News Planetary Science In a first, astronomers spot the afterglow of an exoplanet collision Two Neptune-sized planets around a remote star may have hit each other and cast an infrared glow The collision of two exoplanets may have left behind a donut-shaped cloud of vaporized rock and water (illustrated), which cast an infrared glow visible to telescopes. Mark Garlick Share this:EmailFacebookTwitterPinterestPocketRedditPrint By Elise Cutts October 11, 2023 at 11:00 am In a solar system about 1,800 light-years from Earth, two planets smacked into one another in an impact that vaporized them both.