![\"A](\"https:\/\/cdn.sci.news\/images\/enlarge13\/image_14618e-Gaia20ehk.jpg\")
<\/a><\/p>\nA planetary collision around star Gaia20ehk. Image credit: Andy Tzanidakis.<\/p>\n
Gaia20ehk is located approximately 11,000 light-years from Earth in the constellation of Pupis.<\/p>\n
It is a stable \u2018main sequence\u2019 star, which means that it should emit steady, predictable light. Yet in 2016, 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,\u201d said Anastasios (Andy) Tzanidakis, a doctoral candidate at the University of Washington.<\/p>\n
\u201cAnd then, right around 2021, it went completely bonkers.\u201d<\/p>\n
\u201cI can\u2019t emphasize enough that stars like our Sun don\u2019t do that. So when we saw this one, we were like Hello, what\u2019s going on here?\u201d<\/p>\n
The cause of Gaia20ehk\u2019s 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.<\/p>\n
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.<\/p>\n
\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 the Moon.\u201d<\/p>\n
\u201cIf 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
There are also clues that the collision resembles the one that created the Earth and the Moon about 4.5 billion years ago.<\/p>\n
The dust cloud is orbiting Gaia20ehk at roughly one astronomical unit, the same distance from the Sun to the Earth.<\/p>\n
At that distance, the material could eventually cool down enough to solidify into something similar to our Earth-Moon system.<\/p>\n
\u201cHow rare is the event that created the Earth and the Moon? That question is fundamental to astrobiology,\u201d said University of Washington\u2019s Professor James Davenport.<\/p>\n
\u201cIt seems like the Moon is one of the magical ingredients that makes the Earth a good place for life.\u201d<\/p>\n
\u201cIt 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.\u201d<\/p>\n
\u201cRight 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