For a few decades now, astronomers have theorized that stars form in swirling clouds of dust and gas. Once the star is there, the remaining clouds keep spinning slowly around it, forming a disc. Eventually, a process called "accretion" leads to many of these dust and gas particles sticking to each other. This kind of cosmic snowball effect eventually produces planets, moons and asteroids that keep spinning around the star, finally giving us a planetary system.
Now scientists have spotted this process in action through Chile's recently upgraded Atacama Large Millimeter/submillimeter Array (ALMA) telescope. The image above shows a "protoplanetary disc" spinning around a star called HL Tau, located about 450 light-years away from us in the Taurus constellation. The star is relatively young, but its surrounding cloud is already forming planetary bodies, which is clear from the rings in the cloud. Those dark rings exist because an object has formed there and is now picking up particles in its path as it spins.
"These features are almost certainly the result of young planet-like bodies that are being formed in the disk," ALMA Deputy Director Stuartt Corder said. "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."
The image above wouldn't be possible if the telescope used only visible light, but ALMA's new upgrades allow it to see light at much longer wavelengths, resulting in things like what we see here. The National Radio Astronomy Observatory calls it "the best image ever of planet formation around an infant star," and it's hard not to agree with that. It's a spectacular glimpse into how new planets come to be. The image also raises new questions for scientists, like how HL Tau's cloud is forming planets so quickly, but now that we've got telescopes that can see these things in action, we might just be able to find answers to that.