The top space and astronomy stories of 2015.

The Top Space and Astronomy Stories of 2015

The Top Space and Astronomy Stories of 2015

Bad Astronomy
The entire universe in blog form
Dec. 31 2015 9:15 AM

The Top Space and Astronomy Stories of 2015

In 2015 we all <3 Pluto.


I swear I wasn’t going to do a “Top Whatevers of 2015” blog post this year, but then the Benevolent Overlords at Slate asked me to do one, and what choice do I have? They’re benevolent, but they are overlords. Plus I like them. So we went through the most fun stories of the year, and put them together in video form for your eyeballs. Enjoy.

(Note: I’ve added the transcript below the video, fully endowed with links so you can find more information and reminisce over the past annum.)



Every year seems to be a big year in space and astronomy, with new missions, amazing images, and wonderful science.

2015 was no exception … but it was specifically planetary science that stole the spotlight. The biggest news was the flyby of Pluto after a decadelong voyage by the New Horizons spacecraft, which sent back the first close-up pictures in human history of the tiny, frozen world. It turns out Pluto is surprisingly diverse, with vast, flat plains of frozen nitrogen, towering mountains of water ice rivaling the Rockies, and weird fields of pits caused by evaporating ice. It even has a sprawling flat area that looks like a heart!

Pluto and Charon
PLuto and its moon Charon, to scale in size and brightness.


Pluto’s large moon Charon held its own, too. It’s a ragged mess, like someone tore it apart and then slapped it back together again. The southern hemisphere is smoother, the northern more ragged, and there’s a dark red splotch at the north pole forbiddingly named Mordor. The coloration may be due to chemicals from Pluto that leaked away from its thin atmosphere and fell on Charon.

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  


Speaking of Pluto’s atmosphere, it has one. It’s very thin, but it’s mostly nitrogen, like Earth’s. And also like Earth, there’s enough there to scatter sunlight—and that means if you were on Pluto you’d see blue skies! But don’t bother with sunscreen. From 5 billion kilometers away, frost bite is a far bigger concern than sunburn.

In 2015, the Dawn spacecraft arrived at the protoplanet Ceres, the largest body in the main asteroid belt between Mars and Jupiter, and immediately “spotted” a mystery: Over a hundred bright spots on the surface, including a pair in the middle of a large crater that dominates the photos.

Speculation on the Internet ran freely, from ice deposits to—of course—alien bases. But further analysis of the spots shows they’re likely to be salt deposits, left over from briny water ice seeping up from the interior of Ceres. This was unexpected on the surface of the airless world and shows that the solar system still has lots of surprises for us.

A bright spot in the year.


Comets made the news, too: The Rosetta spacecraft went into orbit around the comet 67P/Churyumov-Gerasimenko in 2014, but the highest resolution images didn’t start rolling in until January 2015. They revealed a bizarre, forbidding place, with jagged cliffs, deep fissures, and sinkholes venting gas. A study of the layers of materials on the comet revealed how it got its rubber-ducky shape, too: It used to be two comets! A gentle collision stuck them together like two snowballs, forming the weird lumpy worldlet we see now.


Even more, scientists were able to receive a signal from Philae, the plucky robot lander that was thought lost when it hit the comet and failed to stick the landing. It fell to rest on its side and was silent for months until we heard back from it once again in June. The signal’s been intermittent, but scientists remain hopeful they can regain contact with it and find out more about the comet from up close.

comet 67P
Ruuber ducky comet, you're the one, who makes astronomy, so much fun.

Photo by ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

Weirdly, just as much in the news as science stuff that did happen was stuff that … didn’t happen.

The Kepler space observatory stares at 150,000 stars, looking for changes in their brightness as potential planets pass in front of them. One such star, KIC 8462852, was acting really, really weirdly. Instead a single dip in brightness like you’d expect from a planet, it had hundreds of dips. They seemed to come at random times, and some blocked an incredible 20 percent of the starlight. No planet could do that! So what was causing it?

it's aliens
I strongly suspect this guy is wrong.

This photo is an Internet meme and is everywhere. This specific instance is from Quickmeme.

One possibility—extremely unlikely, but possible—was that an advanced alien civilization was building gigantic structures around the star. Now, astronomers had lots of other explanations, but nothing seemed to quite fit, and it wasn’t much effort to check, so why not? Various telescopes and methods were deployed to see if aliens might be sending a signal our way, but no luck. The most likely explanation is a gigantic comet disrupted, creating millions of small chunks and huge clouds of gas that are blocking the star’s light.


That’s still pretty cool, but a tiny piece of me still hopes that maybe hailing frequencies are still open.

Another thing that didn’t happen in 2015 was that Mark Watney didn’t really get stuck on Mars. Well, that did happen, but only in the blockbuster movie The Martian. And while it was science fiction, a lot of it was rooted in what we really do know about Mars. NASA had a pretty big hand in developing and promoting the movie, which is why the technology looks so familiar. I can nitpick the details of the science in the movie—and I have—but I can’t argue the overall theme of the flick: Science and good ol’ human knowhow can overcome a lot of life’s obstacles … even what that obstacle is 100 million kilometers of empty space.

Rockets had an interesting year, too. Blue Origin, the rocket company owned by’s Jeff Bezos, successfully launched an uncrewed suborbital rocket into space and then brought it back down to land vertically on Earth once again—a successful step on the path to future flights.

Falcon 9
X marks the spot.

Photo by SpaceX

For the private rocket company SpaceX, 2015 had some pretty big ups and downs. In June, an attempted launch of a Falcon 9 carrying supplies to the space station resulted in complete catastrophe as a loose strut inside the rocket resulted in a tank of liquid helium rupturing, causing a complete loss of the mission. Still, SpaceX got an order from NASA to launch astronauts to the space station in 2017. They also made space history in late December when the booster for a Falcon 9 rocket was successfully relanded at Cape Canaveral after helping loft a series of satellites into space. The first stage booster landed vertically in a pitch-perfect mission that will hopefully lead the way to more reliable and less expensive access to space.

And Elon Musk, the flamboyant SpaceX CEO, made some headlines after saying he wanted to nuke the poles of Mars to create a thicker atmosphere on the planet, a prelude to colonizing it. I have my doubts that would work, but at least he’s not thinking small.

Elon Musk and the Moon
Oh, stop mooning, Elon.

Photo by 20th Century Fox Film Corp.

But Musk was also involved in the biggest news of all, a cover-up so huge it spans decades: It turns out the Simpsons’ home town of Springfield isn’t even in the United States! An episode of the venerable cartoon series featuring Musk showed him looking out a window after dinner and seeing the crescent Moon, but the crescent was facing the wrong way! That would only work if Springfield were in the Southern Hemisphere, putting lie to 26 years of TV. Unless Musk has been able to flip the Earth upside down, somehow. I wouldn’t put it past him.