Last month astronomers released a brilliantly hued portrait of the Milky Way galaxy. Though only a sliver of sky, it’s a dreamy haze of the dense, chilly gas that spawns stars — and a testament to the sensitive powers of its parent telescope, the Atacama Pathfinder Experiment (APEX).
Perched miles above sea level in the dusty bronzes of the Chilean desert, APEX completed its survey of the galaxy using submillimeter waves, which are couched between infrared light and radio waves. The problem with detecting these waves is that they’re so faint, water vapor in our atmosphere tends to absorb them. That’s why there’s a lot of the universe left to comb with them — and why a high-elevation desert is so ideal.
The survey, combined with data from other telescopes, forms a detailed map named ATLASGAL (the APEX Telescope Large Area Survey of the Galaxy). To understand the undertaking of sky mapping, NASA’s Jet Propulsion Laboratory poses it this way: Imagine trying to map your house while sitting in your living room. You could do a pretty good job if you have a few doors open, but you wouldn’t exactly submit it to an architecture exhibition.
Looking around those creaky corners is similar to how astronomers confined on Earth have been mapping the galaxy, one chunk of sky at a time. Here’s a few things we know about our neck of the cosmos:
It would take about 100,000 years to travel from one end to the other.
Thousands of light years, that is, which sadly disqualifies the comfort of the family station wagon. It’s so gargantuan, hundreds of billions of stars call it home, and it has enough supplies to craft billions more in its cosmic scrapbook. But it also contains at least 10 times as much dark matter, which isn’t as album-friendly. That’s reflective of the universe, which is only about 5% “normal” matter, like stars, moons, dust, and anything else we can observe.
A supermassive hole is suspected to me smack dab in the middle.
Where are we in the galaxy, anyway? The Milky Way forms a spiral with four arms — two major, two minor. We’re in one of those smaller fingers called the Orion Spur, putting us at almost 25,000 light years from the center. (You can see the sun below.)
But at the middle, there’s a hefty bulge. When we look up into the night sky and see an ethereal band, we’re seeing that belly, as detailed on Space.com. We can’t see black holes, but we know they’re there because of how they effect the stuff around them — like eating a star and burping, for instance. The beast at our center is named Sagittarius A, and it has a mass equal to about four million suns.
The Milky Way is on a collision course with the nearest galaxy.
Our galaxy is always on the move. It spins, and its arms also travel through space. Our solar system, for example, revolves around the Milky Way’s center at about 500,000 miles per hour.
The Milky Way also happens to be headed straight for the nearest large galaxy, Andromeda, which is a couple of light years away. It won’t be for billions of years, but both galaxies will get big makeovers. Stars are so far apart, researchers suspect they won’t collide but rather be thrown into different orbits. So we’re safe — for now.