Bad Astronomy
The entire universe in blog form

Feb. 28 2016 9:15 AM

Why Do We Have Leap Days? 

Usually, there are only four Mondays in February. But this year’s February is weird*: It’ll have five Mondays.



It’s leap year!

A lot of folks get confused on why exactly we even have leap years. The answer is simple.

Wait! No it’s not! It’s actually a mess. But together with the good folks at Slate I have tried to simplify it for you in video form:

See? Now, in that video I skipped a few things, and rounded the numbers a lot to make it easier to grasp. If you want the details — and it’s math, so it’s fun, and you do — wait until tomorrow, and I’ll have an article up with lots of details. You’ll be glad you have an extra day this month to figure it all out.

* You know what’s weirder than having five Mondays in February? Having that first “r” in “February”.

Feb. 27 2016 9:30 AM

Saturnian Shadowplay

I love Cassini shots of Saturn that make me do a double-take.

The image above (taken on Feb. 11, 2016) is a little confusing, isn’t it? It took me a second to figure it out, but then it clicked into place. What you’re seeing is a narrow-angle shot of Saturn’s rings (seen as the lines going from the left to right at a slight upward angle). The rings aren’t opaque, but actually translucent. In this shot we can see through them to the cloud tops of Saturn below, where the rings are casting a shadow (the fainter arcs going from left to right at a downward angle)*. They’re curved because the shadows are cast onto the curved “surface” of Saturn, distorting them.


This image, taken in 2014, might help:

Saturn shadows
The rings here are seen edge-on, and look like a line bisecting the planet. The ring shadow on Saturn's cloud tops curves along with the curvature of the planet.

NASA/JPL-Caltech/Space Science Institute

Cool, eh? And all this wasn’t even the reason the newer shot was taken! If you look in the gap in the rings, just to the left of center in the image, you’ll see a tiny dot. That’s the moon Pan, the actual target of this observation! The rings and shadowplay are just happy bonuses. Pan orbits Saturn in the Encke Gap, a 325-km-wide band in the rings where Pan’s gravity has ejected most of the small icy ring particles.

Saturn is weird. Its rings are weird. Its moons are weird. Everything about it is weird.

That’s one of the reasons I love it.

Tip o' the RTG to Riding With Robots.

* Update, Feb 27, 2016: Arg! My original description was confusing, ironically. If I try to explain what I did I'll probably make it worse, so instead I just changed the description to make it more clear. If you got confused, I apologize, and to make up for it go look at this.

Feb. 26 2016 9:30 AM

Martian Weather Report: Scattered Clouds, With a Chance of Dropping Jaws

It’s another beautiful day on Mars! Highs in the lower -20s C, brisk winds from the southeast over most of Acidalia, low fog in Chryse Planitia, and upper-level orographic clouds off the Tharsis shield. Dress warmly and make sure that airlock’s tightly sealed behind you!

Oh, that Red Planet. Even after all these years part of my brain still thinks of it as relatively dead, unchanging, rocky and dusty, and just sitting there.


But that’s really unfair. A lack of liquid surface water doesn’t mean the planet is boring. It has an atmosphere, and even though it’s less than 1 percent the pressure of Earth’s at sea level, there’s enough there to support weather. Actual, real weather.

Don’t believe me? Then soak in this phenomenal animation of images of Mars taken over the course of a few days from orbit, showing the planet’s ever-changing meteorology:

The images were taken from Feb. 8–14 by the Mars Color Imager on board the Mars Reconnaissance Orbiter. This camera is designed to get wide-angle shots of the planet in order to keep track of its weather on daily, weekly, and even yearly timescales. It watches for water vapor and frost, ground ice, CO2 frost, and even ozone.

It observes the planet in two different wavelengths (colors) of ultraviolet and five in visible light. It uses what’s called a push-frame technique*; the detector is a rectangle that is very narrow in one direction but wide in the other (like a long ribbon), with the color filters bonded onto the detector itself. As MRO circles the planet, a color image of each part of Mars is built up in strips and can be assembled into a single color image. A lot of Earth-observing satellites use a similar technique (called pushbroom, using a single long strip of pixels), and it was even used on the New Horizons Pluto probe to create a psychedelic animated map of that tiny, distant world.

