A team of astronomers reports rare evidence that two planets collided around a distant star. The discovery began when Anastasios (Andy) Tzanidakis reviewed old telescope data from 2020 and noticed that Gaia20ehk, a main‑sequence star about 11,000 light‑years away near the constellation Pupis, was behaving oddly.
Tzanidakis says the star showed three dips in brightness from 2016 and then much more chaotic changes around 2021. The team found that these dips and the later variability were not caused by the star itself. Instead, large amounts of rocks and dust passed in front of the star and intermittently blocked visible light.
At the suggestion of senior author James Davenport, the researchers examined infrared measurements and found that infrared light spiked when visible light dimmed. That opposite behaviour suggests the material was extremely hot and glowing. The group argues the debris most likely came from grazing impacts followed by a final, large collision. The dust cloud now orbits at roughly one astronomical unit, a distance similar to that between the Sun and Earth. The analysis appears in The Astrophysical Journal Letters.
Difficult words
- astronomer — a scientist who studies stars and spaceastronomers
- collide — to hit something or another object with forcecollided
- brightness — how much light an object gives or reflects
- variability — the condition of changing over time
- infrared — a type of light not visible to human eyes
- debris — broken pieces and dust left after a collision
- astronomical unit — distance roughly between Earth and the Sun
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How would you feel if astronomers told you two planets had collided? Explain why.
- What problems could large amounts of dust and rocks cause for observing stars from Earth?
- Why is it useful for researchers to compare visible and infrared measurements in this study?
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