Did you hear that astronomers from Harvard think that the interstellar asteroid Oumuamua was actually an alien solar sail? Is it aliens? Of course it's not aliens. But some day, it'll actually be aliens.

506: It’s not Aliens, Unless it’s Aliens Astronomy Cast 506: It’s not Aliens, Unless it’s Aliens by Fraser Cain & Dr. Pamela Gay

We’re always interested in the surface features of the planets and moons in the Solar System, but that’s only skin deep. It turns out, these worlds have an interesting inner life too. Thanks to the science of seismology, we can peer into our planet and learn how it works… inside. And we’re about to take that technology to Mars.

505: Seismology Astronomy Cast 505: Seismology by Fraser Cain & Dr. Pamela Gay

To really study something, you want to reach out and touch it. But what can you do if you're separated by a huge distance? You reach out with electromagnetic or sound waves and watch how they bounce back. Thanks to radar, sonar and lidar.

504: Radar, Lidar & Sonar Astronomy Cast 504: Radar, Lidar & Sonar by Fraser Cain & Dr. Pamela Gay

503: Gravity Mapping Astronomy Cast 503: Gravity Mapping by Fraser Cain & Dr. Pamela Gay

The Earth looks like a perfect sphere, but down here on the surface we see that there are mountains, rivers, oceans, glaciers, all kinds of features with different densities and shapes. Scientists can map this produce a highly detailed gravity map of our planet. And it turns out, this is very useful for other worlds too.

502: No Touching: Determining Composition of Worlds Remotely Astronomy Cast 502: No Touching: Determining Composition of Worlds Remotely by Fraser Cain & Dr. Pamela Gay

How do you know what something is made of if you can't reach out and touch it? How do we know what planets lights years away have in their atmosphere? What about the rocks all around Curiosity? Or the geysers coming out of Europa and Enceladus? Scientists have a few handy tricks.