This technique is pretty efficient; you can build a smaller detector that saves mass, money, and time. Do you have a flatbed scanner in your house? They use this method too! Incidentally, the black regions in the animation are due to times when the orbiter shifts its angle or loses data, preventing it from seeing certain areas at different times.

I love the views it gets, especially of the volcanoes. Tharsis shield is a huge bump in the side of Mars, an uplifted region with three volcanoes along a line, and the giant Olympus Mons off to the side. As wind blows air up the sides of the mountains it cools and water vapor condenses, forming what are called orographic clouds. Living on the lee side of the Rocky Mountains here on Earth I see clouds like this all the time.

See the clouds running all along the equator? That’s called the aphelion cloud belt. The orbit of Mars is more elliptical than Earth’s, and when Mars is farthest from the Sun—the point in its orbit called aphelion, when it’s about 250 million kilometers from the Sun, compared with 150 million for Earth—it’s significantly colder than when it’s closest to the Sun (which is at a distance of about 205 million kilometers). That equatorial belt of clouds forms at aphelion, and may affect the Martian climate. As it happens, Mars is near aphelion now.

Mars map
I should've turned left at Acidalia. Click to enaresenate.

NASA/JPL-Caltech/Malin Space Science Systems

The folks who run the MARCI camera have a convenient map on their page to help you identify various geographic features. What else can you spot? You can also grab animations going back to 2007. Amazing.

And I can’t help but think: If we have this tech now, today, then it seems that the Ares 3 crew would’ve had even better forecasting equipment. Oh Mark Watney, how we failed you!

Tip o’ the spacesuit visor to Andy Britton and Kayla Iacovino.

* Correction, Feb. 26, 2016: I originally wrote that MARCI uses a pushbroom technique, but was informed by Bruce Cantor (Senior Staff Scientist at Malin Space Science Systems, which built MARCI!) that it uses multiple rows of pixels to make smaller subframes, not a single row of pixels.

Feb. 25 2016 9:15 AM

Astronomers Find Another Small Icy Body Out Past Pluto

Astronomers have found an interesting new world orbiting the Sun—no, it’s not Planet Nine, but it’s still cool. Called 2015 KH162, it’s a small(ish) object orbiting the Sun far, far past Pluto.

It’s not clear how big it is. You can figure out an object’s size if you know how far away it is (which we do) and how reflective it is, a number called its albedo. If it’s shiny it can be small and still look bright; if it’s dark it has to be much bigger to appear as bright.


Albedos can be difficult to determine, but given the albedos of other objects in that part of the solar system KH162 could be as small as 500 kilometers across, or as large as 1,000. Either way, it’s much smaller even than Pluto (which, at 2,300 kilometers, is smaller than our own Moon). It’s probably even smaller than Pluto’s moon Charon (which is 1,270 kilometers in diameter). Still, given that it’s almost certainly mostly ice and rock, it’s big enough that it’s probably close to spherical.

Judging just from its brightness, it’s probably in the Top 20 objects by size we know of so far out past Neptune. Not huge, but not just a bit of fluff, either.

The orbit of KH162 keeps it well away from the Sun. The Earth's orbit is too small to even show on this scale.


The orbit is interesting. KH162 is on a fairly elliptical orbit that’s tilted quite a bit to the plane of the solar system (the major planets all orbit the Sun in essentially the same plane; if you looked at the solar system from the side it would look flat, like a DVD seen on edge). It gets as far from the Sun as 12.5 billion km, but at its closest it’s a mere 6.2 billion km out. That’s very interesting; that means sometimes it’s closer to the Sun than Pluto gets!

Not that they’ll ever collide. KH162’s orbit is tipped enough that their paths don’t physically cross.

Seen from the side, the solar system planets' orbits form a flat disk. You can see how tilted KH162's orbit is. Pluto's (in white/gray), too.


It was first observed using a telescope on Mauna Kea in Hawaii back in May 2015. It was seen again many times over the next few months, enough times to establish an orbit — an object has to be observed many times to nail down the orbital shape, and KH162 moves so slowly that this took a while. It takes 489.6 years to orbit the Sun once.

