This is what happens when you shoot an incredibly high-resolution, 1 billion-pixel camera into space and instruct it to take a photo of every single star it can see.
The image above (and an easier-to-scan version below) was produced by Gaia, the European Space Agency craft whose mission is to produce an intensely detailed three-dimensional map of more than 1 billion stars in our galaxy. (That sounds like a lot, but there are likely 100 billion stars in our galaxy.)
Gaia uses a super-powerful camera and two telescopes to pinpoint the exact location of every star in the sky (by making around 70 observations of each star). It then tracks information about each star’s brightness, size, and temperature. Beyond the pretty pictures, Gaia will create a database for astronomers to learn about the motion of those stars, and could help in the search for habitable planets. Already, Gaia is generating insights: It actually found a little more than a billion stars, which was more than expected, Nature explains. That suggests the Milky Way may be larger than we thought.
You can see all billion-plus stars in this interactive data set here. It’s very cool. In this GIF, I’m using the database to zoom in on the heart of the Milky Way. So many stars!
Tracking 1 billion stars generates an enormous amount of data. Here’s how it all works:
This just-released image above is a composite based on the first year of Gaia observations, captured between July 2014 and September 2015.
You can’t see individual stars, but you can see where the stars are the most closely packed. The brightest region is in the center, known as the “galactic plane,” or what we see as the Milky Way in the night sky. When we look at the galactic plane, we’re staring toward the center of the densest region of our galaxy. “Darker regions across the Galactic Plane correspond to dense clouds of interstellar gas and dust that absorb starlight along the line of sight,” the ESA explains in a press statement.
Gaia’s work is far from over. You can see some dark arcing patterns in the photo, which are gaps Gaia still needs to work to fill in.
The image also shows a few galaxies (the big circular orbs in the photos). Perhaps you can appreciate more of the detail in this vertical crop.
Gaia is not the only project to map the cosmos in absurd detail
There are several such projects that are all producing dazzling results. Here are a few I’ve written about in the past.
First off, there’s the Sloan Digital Sky Survey III, a digitized atlas of the known universe. The full survey, which was recently released, charts a total of 1.2 million galaxies in three dimensions. That means it shows not just their locations in the sky but their distance from the Earth as well.
Here’s one image distilled from the survey. Each of these 48,741 dots represents a galaxy. Each galaxy is a collection of billions of stars. The stars themselves trap untold planets, asteroids, and possibly even life in their gravitational clutches. This image is just one-twentieth of the night sky, a mere pinprick of a window into the universe.
There’s also the APEX Telescope Large Area Survey of the Galaxy (or ATLASGAL), which has been mapping the coldest regions of the universe for the past several years. In February, the European Southern Observatory released an absolutely stunning 187-megapixel image of the entire Milky Way (see below) as seen from the Southern Hemisphere, obtained through APEX.
The survey uses a special telescope, APEX, which has a photo sensor chilled to near absolute zero. The extreme cold allows the telescope to be sensitive to the slightest changes in temperature caused by incoming cosmic radiation.
Conventional telescopes can only observe very hot, bright things like stars. But APEX is sensitive to the much dimmer light in the submillimeter range (between infrared radiation and radio waves). This allows APEX to see the dark, cold clouds of cosmic dust where stars are born.
There’s nothing quite like staring up at a completely dark night sky to inspire a sense of wonder about the universe. But this image might just rival that.