See the rest of TIME’s Top 10 of Everything 2013 lists here
10. The Galaxy’s Most Adorable Planet
The cosmos don’t often get cute, but when it comes to a little world that goes by the prosaic name Kepler-37b, that rule got bent just a little. Discovered by the Kepler space telescope, the planet, which orbits a star 200 million light years from Earth, is only 2,400 mi. (3,860 km) across; and while that sounds big, it’s two-thirds the size of our own tiny Mercury and just 10% larger than the moon. Finding such a pipsqueak world was not easy. Kepler detects exoplanets by looking for the slight dimming of light as they pass in front of their parent stars in the course of their orbits. But 37b is small enough that it dims that starlight by just 0.2%. The star itself, however, happens to be an unusually steady one, with little flickering in its light output—and that made the detection possible. As for life on Kepler 37b? Forget it. It’s so close to its parent star that it completes an orbit every 11 days. It is surely completely airless and blazingly hot—no place even to think of looking for biology.
9. The Coldest Place in the Universe
Think you’re having a chilly winter? Be happy you don’t live in the vicinity of the Boomerang nebula, a cloud of gas left over from an ancient star, about 5,000 light years from Earth. Scientists have always wondered about the nebula’s unusual shape—which actually looks more like a bowtie than a boomerang—and this year got their answer, using the ALMA telescope (short for the Atacama Large Millimeter/submillimeter Array) in the Chilean desert. They found that the nebula is in fact spherical, but an especially thick band of dust absorbs some of the starlight reflecting off the grains. The rest glows in a bow-tie shape. The important detail for people who like their numbers big and record-setting, however, is the temperature. Parts of the Boomerang nebula clock in at -457.7°F (-272°C). That’s about 2°F (1.1°C) above absolute zero, the coldest temperature possible according to the laws of physics. Even intergalactic space is warmer, as these things go, at -455°F (-270°C).
8. Colliding Stars Produce Gold
Again and again you hear the question from the anti-space-travel crowd. Why spend all the money to go to space when we have problems right here on Earth? Well, if all the other answers about scientific discovery and the questing human spirit don’t satisfy them, how about this? Once in a while you might be able to collect enough pure gold to make up a few Earthly moons. Gold and other heavy elements came into being late in the universe’s early development, forged mostly by the pressure and heat within stars. But gold is so exceedingly heavy, it must take something especially explosive to cook it up. A leading theory has always been collisions between dense neutron stars. In 2013, NASA’s Swift telescope spotted a burst of gamma rays 3.9 billion light years from Earth that were consistent with such a cosmic crack-up. A week later, the Hubble space telescope looked at the same spot and found a powerful concentration of infrared energy consistent with a burst of newly generated atoms with 3,000 times the mass of Earth. The signature of some of those atoms indicated they were a few moon’s-worth of pure gold. So if one collision between two stars can produce so much of the precious metal, why is it so rare? The answer is that those collisions themselves are rare, about one every 100,000 years in a galaxy like ours. Distribute that among a few hundred billion stars, and there’s just not going to be much to go around.
7. Saturn’s North Pole Hurricane
Earthly hurricanes can be bad enough, with their 150 mph (240 k/h) winds and their Gulf-spanning size. But consider Saturn, where the Cassini space probe just discovered a north pole superstorm that makes anything we’ve ever seen on Earth look like an atmospheric sneeze. Just the eye of the storm is 1,200 miles (1,900 km) in diameter; the winds exceed 330 mph (531 k/h). Cassini had already detected violent wind vortices at the pole, as did the Voyager spacecraft when it flew by in 1980 and 1981. But the Saturnian winter kept the pole turned away from the sun for the better part of 30 years and it was impossible to see exactly what was causing the disturbance. But at last Cassini got a good look as the planet’s spring began and the astronomers were stunned by the size of the tempest. The wind physics that drive a Saturn hurricane are much the same as those on Earth. But this hurricane, which has been raging for decades, clearly doesn’t require warm ocean waters for fuel the way our hurricanes do. It could, therefore, have a long and decidedly violent life ahead of it.
6. Tiny Galaxies and Dark Matter
The Milky Way has a lot of little hangers-on. Lingering at the fringes of our 300-billion-star galaxy are 160 or so much smaller galaxies, known as globular clusters, with only a million or so stars each. That seems like quite an entourage but it’s nothing compared to what’s going on 2 billion light years from Earth, at a galactic cluster known as Abell 1689, where 160,000 globular clusters have converged. Astronomers using the Hubble space telescope analyzed the distribution of Abell’s globular clusters and found that they concentrate most heavily near the center of the galactic formation. That provides clues to the behavior—and more proof of the existence—of the mysterious stuff known as dark matter, a still unidentified elementary particle that outweighs the rest of the mass in the universe by roughly six to one. Dark matter is thought to have gathered in gas and dust in the early years after the big bang, eventually leading to the formation of galaxies. If the models are correct, it should also draw smaller formations like globular clusters into the center of the heaviest collections of galaxies. And that’s precisely what happens at Abell 1689, with the tiny galaxies huddling in the heart of the larger herd of bigger ones. We may not be able to see dark matter yet, but the more we understand how it conducts itself, the less of a mystery it becomes.
