Astronomy Cast Ep. 763: Interstellar Comets By Fraser Cain & Dr. Pamela Gay Streamed live Sep 8, 2025. Welcome to the first episode of our 19th season! This week we look at objects coming from other solar systems that come passing on by our Sun. During the summer hiatus the 3rd interstellar object was discovered: Comet 3I/ATLAS! So now we have 3 different interstellar interlopers to compare & contrast. What are we starting to learn about other star systems from this small sample size and how will our detection get even better? [Editor's note: HiRISE's telescope is 1/2 meter.]