ʻOumuamua and interstellar space craft
Interesting podcast about the astronomical outlier object ʻOumuamua. Harvard Prof of Astronomy, Avi Loeb explores the idea that the object was a light-sail space craft sent from another civilization to check out earth.
His arguments seem very well positioned. I had previously assumed these ideas to be crackpot-y. He presents a theory that can be tested in a couple years when the Large Synoptic Survey Telescope comes online.
More recently than this podcast scientific counter arguments have been made. But the podcast is nevertheless interesting.