Every two years or so, Mars lines up nicely with the Earth. It only takes two minutes to communicate with rovers, you can see the polar ice caps in a small telescope, and it’s the best time to send spacecraft to the red planet.
Our Hosts
Fraser Cain
Universe Today
Dr. Pamela Gay
CosmoQuest
Production by
- Richard Drumm, Audio Engineer
- Ally Pelphrey, Video Engineer
17 Seasons
700+ Episodes
Ep. 576: Summer Stargazing Special
It’s time, once again, for Astronomy Cast to go on hiatus. You’ve got a couple of months on your own to explore the night sky. Before we say goodbye, though, we’d like to make a few suggestions.
Ep. 575: Observing the Moon
As amateur astronomers, we curse the Moon every month. Seriously, why doesn’t someone get rid of that thing? This week, something occurred to us. What if we actually pointed our telescopes at the Moon? What would we see?
Ep. 574: Trojan Asteroids
We imagine the asteroid belt as the place where all the rocks hang out in the Solar System, but there are two huge bands of asteroids that orbit the Sun with Jupiter called the Trojans. And soon, we might actually get a chance to see them up close.
Recent Episodes
Ep. 39: Astrology and UFOs
While Pamela's away at the American Astronomical Society meeting, we brought in a special guest to help debunk some of the pseudoscience that people mistake for astronomy. Dr Steven Novella from the Skeptic's Guide to the Universe gets to the bottom of astrology and...
Ep. 38: Neutron Stars and their Exotic Cousins
Huge stars become black holes, and small stars become white dwarfs. But medium-sized stars can become neutron stars; exotic objects that overcome the nuclear force holding protons and electrons apart. What was once the size of a star is compressed down to only a few...
Ep. 37: Gravitational Lensing
Astronomers are always trying to get their hands on bigger and more powerful telescopes. But the most powerful telescopes in the Universe are completely natural, and the size of a galaxy cluster. When you use the gravity of a galaxy as a lens, you can peer right back...
Ep. 36: Gamma-Ray Bursts
Gamma ray bursts are the most powerful explosions in the Universe, releasing more energy in a few seconds than our Sun will put out in its lifetime. It's only been in the last few years that astronomers are finally starting to unravel the cataclysmic events that cause...
Ep. 35: Questions Show #4
We know there's matter, and we know there's anti-matter. If there's dark matter, is there an anti-dark matter? How come gravity can escape from a black hole? Do black holes capture dark matter? Can a moon have a moon? Can a planet have two stars? If you've had any of...
Ep. 34: Discovering Another Earth
What a week! Astronomers announced the discovery of an Earth-sized planet orbiting the nearby star Gliese 581. We talk about the technique used to discover the planet, the possibilities of finding even smaller planets, and what the future holds for finding another...
Ep. 33: Choosing and Using a Telescope
Buying your first telescope can be a nerve-wracking experience filled with buyer's remorse. This week we discuss the basics of purchasing your first binoculars and telescope. What to look for, how to clean older equipment, and how to use it for the first time. Let's...
Ep. 32: The Search for Neutrinos
Trillions of neutrinos are produced in our Sun through its nuclear reactions. These particles stream out at nearly the speed of light, and pass right through any matter they encounter. In fact, there are billions of them passing through your body right now. Learn how...
Ep. 31: String Theory, Time Travel, White Holes, Warp Speed, Multiple Dimensions, and Before the Big Bang
We get questions every week about string theory and topics popularized by science fiction. Here's the problem. There's just no evidence. Each of these is based on wonderful and well-formed mathematical equations, or wishful thinking, but they're very hard (if not...
Ep. 30: The Sun, Spots and All
It's Spring in the Northern Hemisphere, and that means the Sun is back. But it's more than just a free heat lamp for your garden, it's an incredible, dynamic nuclear reaction complete with flares, coronal mass ejections, twisting magnetic fields and the solar wind....
Ep. 29: Asteroids Make Bad Neighbors
This week we're talking about asteroids. And not just any asteroids, but Near Earth Objects. How do astronomers find these things, why are they buzzing around the Earth, what are the chances we'll actually get hit, and what would happen if we did get hit? How could we...
Ep. 28: What is the universe expanding into?
Come on, admit it, you've had this question. If the Universe is expanding from the Big Bang, what is it expanding into? What's outside the Universe? Ask any astronomer and you'll get an unsatisfying answer. We give you the same unsatisfying answer, but really explain...
Ep. 27: Questions Show #3
The questions are piling up, so it's time to get through them. We've got a great collection this week. How can our eyes collect so many photons? What's the speed of gravity? Shouldn't the light from the cosmic microwave background radiation passed us by? Episode 27:...
Ep. 26: The Largest Structures in the Universe
This week we continue the story of galaxy formation, learning how groups of galaxies come together to form the biggest structures around - galaxy superclusters. And when you look at the Universe at this scale, environment is everything. Episode 26: The Largest...
Ep. 25: The Story of Galaxy Evolution
Our Milky Way is a complex and majestic barred spiral galaxy. But 13.7 billion years ago it began, like all galaxies, from the elementary particles formed in the Big Bang. How did our galaxy grow from nothing to the hundreds of billions of stars we see today? Episode...
Ep. 24: The Fermi Paradox: Where Are All the Aliens?
We live in a mind bogglingly big Universe filled with countless stars. We know intelligent life evolved here on Earth. It must be common across the Universe, right? But if there's life out there, how come we haven't been visited by aliens yet? Why haven't we even...
Ep. 23: Counting Aliens With the Drake Equation
If you're wondering how many extraterrestrials there are in our galaxy, you just have to use a simple equation developed by astronomer Frank Drake in 1961. Just find out how many stars there are, how many support life, how many advanced societies form, and a few other...
Ep. 22: Variable Stars
Our Sun has been around for billions of years, and will last for billions more. We're lucky, it's pretty stable and regular as stars go, only changing in brightness a little now and then. But there are stars out there that change dramatically; astronomers call them...
Ep. 21: Questions Show #2
Our episode on black holes generated many many questions from listeners. We dip into this bottomless pool of questions and start dealing with them. Are really big black holes like the Big Bang? How can black holes evaporate? What would it look like to stand on a black...
Ep. 20: What We Learned from the American Astronomical Society
It's astronomical society get together time, and we send Pamela to investigate and record. Hear the latest news that will make your text books out of date. Find out where all the dark matter is collecting, the identity of Kepler's supernova, and new insights into the...