NASA announced today that its Wide-Field Infrared Survey Explorer (WISE) was unable to find "Planet X," a hypothetical, large celestial body that some scientists theorize might exist somewhere beyond Pluto. On the plus side, WISE did locate thousands new stars and brown dwarfs, so it wasn't a total waste of staring into space.

According to Kevin Luhman, who authored a paper discussing the WISE data, it's time to put dreams of Planet X to rest. "The outer solar system does not contain a large gas giant planet, or a small companion star," he said. WISE scanned the sky in infrared light but did not find an object fitting the description of Planet X — at least the size of Saturn within 10,000 astronomical units or one at least the size of Pluto within 26,000 astronomical units. 

Some scientists had hypothesized the existence of Planet X (also nicknamed "Nemesis" and "Tych") to explain the odd orbit of small, icy objects identified by astronomers. Back in 2012, researcher Rodney Gomes said that a Planet X would exert gravitational pull on objects past Neptune, and explain why they travel the way they do. Now, scientist will have to develop another theory to explain the erratic movement of such objects.

Luckily, a second study tells us that WISE has found 3,525 stars and brown dwarfs within 500 light-years of the sun, which, according to NASA, means the stars are in our own solar "backyard." Davy Kirkpatrick, co-author of a separate study discussing the findings, said "we're finding objects that were totally overlooked before."

The WISE mission looked at 750 million stars, galaxies and asteroids from 2010 to 2011, and used an object's movement to determine each object's distance from earth: 

In general, the more an object in the WISE images appears to move over time, the closer it is. This visual clue is the same effect at work when one observes a plane flying low to the ground versus the same plane flying at higher altitude. Though traveling at the same speed, the plane at higher altitude will appear to be moving more slowly. Searches of the WISE data catalog for these moving objects are uncovering some of the closest stars.

Ned Wright, a co-author of the second study, said he thinks WISE data will reveal even more unseen bodies. WISE was put into hibernation in 2011 but reactivated in 2013 and rebranded NEOWISE. The new and improved explorer will help NASA identify asteroids, comets and other near earth objects that could pose a threat to us here on Earth.