http://www.astronomycast.com Astronomy Cast brings you a weekly fact-based journey through the cosmos. en-us Fraser Cain and Dr. Pamela Gay Mon, 18 Aug 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-103-electromagetism/ Our series on the basic forces of the cosmos continues! Last week we discussed gravity, and this we'll handle electromagnetism. Electricity and magnetism are just two aspects of the same force, and you can't talk about astronomy without understanding these two keys aspects of physics. Mon, 25 Aug 2008 00:00:00 GMT http://www.astronomycast.com/physics/ep-102-gravity/ You seem to like a nice series, so here's a new one we've been thinking about. Over the course of the next 4 weeks, we're going to cover each of the basic forces in the Universe. And this week, we're going to start with gravity; the force you're most familiar with. Gravity happens when masses attract one another, and we can calculate its effect with exquisite precision. But you might be surprised to know that scientists have no idea why gravity happens. Mon, 18 Aug 2008 00:00:00 GMT http://www.astronomycast.com/space-flight/ep-101-advanced-propulsion-systems/ Last week we talked about rockets. How they work and their limitations. This week we're going to look at the future of propulsion systems. From the ion engines that are already working to explore the Solar System to the prototype solar sails to futuristic technologies like magnetic sails, and bussard ramjets. This is how we'll travel to other stars. Mon, 11 Aug 2008 00:00:00 GMT http://www.astronomycast.com/space-flight/ep-100-rockets/ To move around in space, you need some kind of propulsion system. And for now, that means rockets. Let's learn the underlying science of rockets, and how they work. And learn why a rocket will never let us reach the speed of light. Mon, 4 Aug 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/galaxies/ep-99-the-milky-way/ The Milky Way is our home. An island of stars in a universe of other galaxies. But you might be surprised to learn that astronomers have only known the Milky Way's true nature for just a century. Let's learn the history of discoveries about the Milky Way, and what today's science tells us. And let's peer into the future to learn the ultimate fate of our galaxy. Mon, 28 Jul 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/galaxies/ep-98-quasars/ Last week we talked about galaxies in general, and hinted at the most violent and energetic ones out there: active galaxies. Quasars have been a mystery for half a century; what kind of object could throw out more radiation than an entire galaxy? A black hole, it turns out, with the mass of hundreds of millions of suns performs this feat. Let's trace back the history of quasars, how they were first discovered and puzzled astronomers for so long. And let's look at what we know today. Mon, 21 Jul 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/galaxies/ep-97-galaxies/ This week we're going to look at some of the biggest objects in the Universe: galaxies. It was the discovery of galaxies in the early 20th century that helped astronomers realize just how big the Universe is, and how far away everything is. Let's learn how galaxies formed and how they evolve and change over time, merging with the neighbors. And what the future holds. Mon, 14 Jul 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/planets/our-solar-system/ep-96-humans-to-mars-part-3-terraforming-mars/ And now we reach the third part of our trilogy on the human exploration and colonization of Mars. Humans will inevitably tire of living underground, and will want to stretch their legs, and fill their lungs with fresh air. One day, we'll contemplate the possibility of reshaping Mars to suit human life. Is it even possible? What technologies would be used, and what's the best we can hope for? Mon, 7 Jul 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/planets/our-solar-system/ep-95-humans-to-mars-part-2-colonists/ After astronauts make the first tentative steps onto the surface of Mars, a big goal will be colonization of the Red Planet. The first trailblazers who try to live on Mars will have their work cut out for them, being in an environment totally hostile to life. What challenges will they face, and how might they overcome them? Mon, 30 Jun 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/planets/our-solar-system/episode-94-humans-to-mars-part-1-scientists/ We're learned about the failed missions to Mars in the past, and the current spacecraft, rovers and landers currently exploring the Red Planet. But the real prize will come when the first human sets foot on Mars. Robots are cheaper, but nothing beats having a real human being on the scene, to search for evidence of water and life. Mon, 23 Jun 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/planets/our-solar-system/ep-93-missions-to-mars-part-2/ I know last week was a bit of a dry history lesson, but we wanted to give you some understanding of past efforts to explore Mars. Now we'll look at the missions currently in orbit, and crawling around the surface of Mars, and help you understand the science that's happening right now. Mon, 16 Jun 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/planets/ep-92-missions-to-mars-part-1/ With last month's safe arrival of the Phoenix Mars Lander, Mars enthusiasts breathed a collective sigh of relief… phew. Now it's time to search for evidence of organic molecules in the ice at Mars' north pole. But this is just the latest in a long series of missions sent to the Red Planet. Let's have a history lesson, and look back at the missions sent to Mars, successful and unsuccessful. Mon, 9 Jun 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/planets/our-solar-system/ep-91-the-search-for-water-on-mars/ With the successful touchdown of the Phoenix