In general objects out this far are called trans-Neptunian objects, or TNOs. There are different populations of them; for example, the Kuiper Belt is a torus-shaped region past Neptune where objects like Pluto and Eris dwell. Past that is the scattered disk, which has objects with more elliptical, tilted orbits. Over billions of years, some of these objects interacted with Neptune, and the giant planet’s gravity flung them into such orbits. I talked about this for Crash Course Astronomy:

I noticed something right away about KH162: Its orbital period is almost exactly three times the period of Neptune’s orbit (489.6 versus 164.8 years). That sort of simple ratio of orbital periods is called a resonance. This is certainly not a coincidence; resonances are common and usually the result of gravitational interactions. I talked with astronomer David Nesvorny, who studies how small objects out past Neptune interact with it, and he directed me to a paper he just published.

The details are complex, but the bottom line is that billions of years ago, there may have been lots of Pluto-size objects past Neptune as well as countless smaller ones. If so, as Neptune scattered the Pluto-size objects one by one, the big planet got a bit of a kick, too. Every time that happened it would have moved a tiny amount in its orbit (what we call migration). Eventually it kicked all those objects away, leaving just a couple (which is what we see, specifically Pluto and Eris). Due to the weird nature of orbital mechanics, many of the smaller objects in certain orbits would’ve been spared. This includes the 3:1 resonance; the orbit KH162 is in!

So it may be a survivor of Neptune’s wrath, in a lucky orbit that kept it away from the much bigger and more persuasive planet. How about that?

On the “how amazed should I be by this discovery?” scale I’d rate it somewhere around “hey, that’s pretty cool!” It’s pretty interesting. In fact, I’d say its discovery is important for two reasons. One is that we don’t know of many objects this size that far out—they’re faint, and really hard to detect. Every one we find is an important addition to the inventory, and tells us more about how the early solar system behaved.

But another reason this excites me is that it shows that there still are relatively massive objects out there left to be found. The scattered disk extends far, far past KH162, so there could be many bigger objects out in that region that are simply too faint to be found.

Yet. It’s a big sky, and we’ve only been looking for these worlds for a few years. KH162 certainly has a lot of siblings (including bigger siblings), and I have no doubt we’ll find many more. 

Tip o' the dew shield to Karl Battams and Charles Bell.

Feb. 24 2016 1:13 PM

Astronomers Solve One Mystery of Fast Radio Bursts and Find Half the Missing Matter in the Universe

For the past 15 years or so, astronomers have been collectively scratching their heads over Fast Radio Bursts, or FRBs: incredibly intense but also incredibly brief flashes of radio energy coming from seemingly random spots in the sky. They’re so fast—just milliseconds long—that it’s been very difficult to find out anything about them. Poof: They’re there, like a flashbulb going off, then they’re gone.

There’ve been more question than answers. Are they close by, or very far? What causes them? How often do they occur?


But now, after all these years, astronomers finally got the break they’ve been seeking. A new paper just published in Nature describes an FRB detected just last year, and a bit of sleuthing revealed its most critical characteristic: its distance. Turns out, it’s far away. Very far away.

The burst is called FRB 150418, so named because it was detected on April 18, 2015. It was first spotted by the Australian Parkes radio telescope as it was sweeping the sky, performing a survey to look for astronomical sources of radio waves. When the burst was detected, a rapid alert was sent out to other radio telescopes with higher resolution (and therefore able to better nail down the burst’s position on the sky). Within hours the Australian Telescope Compact Array was on it, pinpointing the burst’s location.

A day later, astronomers used the giant Subaru 8.2 meter telescope to observe that location in visible light, and found an elliptical galaxy sitting right at the burst’s position. They took spectra, determined the redshift, and found that the galaxy is a staggering 6 billion light-years away. That’s literally halfway across the visible Universe!

And right away one mystery was solved: (At least some) FRBs are not local. Not even close.

Follow-up observations found an afterglow, too, the fading light as the phenomenon decayed away. It took six days before it became too faint to detect.

What does all this mean?

host galaxy
Zooming in on the host galaxy: Parkes looked at wide sections of the sky (left), and from the top right to bottom are closer looks. At the bottom is the host galaxy, with the probable locations of the burst indicated by ellipses.

