Renowned string theorist proposes new way to hunt our solar system's mysterious 'Planet 9'

Interesting idea about planet hunting for #9 here. What I note is from the arxiv report, https://arxiv.org/pdf/2005.01120.pdf "The clustering of orbits for a group of extreme trans-Neptunian objects suggests the existence of an unseen planet of mass M ∼ 5 − 10M⊕, so-called Planet 9, at a distance of ∼ 400 − 800 AU from the Sun"

I checked this site for exoplanets, 4265 confirmed,
 
Okay, I hit the button too soon :). http://exoplanet.eu/ There are 107 exoplanets with masses in the range of 5 to 10 earth masses, they are all very close to their host stars. Semimajor axis 0.0116 a.u. out to 3.94 a.u. Looking for a similar sized object in our solar system some 400 to 800 a.u. from the Sun is very intriguing when compared to the known exoplanets documented now in this mass range.
 

Latest posts