Every six months, NASA's Near-Earth Object Wide Field Infrared Survey Explorer (NEOWISE) travels halfway around the Sun, photographing everything in sight. These images create "all-sky" maps revealing the brightness and locations of millions of celestial objects every year. Now, using 18 of these sky maps, scientists have created a timelapse of the entire sky that spans over a decade.
NEOWISE was launched in 2009 to observe the sky at four infrared wavelengths. Although it operates in the same part of the spectrum as the JWST its approach is very different, capturing large areas of the sky larger than the full Moon at a time, rather than small patches in exquisite detail.
Aside from a two-year hiatus from 2011-2013, the telescope’s detectors have been capturing almost the entire sky every year since, creating a stock of images that can be compared with each other to reveal variations we might otherwise miss.
Planets, comets, and asteroids aside, the sky usually changes so slowly it’s easy to think it isn’t changing at all. “If you go outside and look at the night sky, it might seem like nothing ever changes, but that’s not the case,” said Dr Amy Mainzer of the University of Arizona in a statement. “Stars are flaring and exploding. Asteroids are whizzing by. Black holes are tearing stars apart. The universe is a really busy, active place.”
NASA has picked a few examples of the changes NEOWISE has witnessed and put them together in this video.
The original WISE mission was designed to both find inner Solar System asteroids and observe star and galaxy formation. Its achievements include the discovery of 2.5 million supermassive black holes at the heart of distant galaxies and the identification of candidates for the universe’s brightest galaxy.
Eventually, its onboard coolant ran out, making some of its original infrared observations impossible. However, NASA realized they still had a very valuable instrument in space, with detectors capable of capturing the sky at four infrared wavelengths. Renamed NEOWISE, the spacecraft’s primary role since 2013 has been to look out for asteroids and comets, discovering one particularly bright visitor to the inner Solar System before any other observatory.
However, while it is keeping an eye out for potentially hazardous space rocks, NEOWISE has continued to photograph the rest of the universe in the background. That’s how it came to spot the black hole eating a star, the fast-moving brown dwarf, and the surprisingly rapid progress in star-forming regions shown in the video above.
Some of the 260 brown dwarfs WISE and NEOWISE have spotted within 65 light-years of Earth were found by citizen scientists assisting the Backyard Worlds: Planet 9 project. The discovery of these objects close enough to be seen moving relative to more distant stars has revealed an aspect of our galactic neighborhood we barely knew.
The idea of making a time-lapse like this wasn’t part of the original WISE planning. “We never anticipated that the spacecraft would be operating this long, and I don’t think we could have anticipated the science we’d be able to do with this much data,” said NASA’s Dr Peter Eisenhardt.