Keane et al.

The host galaxy of the FRB is an elliptical, which in general are old; no stars have formed there in a long, long time. That means whatever caused the FRB was probably not a massive star exploding as a supernova; those kinds of stars don’t live long after they’re born, and ellipticals don’t typically produce them. Also, supernovae tend to glow for weeks or months after the initial catastrophe, much longer than the weeklong FRB afterglow seen.

A more likely explanation is even more exotic: A coalescing pair of neutron stars. A neutron star is left over after a massive star explodes. The outer layers of the exploding star scream away, but the core collapses into a ultra-dense ball of quantum weirdness just a few kilometers across. If two such massive stars are a binary pair, orbiting each other, they eventually become a neutron star binary. Over billions of years, they spiral in to each other, merge, and form a black hole. The merger is incredibly violent and energetic, flinging out tremendous amounts of energy in a very short burst that may last only milliseconds.

That fits the FRB bill. And if any of this sounds familiar, that may be because there is a very close parallel here with gamma-ray bursts. They too are mysterious flashes of energy that were extremely difficult to nail down until technology got good enough to allow rapid follow-up. They were found to have afterglows, and studying those revealed them to be cosmological (very distant). There are two kinds of bursts: long duration, which can last for minutes, and short duration, which last for milliseconds … and which are thought to be due to merging neutron stars!

So it looks like at least some FRB and GRBs have something in common. More than that: They may be different flavors of the same kind of event.

But there’s more, and this part is really cool. As radio waves travel through the Universe, the ethereally thin amount of gas distributed through space changes them. The radio waves get dispersed, with higher energy (higher frequency) waves arriving a bit earlier than lower energy ones. It’s a bit like visible light passing through a prism and dispersing, creating the color spectrum, but the radio waves are dispersed in time, not space.

The amount of dispersion seen depends on how much stuff the radio waves pass through. But that doesn’t give you a distance; the source might be close by and passing through thick gas, or it might be much farther away and passing through much thinner material.

fast radio pulse
As the pulse traveled 6 billion light-years, material between galaxies dispersed it, slowing lower frequencies more than higher ones. At each frequency, you can see the pulse arriving later than the higher one above. The inset shows other physical characteristic of the pulse, including its total energy and polarization.

Keane et al.

But with FRB 150418, the distance was measured independently. With the total amount of material calculated through dispersion, and the distance known, the average density of material between us and it could be determined. This can then be compared to the current model of the Universe that predicts how much matter there should be … and they got a match!

Why is this a big deal? Because the Universe can be roughly divided into three components: dark energy (roughly 70 percent of the total mass/energy budget of the cosmos), dark matter (25 percent), and normal matter (5 percent). That last bit is us: regular old atoms, neutrons, protons, and the like. We’re very much in the minority here.

The thing is, we only see about half the normal matter in the Universe; the stuff “missing” is thought to be very hot gas distributed between galaxies but is very hard to detect. The observations of the FRB seem to show that the missing stuff isn’t so missing after all. The radio waves passed through it, were altered by it, and that change was measurable!

So, indirectly at least, the missing mass has been found.

And we’re not done yet. Once astronomers got a toehold on understanding gamma-ray bursts, we found out they come in a lot of different varieties. The story behind FRBs may be similar; lots of physical processes can create a short, powerful pulse of radio waves. We may yet find lots of different sources for this phenomenon.

And I wonder … with the recent LIGO detection of gravitational waves from merging black holes, in the not-too-distant future we may have more sensitive observatories, even some based in space that could detect gravitational waves from merging neutron stars. If that’s the case, then we’ll see a lot of fields in astronomy coming together. GRBs, FRBs, supernovae, galaxy collisions (supermassive black holes in their cores may collide as well), and more, all being observed in vastly different ways. Think of what we’ll learn!

One of the most fun aspects of science—and there are plenty to choose from—is that the mystery of yesterday is the observational opportunity of today. And the solutions we find always lead to more mysteries. Usually those are on a smaller scale once a phenomenon is first cracked, but as FRBs show us, there are still lots of undiscovered things going on in this Universe of ours. May they never end.

