The exoplanet 8 Ursae Minoris b should not exist. It orbits its host star at just half the Earth-Sun distance, and by all indications, the star should have gone through a phase in which it bloated up enough to engulf that entire orbit and then some. Yet 8 Ursae Minoris b definitely appears to exist.

There is a handful of potential explanations, none of them especially likely. The people who discovered the planet are suggesting that it survived because its host star got distracted by swallowing a white dwarf instead.

Big and hot

8 Ursae Minoris b was discovered using the radial velocity method, which watches for changes in a star’s light that occur as planets tug the star back and forth as they orbit. This tugging creates a blue shift in the light when the planet is pulling the star in the direction of Earth and a red shift when the star is pulled away from Earth.