In 2014, Mike Brown and Konstantin Batygin noted the dwarf planets in the outer solar system have a statistically weird orbital distribution that can best be explained by adding a several Earth-mass planet out 12-23 times farther from the Sun than Pluto. All attempts to find this object in existing all-sky surveys have so far failed, and for a while, it has been thought we’d need to wait for the construction at the Rubin Observatory to be completed before it could be found.

Astronomers aren’t always patient, however, and a team from Yale University – Malena Rice and Gregory Laughlin – decided to see if they could boost the signal and find something using NASA’s Transiting Exoplanet Survey Satellite (TESS) data. This orbiting observatory is taking repeated images of local stars to look for potential transiting planets. While this data isn’t designed to look for a potential Planet 9, it turns out it is still super useful. 

Rice and Laughlin created software that allows them to stack the TESS images to mimic the effect of TESS tracking the sky at the rate that a Planet 9 would be moving instead of at the rate the stars are moving. In the resulting images, star trails dominate, but in a few images, faint specks also emerge, appearing unmoving, and marking the potential location of an unknown outer solar system object or a known object; they find those, too, and that confirms their software works. 

So far, this team has found seventeen potential objects in the outer solar system, and they are currently performing ground-based follow-up observations. It could be that they have found Planet 9 in this group. I really hope the reopening of so many observatories allows them to come out with their result soon.

One of my favorite parts of this is that Rice is a graduate student, once again showing us that great discoveries can come from people of all ages.

More Information

Yale University press release