Lander, NASA is continuing its quest to find evidence of past and present water on Mars. This week we discuss the geologic history of Mars, and explain why NASA thinks the story of water on Mars is so important. And how this ties into the search for life on the Red Planet. Mon, 2 Jun 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-90-the-scientific-method/ You've heard us say it 90 times: "How we know what we know." But how do we know how we know what we know? So astronomers like all scientists use the scientific method. Without the scientific method we'd probably still think the Earth is flat, only a few thousand years old and the center of the universe. But with the scientific method everything changes. From biology, to chemistry, to physics, to astronomy it is impossible to count the number of changes that have happened to human society because of changes brought about from the scientific method. In this episode we tell you about what the scientific method is, how you can use it to improve your life, and discuss why gravity isn't just a theory. Mon, 26 May 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-89-adaptive-optics/ Since the dawn of humanity, astronomers have wished to destroy the atmosphere. Oh sure, it's what we breathe and all, but that stupid atmosphere is always getting in the way. Since destroying the atmosphere is out of the question, astronomers have figured out how to work with it. To distort the mirror of the telescope itself though the magic of adaptive optics. Mon, 19 May 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-88-the-hubble-space-telescope/ Our understanding of the cosmos has been revolutionized by the Hubble Space Telescope. The breathtaking familiar photos, like the Pillars of Creation, pale in comparison to the astounding amount of science data returned to Earth. Hubble's getting old, though, serviced several times already, and due for another mission later this year. Let's relive the historic observatory's amazing life so far, and see what the future holds. Mon, 12 May 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/cosmology/ep-87-the-end-of-the-universe-part-2-the-end-of-everything/ Hopefully you've all recovered from part 1 of this set, where we make you sad about the future of the humanity, the Earth, the Sun and the Solar System. But hang on, we're really going to bring you down. Today we'll look far far forward into the distant future of the Universe, at timescales that we can barely comprehend. Mon, 5 May 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/cosmology/ep-86-the-end-of-the-universe-part-1-the-end-of-the-solar-system/ This is a show we wanted to do since we started Astronomy Cast but we always thought it was too early. We wanted you to know that we're positive, happy people with enthusiasm for astronomy and the future. It's time for some sadness. It's time for a grim look to see what the future holds for the Universe. This week we stay close to home and consider the end of humanity, the Earth, the Sun, and the entire Solar System. Next week we'll extend out to the very end of the Universe. Mon, 28 Apr 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/observing-astronomy/ep-85-detectors/ Our senses can only detect a fraction of the phenomena happening in the Universe. That's why scientists and engineers develop detectors, to let us see radiation and particles that we could never detect with our eyes and ears. This week we'll go through them all, so you can understand how we see what we can't see. Mon, 21 Apr 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/planets/our-solar-system/ep-84-getting-around-the-solar-system/ Have you ever wondered what it takes to get a spacecraft off the Earth and into space. And how managers at NASA can actually navigate a spacecraft to another planet? And how does a gravity assist work? And how do they get them into orbit? And how do they land? So many questions… Mon, 14 Apr 2008 00:00:00 GMT http://www.astronomycast.com/physics/ep-83-wave-particle-duality/ Have you ever heard that photons behave like both a particle and a wave and wondered what that meant? It's true. Sometimes light acts like a wave, and other times it behaves like a little particle. It's both. This week we discuss the experiments that demonstrate this, explain how scientists figured it all out in the first place. What does wave/particle duality have to do with astronomy? Well, everything, since light is the only way astronomers can see out into the Universe. Mon, 7 Apr 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/planets/our-solar-system/ep-82-space-junk/ We're polluting every corner of our own planet, so it only makes sense that we'll take our trashy habits out into space with us. This week we look at the myriad of ways we're messing up space, from the trash orbiting the planet to the radiation we're leaking out into space. Mon, 31 Mar 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-81-questions-on-the-shape-size-and-centre-of-the-universe/ As predicted we got a lot of questions from people about our trilogy of shows on the size, shape and centre of the universe. Today we'll do our best to clear them all up.As always, if you're still confused drop us an email to info at astronomycast dot com. Mon, 24 Mar 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-80-craters/ Pamela's attending the 39th Lunar and Planetary Sciences Conference, and you know what that means: the Moon… and planets! When you think of the Moon, you think of craters. In fact, that's a big theme this week at the conference, so Pamela took it as inspiration. Here you go, the week we drove the show into a crater. Wait… there's got to be a better way to describe this. Mon, 17 Mar 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-79-how-big-is-the-universe/ We’re ready to complete our