Feb. 24 2016 9:15 AM

Did the Universe Have a Beginning?

One of my favorite aspects about science, and astronomy in particular, is how it allows us to pursue some of the biggest questions we can think of.

Why is there something rather than nothing? How did the Universe come to be? What is its eventual fate?


A century or two ago these questions were the province of philosophy or religion. But now we have observations, evidence, and mathematical modeling that allow us to pursue the answers to these questions rigorously. They’re now in the domain of science.

Scientifically speaking, the idea that the Universe had an actual beginning is relatively new, only about a century old. Astronomers discovered that distant galaxies are moving away from us, and that implies the Universe was smaller in the past. Rewind the clock all the way, and you get to a moment where everything in the Universe—all matter, energy, even space itself—was crammed into one point. Let the clock move forward again, and you get a big bang.

We can understand pretty well what happened even a tiny fraction of a second after that moment, but the moment itself we don’t understand, and perhaps cannot understand. It’s a cloak, a shroud, where our mathematics and physics break down.

We call that moment the beginning of the Universe … but is it really?

Cosmologist (and my friend) Sean Carroll discusses this with Robert Lawrence Kuhn for a PBS TV show called Closer to Truth, and as usual does an excellent job describing what we know, and what we don’t know, about this moment.

As Sean points out, what we call the Big Bang is a placeholder, a way to hang a sign on something that, for the moment, we haven’t quite figured out. Everything after we have a decent grasp on, but at that moment we wind up dividing by 0 a lot. But cosmologists are working on it.

I want to point out something he said, to clarify it a bit. At about 1:20, he mentions that general relativity is wrong. I think he was being succinct to save time; I’m quite sure he doesn’t think it’s wrong, in the sense that it fails completely to explain how the Universe behaves.

Instead, he means it’s incomplete. General relativity makes a huge number of predictions of how things work in the Universe, and every single prediction we have tested has been shown to be true. GR (as those in the know call it) does an extraordinary job explaining things!

But. It turns out that quantum mechanics, which we also know works extremely well, makes different predictions about some things in the Universe, predictions that contradict what GR says. This is a problem.

But it doesn’t mean either theory is wrong, just that there’s something we’re missing. The best analogy is to Newton: He postulated a set of laws of motion that work extremely well, but it turns out they work only if you have low mass objects moving slowly with respect to one another. If the masses get large or velocities approach that of light, Newtonian mechanics breaks down. We need a more overarching set of rules … and those rules are described in general relativity! Newton’s laws weren’t wrong, just incomplete. GR does a better job explaining things.

So there’s likely a bigger theory that covers both quantum mechanics and general relativity, but is yet to be discovered. When someone figured that out it will be a big deal, and in fact may solve many of the problems Sean discusses about how the Universe began, and how it will end.

So, what about Sean’s idea that the Universe may not have had a beginning? Note how careful he is to say he doesn’t know (he’s a good scientist!), but he hopes it doesn’t, he hopes that there was something before our Universe. If that’s the case, we may need to expand what we think of as “the Universe.”

As is usually the case, the Universe knows what it’s doing. Our job is to figure out what it’s telling us about it.

Postscript: I talk about the Big Bang model in an episode of Crash Course Astronomy that may help you understand some of the topics Sean discussed:

I also talk about the eventual fate of the Universe as well in another episode. 

Feb. 23 2016 11:45 AM

The Two Tails of 67/P

I recently wrote about what we’ve learned from the space probe Rosetta as it’s orbited the comet 67/P Churyumov-Gerasimenko: its structure, composition, size, mass, and more.

And while the up-close-and-personal view is amazing, that’s not to say we can’t do some stuff from back on good ol’ Earth, too.


The image above shows the comet on Jan. 19. It was taken with the 2.5 meter Isaac Newton telescope on the Canary island of La Palma. The image is pretty deep, showing quite faint structures.

Most obvious is that the comet has two tails! This is common in comets. One is the gas tail, due to ice on the comet turning to gas and getting blown back by the fierce solar wind). The other is from fine grain dust that is pushed by the pressure form sunlight and falls behind the comet in its orbit.

However, that’s not what you’re seeing here! They’re both dust tails in this case—kinda—and they have very different positions in space.

