(Image credit: NASA/JPL-Caltech/University of Arizona) Scientists revisiting a mysterious signal from the south pole of Mars have suggested a new potential explanation, and it doesn't bode well for hopes of finding liquid water on the Red Planet.

KB: We asked ourselves, "what obliquity, what misalignment would Planet Nine induce in the solar system?" because it must induce some. We know that Planet Nine's orbit in inclined. As a result, when Planet Nine torques the rest of the solar system, the two sort of act as two precessing tops.

A fluffy cluster of stars spilling across the sky may have a secret hidden in its heart: a swarm of over 100 stellar-mass black holes. If this finding can be validated, it will explain how the cluster came to be the way it is - with its stars spaced light-years apart, smearing out into a stellar stream stretching across 30,000 light-years.

Astronomers have detected the most massive neutron star ever, and it almost shouldn't even exist. Neutron stars are the smallest in the universe, with a diameter comparable to the size of a city like Chicago or Atlanta. They are the leftover remnants of supernovae.