trilogy of discovery about the universe. We’ve learned that it has no center; rather everywhere is its center and nowhere. We discovered that the universe seems to be flat. It not open, it is not closed, it is flat. If that doesn’t make any sense, you need to listen to the previous show because there’s no way I could give that an explanation. So now we want to know: “How big is it?” Does it go on forever or is it finite in scale? How much of it can we see? Mon, 10 Mar 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-78-what-is-the-shape-of-the-universe/ Some of the biggest questions in the universe depend on its shape. Is it curved? Is it flat? Is it open? Those may not make that much sense to you, but in fact it’s very important for astronomers. So which is it? How do we know? How did we figure it out? Why does it matter? Mon, 03 Mar 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-77-where-is-the-centre-of-the-universe/ There are some people – I’m not naming names – who think the universe revolves around them. In fact, for most of humankind, everybody thought that. It’s only been in the last few hundred years that scientists finally puzzled out that the Earth isn’t the centre of the universe at all. That begs the question: where is the centre? Mon, 25 Feb 2008 00:00:00 GMT http://www.astronomycast.com/physics/ep-76-lagrange-points/ Gravity is always pulling you down, but there are places in the solar system where gravity balances out. These are called Lagrange points and space agencies use them as stable places to put spacecraft. Nature is on to them and has already been using them for billions of years. Mon, 18 Feb 2008 00:00:00 GMT http://www.astronomycast.com/listeners/student-questions/student-questions-curtis-high-school/ This is our second installment in our series of student questions shows and these questions come to us from Curtis High School. Sat, 16 Feb 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-75-stellar-populations/ After the big bang, all we had was hydrogen, a little bit of helium, and a few other trace elements. Today, we’ve a whole periodic table of elements to enjoy, from oxygen we breathe to the aluminium cans we drink from to the uranium that powers some people’s homes. How did we get from plain old hydrogen to our current diversity? It came from stars, in fact successive generations of stars. Mon, 11 Feb 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-74-antimatter/ Sometimes, we don’t get to decide what our show’s about. So many threads come together at the same time driving the decision for us. This is one of those situations. We’ve gotten so many questions from listeners in just the last week about antimatter that our show had just been chosen for it. You command, we obey. Let’s talk about antimatter. Mon, 04 Feb 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-73-questions-show-8/ We’ve been so crazy following our own whims through the universe that we’ve neglected your questions. That ends today. It’s time to dig deep into our overflowing email box to retrieve the puzzling questions our listeners have sent in. Mon, 28 Jan 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-72-cosmic-rays/ We’re going to return back to a long series of episodes we like to call: Radiation that Will Turn You Into a Superhero. This time we’re going to look at cosmic rays, which everyone knows made the Fantastic Four. These high-energy particles are streaming from the Sun and even intergalactic space, and do a wonderful job of destroying our DNA, giving us radiation sickness, and maybe (hopefully!) turning us into superheroes. Mon, 21 Jan 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-71-gravitational-waves/ When he put together his theories of relativity, Einstein made a series of predictions. Some were confirmed just a few years later, but scientists are still working to confirm others. And one of the most fascinating is the concept of gravitational waves. As massive objects move in space, they send out ripples across the Universe that actually distort the shape of matter. Experiments are in place and in the works to detect these gravitational waves as they sweep past the Earth. Mon, 14 Jan 2008 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-70-how-to-win-a-nobel-prize/ Just a couple of shows ago, we showed you how to get a career in astronomy. Now that you've got your career in astronomy, obviously the next goal is to win a Nobel prize. We're here at the American Astronomical Society meeting in Austin, which is just one tiny step that a person has to take before you get that Nobel prize. Before you get that call in the middle of the night from Sweden, you're going to need to come with an idea, do some experiments, write a paper, get published and a bunch of other stuff. This week, we'll tell you all about it. Mon, 07 Jan 2008 00:00:00 GMT http://www.astronomycast.com/listeners/student-questions/student-questions-farmersburg/ Thanks to GLAST, Astronomy Cast is now able to provide equipment to send to high school teachers who want to Pamela and Fraser to do a special questions show just for their class. We will be making this shows available on the feed on days other than Monday (that's still reserved for your regularly scheduled Astronomy Cast). This is the first one available and comes with questions from Farmersburg School. Sun, 06 Jan 2008 00:00:00 GMT http://www.astronomycast.com/physics/ep-69-the-large-hadron-collider-and-the-search-for-the-higgs-boson/ When it was first developed, the standard model predicted a collection of particles, and thanks to more and more powerful colliders, physicsists have been able to find them all except one: the Higgs-Boson. It's an important one because it should explain how objects have mass. The European Large Hadron Collider should have the power and sensitivity