Remember the potential "city killer" asteroid we were all freaking out about, 2024 YR4? Initially predicted with a small but unsettling chance of hitting our planet seven years from now, astronomers eventually ruled out that apocalyptic outcome once they were able to get better observations. But the saga's not over. 2024 YR4 will be back for revenge in another pass, Martin Connors, an astronomer at Athabasca University, writes in an essay for The Conversation — and there'll be others like it. As Connors explains, YR4 exhibits what's known as "orbital resonance" with Jupiter, meaning that it moves at a multiple […]