Hubble’s greatest discoveries: protoplanetary discs

Our understanding of protoplanetary discs, or proplyds, exploded with a breakthrough from the Hubble Space Telescope.

Close-up of proplyds in Orion © C.R. O'Dell/Rice University; NASA
Close-up of proplyds in Orion © C.R. O’Dell/Rice University; NASA

Looking like little islands, these flat discs of cold dust and gas are left over from the formation of a new star in the Orion nebula. Although part of this material will be lost over time, some will eventually clump together in pebble-sized grains before potentially building up to form a baby planet. As such, they are known as protoplanetary discs, or ‘proplyds’.


By learning about proplyds, astronomers hope to find out more about the formation of Earth and the other planets. “This what our Solar System looked like in its infancy,” says Prof C Robert O’Dell, who made this image.

Ground-based telescopes had previously detected the objects, which were initially believed to be stars. The idea that they were discs of material surrounding the star goes back to the 1700s, but confirmation didn’t come until the late 1980s when astronomers managed to detect the disc through observations of its molecules.

The Hubble Space Telescope provided the breakthrough – directly imaging numerous proplyds for the first time within the Orion nebula.

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