Astronomers announced on Wednesday that they had discovered a massive planet orbiting a tiny star, a bizarre pairing that has stumped scientists.

Most of the stars across the Milky Way are small red dwarfs like TOI-6894, which has only 20 percent of the mass of our Sun.

It had not been thought possible that such puny, weak stars could provide the conditions needed to form and host huge planets.

But an international team of astronomers have detected the unmistakable signature of a gas giant planet orbiting the undersized TOI-6894, according to a study in the journal Nature Astronomy.

This makes the star the smallest star yet known to host a gas giant.

The planet has a slightly larger radius than Saturn, but only half its mass. It orbits its star in a little over three days.

The astronomers discovered the planet when searching through more than 91,000 low-mass red dwarfs observed by Nasa's Tess space telescope.

Its existence was then confirmed by ground-based telescopes, including Chile's Very Large Telescope.

The James Webb space telescope is scheduled to turn its powerful gaze towards the planet in the next year, which could help uncover some more mysteries of this strange planet. (AFP)