The upper tail does appear to be aligned with the comet’s orbit, so that’s dust that’s been recently liberated from the solid core (called the nucleus) of 67P. But the lower tail appears thinner, and if you look carefully, you can see it actually extends a bit to the left of the comet head!

That’s a dead giveaway that we’re seeing a geometrical effect (the dust in a tail can’t get ahead of the comet). This second, lower tail isn't really a tail. It's actually larger-grain dust emitted from the comet last year, probably around March, which formed a cloud around the nucleus. Because the particles are bigger they don't get blown back as much by sunlight pressure, but the cloud does tend to flatten out over time. From Earth, this looks like a second tail, called a “neckline.”

This is all pretty interesting to me; I’ve never heard this term before with comets! When I saw the image, I just assumed one was a dust tail and the other gas, but appearances can be deceiving. I’ll note, too, that all of this is essentially invisible to Rosetta, because it’s sitting so close to the comet nucleus that it’s surrounded by this cloud; the light is spread out so much the cloud is too faint to spot.

You can learn a lot by getting as close as you can to an object, but it can help to take a step back and get an overview. Sometimes that’s what tells the tails.

Feb. 23 2016 9:00 AM

Gardasil Has Already Drastically Cut HPV Infections in Young Women

More good vaccine news! A new study published in the journal Pediatrics shows that the presence of human papillomavirus, or HPV, has dropped sharply in recent years in young American women. Why? The Gardasil vaccine.


HPV is awful. Two strains of it, HPV 16 and 18, are responsible for a staggering 70 percent of cervical cancer cases in women. HPV can also cause oral cancer, genital warts, and cancer of the vulva, anus, penis, and more. And here’s the kicker: About 80 million people in the U.S. carry HPV, with 14 million more cases every year.

But we’re fighting it, and we’re starting to win.

Specifically, in this new study they examined the presence of the virus in groups of women from before the vaccine was introduced (from 2003–06) and then after (from 2009–12). They looked for several strains of HPV, including HPV 16 and 18 (as well as HPV 6 and 11, which aren’t as dangerous but which are also prevented by Gardasil).

For young women aged 14–19, the presence of those four strains of HPV (and some others) were found to drop by an incredible 64 percent overall, and by 34 percent in women aged 20–24.

That’s terrific! And we can do better; uptake (the rate at which people get the vaccine) in the U.S. is still rather low. It should be given both to preteen boys and girls, too. I'll note my own daughter has had the full (three vaccine) course of Gardasil, and my wife and I are up-to-date on all our vaccinations, too.

The thing is, HPV is transmitted sexually, and in the currently screwed-up U.S. sexual culture, that means even talking about such things is frowned upon. That’s bad, especially when Gardasil is attacked by people across the political spectrum.* Anti-vaxxers as a group don’t like it because, well, they’re anti-vaxxers, and a lot of conservatives don’t like it because they think giving it to young girls gives them a free pass to have sex.

But this is wrong. Anti-vaxxers generally are wrong, but study after study has shown that Gardasil does not cause all the woe and damage anti-vaxxers claim (despite some mainstream scaremongering).

As for the claim about Gardasil increasing sexual activity, that’s a) ridiculous, and 2) ignores the fact that boys should get it as well. Funny how that’s never mentioned.

But it’s a common belief. Worse, a lot of conservatives have pushed hard for abstinence-only education, which has been proven categorically not to work. In fact, that type of thing (like virginity pledges) tends to increase teen pregnancies and occurrence of sexually transmitted diseases. Why? Because teenagers will have sex anyway, and if they aren’t educated about it, they get infected and/or pregnant.

If HPV had a lobby, it’d be pushing abstinence-only education.

There’s some more (tentative) good news in this case, too: President Obama cut funding for abstinence-only education in the White House FY 2017 budget. To put this in perspective, we’ve been throwing away $10 million a year on this nonsense.

The bad news here is that I have little doubt that the GOP-controlled Congress will put that money back into the budget for the Department of Health and Human Services. It’s more than just a colossal waste, it’s spending money to enforce ignorance, essentially ensuring more young Americans get pregnant and infected with horrible diseases.

