Just when scientists believed they had a handle on how stars and planets form, along come celestial bodies that might turn existing theories on their head. In this case, around 540 planetary-mass objects roughly the size of Jupiter that are freely floating in space. Discovered in the Orion Nebula using the James Webb Space Telescope, astronomers have found they’re not tied to a star. What’s more baffling is that some of them happen to be moving in pairs. In theory, they shouldn’t exist. “There’s a fair degree of scepticism about them because the find was totally unpredicted,” says Mark McCaughrean, senior advisor for science and exploration at the European Space Agency (ESA), who worked with Samuel Pearson, also at the ESA, on the study. But they, and many others, are convinced they’re real.
To better understand the significance of this discovery, it’s important to know the established rules of star formation which take place when giant clouds of dust and molecular gas in a nebula cool, fragment and then slowly collapse under their own gravitational attraction. It’s common knowledge that the universe is filled with stars of different masses. There are relatively few large ones, but there are many more as you go to lower masses, a trend that continues into the regime of substellar objects known as brown dwarfs. The fragmentation process tends to generate more small
