How Planets Are Born

Using the powerful Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile, astronomers have captured the best image ever showing how planets are born, thereby providing a portal to our solar system's past.

The new planet in question is forming around the infant star HL Tau, located 450 light-years from Earth. And thanks to ALMA's high-resolution capabilities, the revolutionary new image shows us never-before-seen features of the birth of a planet, including a planet-forming disk with multiple concentric rings separated by gaps - a surprising find given the star's young age.

"These features are almost certainly the result of young planet-like bodies that are being formed in the disk. This is surprising since HL Tau is no more than a million years old and such young stars are not expected to have large planetary bodies capable of producing the structures we see in this image," ALMA Deputy Director Stuartt Corder said in a statement.

When stars form from the gravitational collapse of dust and gas, this surrounding cloud will collect around the star, creating a disk. According to the widely held theory, over time the disk cools and particles stick together, growing into sand, then small pebbles, larger-size rocks, eventually to become planets.

Researchers say being able to observe the first stages of planet formation around HL Tau could provide details about the birth of stars early on in the formation of the Universe, and help us understand how our own planetary system looked when it first formed over four billion years ago.

Prior to this research, images of such clarity were only seen in computer models and artist concepts. But ALMA achieves these observations through long wavelengths, meaning it can peer through dust and gas to the core of the star system. It allows for a resolution of 35 milliarcseconds - the equivalent of looking at a penny from more than 110 kilometers (68 miles) away.

"Such a resolution can only be achieved with the long baseline capabilities of ALMA and provides astronomers with new information that is impossible to collect with any other facility, including the best optical observatories," noted ALMA Director Pierre Cox.