NASA TELESCOPE DISCOVERS FIRST ROUGH STARLESS PLANET

Planets are pulled into orbits around stars in the same way that Earth orbits the Sun; this is how we typically think of planets in terms of solar systems. Scientists have recently started finding rogue planets, or essentially free-floating planets in space. While looking for exoplanets in space, NASA's Transiting Exoplanet Survey Satellite (TESS) found one of these planets, which are difficult to find.

Rogue planets orbiting a much larger star have, for some reason, managed to escape. Some might have formed outside of any planetary system at all, while others might have orbited a star early in their lives before being expelled. The first rogue planets discovered were massive, larger than Jupiter, the largest planet in our solar system. Since then, rogue planets that are more akin to Earth have been found. Researchers from NASA and Osaka University came to an unexpected conclusion in a collaborative study. Our home galaxy, the Milky Way, is probably home to more rogue planets than planets orbiting stars. They predict that the frequency of rogue planets in our galaxy is six times higher.

These wandering planets are small, cold, and dark because they are far from any stars. Gravitational micro-lensing is the keystone event that makes rogue planet discovery possible. When a star or planet approaches an unrelated background star closely, micro-lensing occurs. The closer object is then surrounded by light bent from the background star due to the celestial body's mass warping space-time. 

Because they are far from any stars, these wandering planets are small, cold, and dark. The primary mechanism that enables the discovery of rogue planets is gravitational microlensing. Micro-lensing is the result of a star or planet passing close to an unrelated background star. The mass of the closer object then warps space-time such that light from the background star is bent around it.