When you ignore science, when you ignore reality, the consequences can be grave. We are making solid progress on a terrible virus that causes a lot of terrible diseases. But like all progress, it must be worked at, fought for. We have the science to prevent a lot of suffering. We should use it.

*One has to be careful when talking politics and anti-vaxxers. This topic isn’t strictly left or right, though a case can be made for certain groups being anti-vax due to their specific politics.

Feb. 22 2016 11:30 AM

Virgin Galactic Unveils SpaceShip Two, Too

On Friday, Richard Branson unveiled Virgin Galactic’s newest rocket plane: SpaceShipTwo, called the VSS Unity.

Virgin Galactic is one of several companies that want to take humans to space. The flight plan is pretty dramatic: a large carrier aircraft called WhiteKnightTwo will carry Unity underneath, flying to an altitude of about 15,000 meters (50,000 feet). It releases Unity, which then ignites a rocket engine and thrusts upward to a height of more than 100 kilometers—the Kármán line, the accepted-upon but arbitrary altitude where space “begins”—with passengers experiencing several minutes of microgravity as it falls upward and then back down. It then glides back down to Earth like a plane.


To be clear, this is a suborbital flight, essentially up and back down. This takes far less energy and fuel than going into orbit, which requires speeds of 25,000 kph. But oh, what a trip! It's still a voyage to space, which is exciting, and I’ll note a lot of science can be done on such trips.

SpaceShipOne, the first generation Virgin Galactic rocket plane, was a test vehicle that won the X-Prize in 2006 for going into space, landing, then going back up again in less than a week. SpaceShipTwo is much larger, designed to carry two pilots and six passengers.

This is the second SpaceShipTwo vehicle. The first was successfully tested in 2013, but in 2014 suffered a catastrophic and fatal failure. During descent, the vehicle undergoes what’s called feathering, rotating the tail and wing assembly to provide more surface area and slow the craft. However, one of the pilots accidentally unlocked the feathering mechanism prematurely; the mechanism deployed due to aerodynamic loads which then broke the vehicle apart, killing one pilot and severely injuring the other.*

Unity has been modified to prevent premature feathering. It will of course undergo extensive testing before powered flight; from what I can see Virgin Galactic has (wisely, in my opinion) not released an estimate of when that might be. Safety first. Incidentally, this is the first vehicle manufactured by the Spaceship Co., wholly owned by Virgin Galactic. The first two vehicles were built by Scaled Composites.

Harrison Ford in Unity
Virgin Galactic is now hiring experienced pilots. Don't get cocky, kid.

Virgin Galactic

Suborbital flight tickets go for $250,000. That may sound like a lot, but there are plenty of people who can afford it (more than 600 people have bought tickets already). Also, that’s less than it would cost for a suborbital rocket flight for a scientific experiment, making this competitive on the university/government research level.

Private crewed spaceflight is on the verge of becoming a real factor in space exploration. SpaceX has already put uncrewed vehicles into orbit (and resupplied the space station) as has Orbital ATK. Blue Origin has had some successful flights of their New Shepard suborbital rocket, but as usual has not made public their future plans on when they will send up a crewed mission. Sierra Nevada recently received a NASA award for uncrewed resupply missions to the space station for their Dream Chaser spacecraft. Both SpaceX and Boeing have contracts with NASA to launch astronauts to the space station as well, and that may happen as soon as next year.

There have been setbacks, to be sure, but we live in exciting times. And proverbs be damned; exciting times are when I want to live.

Correction, Feb. 22, 2016: I originally misstated that both pilots were killed, but pilot Peter Siebold survived.

Update, Feb. 22, 2016: Also, I clarified the wording; the pilot did not deploy the feathering mechanism itself, but unlocked it. 

Feb. 22 2016 9:15 AM

Plunge Into One of the Largest Star Nurseries in the Near Universe

I hope you’re sitting down, because my goal here is to reduce your brain to a small pile of gibbering goo.

Luckily, I have help. Behold, the Tarantula Nebula!

Holy WOW. This composite image by Robert Gendler and Roberto Colombari is incredibly beautiful… and it’s not even anywhere near full size here. Step one in brain destruction is to click here for the staggering 6,000 x 4,858 pixel version.