![\"Two](\"https:\/\/www.newsbeep.com\/ca\/wp-content\/uploads\/2026\/03\/collision_final.jpg\")
Lead author Andy Tzanidakis\u2019 rendering of the planetary collision he suspects occurred around star Gaia20ehk in 2021. Photo: Andy Tzanidakis<\/p>\n\t\tLead author Andy Tzanidakis\u2019 rendering of the planetary collision he suspects occurred around star Gaia20ehk in 2021. Photo: Andy Tzanidakis<\/p>\n
Anastasios (Andy) Tzanidakis<\/a> was combing through old telescope data from 2020 when he found an otherwise boring star acting very strangely. The star, named Gaia20ehk, was about 11,000 light-years from Earth near the constellation Pupis<\/a>. It was a stable \u201cmain sequence\u201d star, much like our sun, which meant that it should emit steady, predictable light. Yet this star began to flicker wildly.<\/p>\n \u201cThe star\u2019s light output was nice and flat, but starting in 2016 it had these three dips in brightness. And then, right around 2021, it went completely bonkers,\u201d said Tzanidakis, a doctoral candidate in astronomy at the University of Washington. \u201cI can\u2019t emphasize enough that stars like our sun don\u2019t do that. So when we saw this one, we were like \u2018Hello, what\u2019s going on here?\u2019\u201d<\/p>\n The cause of the flickering had nothing to do with the star itself: Huge quantities of rocks and dust \u2014 seemingly from out of nowhere \u2014 were passing in front of the distant star as the material orbited the system, patchily dimming the light that reached Earth. The likely source of all that debris was even more remarkable: a catastrophic collision between two planets.<\/p>\n \u201cIt\u2019s incredible that various telescopes caught this impact in real time,\u201d Tzanidakis said. \u201cThere are only a few other planetary collisions of any kind on record, and none that bear so many similarities to the impact that created the Earth and moon. If we can observe more moments like this elsewhere in the galaxy, it will teach us lots about the formation of our world.\u201d<\/p>\n The analysis of the star was published March 11<\/a> in The Astrophysical Journal Letters.<\/p>\n Planets form when gravity forces together matter \u2014 dust, gas, ice or rocky debris, for example \u2014 orbiting a new star. Early solar systems are chaotic \u2014 planets routinely collide and explode or go flying off into outer space. Through this process, and over perhaps 100 million years, solar systems like ours winnow their planets down and settle into an equilibrium.\u00a0<\/p>\n As common as these collisions probably are, observing one in a distant solar system requires patience and luck. The orbits of the planets must take them directly between us and their star, so that the resulting debris obscures some of the star\u2019s light. The telltale flicker then takes years to play out.\u00a0<\/p>\n \u201cAndy\u2019s unique work leverages decades of data to find things that are happening slowly \u2014 astronomy stories that play out over the course of a decade,\u201d said senior author James Davenport<\/a>, a UW assistant research professor of astronomy. \u201cNot many researchers are looking for phenomena in this way, which means that all kinds of discoveries are potentially up for grabs.\u201d<\/p>\n Tzanidakis, the study\u2019s lead author, studies extreme variability in stars over time. His previous work at the UW identified a system with a binary star and a large dust cloud that caused a seven-year eclipse<\/a>.<\/p>\n The behavior of Gaia20ehk, however, posed a new mystery. The star\u2019s particular fluctuation \u2014 short dips in brightness and then chaos \u2014 had never before been observed. The team was stumped, until Davenport suggested that they use data from a different telescope to look for infrared light rather than visible light.\u00a0<\/p>\n \u201cThe infrared light curve was the complete opposite of the visible light,\u201d Tzanidakis said. \u201cAs the visible light began to flicker and dim, the infrared light spiked. Which could mean that the material blocking the star is hot \u2014 so hot that it\u2019s glowing in the infrared.\u201d<\/p>\n A cataclysmic collision between planets would certainly produce enough heat to explain the infrared energy. What\u2019s more, the right kind of collision could also explain those initial dips in light.<\/p>\n \u201cThat could be caused by the two planets spiraling closer and closer to each other,\u201d Tzanidakis said. \u201cAt first, they had a series of grazing impacts, which wouldn\u2019t produce a lot of infrared energy. Then, they had their big catastrophic collision, and the infrared really ramped up.\u201d\u00a0<\/p>\n There are also clues that the collision resembles the one that created the Earth and moon about four and half billion years ago<\/a>. The dust cloud is orbiting Gaia20ehk at roughly one astronomical unit, the same distance from the sun to the Earth. At that distance, the material could eventually cool down enough to solidify into something similar to our Earth-moon system. Scientists like Tzanidakis and Davenport can\u2019t know for sure until the dust settles \u2014 literally \u2014 in the system. That could take a few years, or a few million.\u00a0<\/p>\n In the meantime, their discovery is a call to action to find more collisions. The powerful Simonyi Survey Telescope at the NSF\u2013DOE Vera C. Rubin Observatory will be well suited to the task when it begins its Legacy Survey of Space and Time<\/a> later this year; some back-of-the-napkin math by Davenport suggests that Rubin could find 100 new impacts over the next 10 years. That could ultimately help narrow the search for habitable worlds outside our solar system.<\/p>\n \u201cHow rare is the event that created the Earth and moon? That question is fundamental to astrobiology,\u201d Davenport said. \u201cIt seems like the moon is one of the magical ingredients that makes the Earth a good place for life. It can help shield Earth from some asteroids, it produces ocean tides and weather that allow chemistry and biology to mix globally, and it may even play a role in driving tectonic plate activity. Right now, we don\u2019t know how common these dynamics are. But if we catch more of these collisions, we\u2019ll start to figure it out.\u201d<\/p>\n For more information, contact Tzanidakis at atzanida@uw.edu<\/a> and Davenport at jrad@uw.edu<\/a>.<\/p>\n This research was funded by Breakthrough Initiatives.<\/p>\n","protected":false},"excerpt":{"rendered":"Lead author Andy Tzanidakis\u2019 rendering of the planetary collision he suspects occurred around star Gaia20ehk in 2021. Photo:…\n","protected":false},"author":2,"featured_media":438627,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[49,48,66],"class_list":["post-529652","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-ca","tag-canada","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/529652","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/comments?post=529652"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/529652\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media\/438627"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media?parent=529652"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/categories?post=529652"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/tags?post=529652"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"A](\"https:\/\/www.newsbeep.com\/ca\/wp-content\/uploads\/2026\/03\/Gaia20ehk-sky-position.jpeg\")
Star Gaia20ehk \u2014 seen here in the center of the orange crosshairs in the inset image \u2014 is roughly 11,000 light-years from Earth, near the constellation Pupis. Photo: NASA\/NSF NOIRLab<\/p>\n![\"Two](\"https:\/\/www.newsbeep.com\/ca\/wp-content\/uploads\/2026\/03\/Gaia20ehk-light-graph-1200x876.png\")
The top graph shows brightness measurements (green and yellow dots) of Gaia20ehk\u2019s brightness in the visible light spectrum. Three small dips in brightness are apparent, followed by a more chaotic overall decline. The bottom graph shows measurements (pink, black and blue dots) of the star\u2019s brightness in the infrared spectrum. The measurements show a sharp increase in infrared as the star\u2019s visible brightness declines. Photo: Tzanidakis et al.\/The Astrophysical Journal Letters<\/p>\n