5. The Great Lakes—on Titan
Moons are more than just craters and dust, and that’s especially so on Saturn’s Titan, a body that would be a fully certified planet if it were orbiting the sun on its own instead of leashed to its larger, parent world. Titan is awash in hydrocarbons—the fundamental building blocks of life–but the moon’s bitter -289º F (-179º C) temperature make it far too cold for biology to get started. Still, scientists have always been intrigued by Titan, partly because its essential chemistry makes it something of a flash-frozen version of the early, pre-biological Earth. Now, the Cassini space probe has discovered an even more Earth-like feature on Titan: a scattering of great lakes at its northernmost latitudes. The lakes are filled with liquid methane and ethane, and they even have dry aprons of material around them, like the salt deposits left at the perimeter of brackish Western lakes when some of the water evaporates. Cassini was able to see the lakes after nine years on-site, only because Titan’s 30-year winter is at last coming to an end, allowing the clouds in its northern hemisphere to part a bit. Methane lakes and three-decade winters? No wonder life gave Titan a pass.
4. Chris Hadfield, the Singing Astronaut
We learned nothing at all about astronomy, orbital physics or human biology in space when Canadian astronaut Chris Hadfield performed his cover of David Bowie’s Space Oddity aboard the International Space Station. And who cares? Hadfield had already made himself a huge cult figure with his prodigious Tweeting, photographing and performing in space. But it was Space Oddity that made him a global figure, with more than 19 million YouTube views so far. What is its appeal? The views from space, surely. The nifty look at the inside of the space station too. And the man can handle a guitar. But that’s just the obvious stuff. Space, to most of us, is a wholly alien place—one that other people visit. When it becomes a place of music, reverie, simple, happy playfulness, it becomes humanized, even poeticized. Hadfield’s song did all that—and in a sense it made space more real and familiar than it’s ever been.
3. Twenty Billion Earths
The galaxy became a lot less lonely this year, thanks to a discovery by the Kepler space telescope, which has been in space since 2009, doing a single, rather prosaic job: scanning the cosmos and taking the census of the number of planets orbiting distant stars. Just a generation ago, we couldn’t be sure that any such exoplanets existed, now Kepler has spotted 3,538 of them—though most still must be confirmed. The question was: how many of them are roughly the size of Earth, orbiting stars like our sun at a distance that would allow water to exist in a liquid state—the sine qua non for life as we know it? In November, a team of scientists arrived at the answer, and it’s head-spinning: there are approximately 20 billion earth-like worlds in the Milky Way. That conclusion took some extrapolation, of course. Kepler’s range of vision takes in only about 150,000 stars in a galaxy that has about 300 billion of them. Within that tiny footprint of space, the satellite has so far found 10 planets that meet the criteria for Earthiness. Factoring up and adding some statistical secret sauce to the equations yielded the 20 billion figure. It’s inferential science, but probably reliable. Earth, you’re not as special as you thought.
2. The Chelyabinsk Meteor Strike
The people of Celyabinsk likely had a lot on their minds on the morning of Feb. 15, 2013—most of it having to do with getting to work. What they surely weren’t considering was that a 10-ton asteroid was hurtling toward them, moving at 41,000 mph (67,000 k/h) and packing an explosive punch of 500 kilotons—or 20 to 30 times the power of the Hiroshima bomb. But they definitely knew it when the rock exploded 14.5 miles (23.3 km) above ground, injuring 1,491 people and damaging 7,200 buildings. It was that high altitude that preventedthe meteor from doing true Hiroshima-scale damage (and there of course would have been no radiation no matter what). But the emotional fallout was serious all the same. The solar system is and always has been a shooting gallery, with free-flying rocks everywhere. NASA and other agencies around the globe do a remarkable job of spotting, cataloguing and tracking them. That can help us prepare for their approach and, one day, deflect or destroy them en route. But nothing can prevent a rogue rock from sometimes slipping in under the radar. This year, one did, and we all got a little smarter—if a lot more nervous—as a result.
1. Voyager 1 Officially Leaves Solar System
The Voyager 1 spacecraft did nothing this year that it hasn’t been doing pretty much every day since its launch from Earth in 1977—which is to say traveling out and away at about 35,000 mph (56,000 k/h). But in 2013 everything nonetheless changed, when mission analysts announced that the ship had at long last left the solar system, becoming the first human-built object to set sail in the true deep waters of interstellar space. Just what the official exit ramp of the solar system would be was always open to question. The outer boundary of the solar system is defined by where the sun’s effects—in the form of the solar wind, the storm of charged particles that stream from it—are no longer felt. That transition point is known as the heliopause—but it’s not a clean line like an earthly border. Rather it’s a swirling, turbulent region, where interstellar particles collide and mix with ones from within the solar system. The key is when the lingering particles from the sun align with the interstellar magnetic field, and an increase in interstellar cosmic rays is detectable. That, as it turned out, happened in 2012, but it took a year of study to analyze and confirm the data. The confirmation has now been made, and Voyager 1 is well and truly gone. Its on-board nuclear power generator gives it about 15 more years life—which means 15 more years we can communicate with it. After that, it will be a silent message in a bottle floating among the stars for eternity.
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