Planetesimals are comets and asteroids and other celestial objects including Pluto. The Oort cloud is a disc of billions of planetesimals surrounding our solar system. The Milky Way galaxy is estimated to have 400 billion stars with their own orbiting planets and clouds, and the observable universe has over 2 trillion galaxies in it.

Despite this incalculable number of interstellar objects, comets from outside our own system have not been detected until recently, thanks to larger, stronger telescopes. The first was Oumuamua in 2017 and the second Borisov in 2019; and both events allowed the media to lose their shit printing nonsense articles about aliens.

On July 1 a third body was discovered by the Asteroid Terrestial-impact Last Alert System in Rio Hurtado in Chile. Named 3I/ATLAS, it’s estimated to be 20 kilometres wide. It will travel through our system at the ridiculous speed of 60 km/s relative to the Sun, and will make its closest approach in late October 2025, passing just inside the orbit of Mars.

CREDIT
ESA / Las Cumbres Observatory

ACKNOWLEDGEMENTS
M. Devogele, T. Santana-Ros, M. Micheli, F. Ocaña, L. Conversi

It hasn’t been given a cute name as far as I can see, but prepare yourself for more filler articles conforming to Betteridge’s Law.

Take care of yourselves today and try to have a good one!