still pretty skeptical of it. Claims based on this periodicity need to be taken with a very large grain of salt.

So the article in the Sun is just a pile of steaming nonsense.

Not to be outdone, though, the New York Post—another birdcage liner—created an even more ridiculous video with unreferenced information basically lifted directly from the Sun article, but with bonus goofiness added. Like the Sun article, the video says Planet Nine was discovered in January, which isn’t true. Then it says Planet Nine takes 20,000 years to orbit the Sun (this time I mean our star the Sun, not the black hole of folderol the Sun), but again we don’t know that at all.

But wait! There’s more!

The video continues blithely on, saying, “Some scientists believe this is what caused the extinction of the dinosaurs.” Actually, no, that impact was most likely a one-off event, not part of a periodic shower of comets, and was likely aided by geological conditions at the time.

Then the video repeats (again, with no references or basis in reality) that Planet Nine may send killer comets our way this month. Worse, it mangles the previously mangled nonsense from the Sun, saying scientists (not just random "some" people) think it may happen again this month.

Bottom line: Planet Nine, as described by astronomers Brown and Batygin, is likely to exist but has not been found yet. It’s unlikely to cause periodic mass extinctions, which haven’t been shown to exist anyway. And it certainly won’t send a barrage of outer solar system ice our way this month.

In other words, don’t believe what you read in tabloids. Or anywhere, actually. Seek out the actual facts.

And I’ll add that this sort of doomsday-tooting fearmongering is disgusting. It’s irresponsible and mean-spirited. It erodes people’s understanding of science and needlessly scares people just so the paper can sell ads.

And the worst part? They’ll just keep on doing it.

I’ve written on this topic, many, many times before. Here’s a sample:

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