365 Days of Astronomy - Weekly Edition

Ion engines are a mainstay of science fiction, featured in both Star Trek and Wars. But this is a very real technology, successfully used on several missions out there in the Solar System right now. How do they work and what are the limits?

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.

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.

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.

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.

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.

We're not learning that the vast majority of potentially habitable worlds out there are actually icy moons like Europa and Enceladus. Good news, there are hundreds, if not thousands of times more of them than worlds like Earth. Bad news, they're locked in ice. What have we learned about water worlds and their potential for habitability?

Welcome to episode 500 of Astronomy Cast. To celebrate this momentous occasion, we're going to look back 500 years into the past to see what we learned about the Universe. And then we're going to look 500 years into the future. Astronomy Cast celebrated their 500th episode on Sept 15-16, 2018. We broadcasted from our celebration, in front of a live audience! And we debuted our new theme music by composer, fan and friend David Joseph Wesley!

We started out Astronomy Cast with the controversal decision to de-planet Pluto. And here we are, more than a decade later, at the brink of recording our 500th episode when another big decision is coming down from the IAU: whose name goes on the concept that our Universe is expanding: Hubble or Lemaître? It’s a big deal and Pamela knows all about it.

The Milky Way has gobbled up dozens of dwarf galaxies and added them to its structure. Today we're going to look at the ongoing hunt for the wreckage of past mergers. And what we've discovered about dwarf galaxies in general.

Is it globular clusters or is it globeular clusters? It doesn't matter, they're awesome and we're here to update you on them.

Another update show, this time on the various generations of stars, let's get into it.

Our knowledge of space is starting to match up with our ability to get out there an explore it. There are several companies working on missions and techniques to harvest minerals from asteroids. What other resources are out there that we can use?

Thanks to Cassini and other spacecraft, we've learned a tremendous amount about the icy worlds in the Solar System, from Jupiter's Europa to Saturn's Enceladus, to Pluto's Charon. Geysers, food for bacteria, potential oceans under the ice and more. What new things have we learned about these places?

If there's one place we've learned more about in the last 10 years, it's Mars. Thanks to all those rovers, orbiters, landers which are flying overhead, crawling around the surface, and digging into the rich Martian regolith. What have we learned about Elon Musk's future home?