Astronomers are bewildered by a planet that shouldn't exist. We know of hundreds planets orbiting red giant stars.
The one in question is Planet Halla, in orbit of the star Baekdu, which was discovered in 2015 a team of Korean astronomers.
In research published today, scientists explain that Halla should have been engulfed by Baekdu becaues the star is burning helium.
Dr Daniel Huber is an astronomer and Senior Lecturer at the University of Sydney. He talks to Jesse.