In January, Konstantin Batygin, assistant professor of plantary science, and Mike Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy, announced that they had found evidence—through mathematical modeling and computer simulations—of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system.

This object, if found, would bring the total count of planets orbiting the sun back to nine, perhaps giving solace to those who were upset when Brown killed off Pluto a decade ago. From its mass to its orbit, here are some of the things Caltech astronomers are finding out about a potential Planet Nine.

  1. Planet Nine has not yet been spotted, but its existence has been inferred from its gravitational effects on objects in the outer fringe of our solar system.

2. Planet Nine is estimated to be 10 times the mass of Earth, making it likely to look like a miniature version of Neptune.

3. Its inferred orbit is, on average, 20 times farther from the sun than that of Neptune.

4. The time it takes Planet Nine to orbit the sun just once is anywhere from 10,000 to 20,000 years.

5. Planet Nine gravitationally dominates a larger region of the solar system than any other known planet.

6. Brown and Batygin think that Planet Nine likely formed in the region of Uranus and Neptune, and got ejected to the outer edge of the solar system by a too-close encounter with Jupiter.

7. It’s also possible, though, that Planet Nine is a captured rogue planet, meaning that it originated in a different planetary system, from which it was ejected, and got pulled into our solar system by the sun.

8. The Hubble Space Telescope should be able to see Planet Nine—if it can find it— though it would only be able to produce an image a few pixels across.

9. Astronomers worldwide have already begun searching their data for Planet Nine and proposing new searches to discover the object. Brown and Batygin are optimistic that Planet Nine will be found in fewer than five years.