to find the Higgs-Boson. Mon, 31 Dec 2007 00:00:00 GMT http://www.astronomycast.com/astronomy/ep-68-globular-clusters/ This week we're going to study some of the most ancient objects in the entire Universe; globular clusters. These relics of the early Universe contain hundreds of thousands of stars, held together by their mutual gravity. Since they formed together, they give astronomers a unique way to test various theories of stellar evolution. Mon, 24 Dec 2007 00:00:00 GMT http://www.astronomycast.com/uncategorized/episode-67-building-a-career-in-astronomy/ With all the enthusiasm that’s being generated with astronomy, it’s had a bit of a strange side-effect. We’ve been causing some of our listeners to have midlife crises about their careers. We’ve had other people who just want advice – they’re moving into college for the first time and they want to direct the courses they’re going to be taking into astronomy. Some other people already have skills that are very useful and have wondered how they can help up or even change their career to be working in the field. We thought we’d try and answer everyone’s questions all at once and just run through the major career paths you can take that relate to astronomy and space, and the kinds of things you’ll need to do to actually make yourself a good candidate for that field. Mon, 17 Dec 2007 00:00:00 GMT http://www.astronomycast.com/observing/episode-66-how-amateurs-can-contribute-to-astronomy/ Astronomy is one of the few sciences where amateurs make meaningful contributions to discoveries. Many professional researchers work hand-in-hand with teams of amateurs to make discoveries that just wouldn't be possible without this kind of collaboration. In fact, Pamela regularly relies on dedicated enthusiasts for her data on variable stars. Mon, 10 Dec 2007 00:00:00 GMT http://www.astronomycast.com/solar-system/episode-65-the-end-of-our-tour-through-the-solar-system/ All good things come to an end - we now find ourselves in the outer reaches of the solar system where our Sun is hard to distinguish from the other bright stars in the sky. But we're not done with the solar system, there's some stuff that's leftover. This week, we look at the outer reaches of the solar system and how it interacts with the rest of the universe. Mon, 03 Dec 2007 00:00:00 GMT http://www.astronomycast.com/solar-system/episode-64-pluto-and-the-icy-outer-solar-system/ It's been a long journey, 64 episodes, but now we're back where we began: Pluto. Last time we talked about how Pluto lost its planethood status, so we won't go over all that again. This time we're going to talk about Pluto, its moons, the Kuiper belt, and the other icy objects that inhabit the outer Solar System. Mon, 26 Nov 2007 00:00:00 GMT http://www.astronomycast.com/solar-system/episode-63-neptune/ We’ve reached Neptune, the final planet in our tour through the solar system – but don’t worry! The tour’s not over, but after this week we’ll be all out of planets. Neptune has a controversial story about its discovery, some of the strongest winds in the solar system and some weird moons. Mon, 19 Nov 2007 00:00:00 GMT http://www.astronomycast.com/solar-system/episode-62-uranus/ This week, we're on to the next planet in the solar system. We don't know a whole lot about this blue gas planet, but today we'll cover some of the neat stuff we do know, including it's faint rings, sideways axis of rotation and its rocky core - a first in the gas planets we've encountered so far in our tour. Mon, 12 Nov 2007 00:00:00 GMT http://www.astronomycast.com/solar-system/episode-61-saturns-moons/ We know that delaying this show one more week would be too dangerous, so here you go: Saturn's moons. These are some of the most interesting objects in the Solar System, from the spongy Hyperion, to the geysers on Enceladus, to the rainy, misty, oceany Titan. They've kept Cassini busy for years, and scientists will likely be pondering them for decades. Mon, 05 Nov 2007 00:00:00 GMT http://www.astronomycast.com/cosmology/episode-60-questions-on-inflation/ It's about time for a question show again, so we'll have one last interruption to our planetary tour, to deal with the questions that arose from our inflation show.So if you still don’t understand inflation, take a listen to this week's show and as always, send us your questions. Mon, 29 Oct 2007 00:00:00 GMT http://www.astronomycast.com/solar-astronomy/episode-59-saturn/ Returning to our journey through the solar system, let's voyage away from the largest planet to the second largest, Saturn. Once again, we'll break up our visit because there's lots to talk about. This week, we talk about Saturn and its famous rings. Next week, we'll discuss its many moons. Mon, 22 Oct 2007 00:00:00 GMT http://www.astronomycast.com/cosmology/episode-58-inflation/ We interrupt this tour through the solar system to bring you a special show to deal with one of our most complicated subjects: the big bang. Specifically, how it's possible that the universe could have expanded faster than the speed of light. The theory is called the inflationary theory, and the evidence is mounting to support it. Einstein said that nothing can move faster than the speed of light, and yet astronomers think the universe expanded from a microscopic spec to become larger than the solar system, in a fraction of a second. Mon, 15 Oct 2007 00:00:00 GMT http://www.astronomycast.com/solar-system/episode-57-jupiters-moons/ Last week we talked about Jupiter and we could sense right away it would be too much to handle. This week, we'll talk about Jupiter's moons - how many are there? What makes them so interesting? Is it true that the most likely place in the solar system to find life (other than Earth) is actually on one of Jupiter's moons? Hang on tight. We're going to cover a lot. Mon, 08 Oct 2007 00:00:00 GMT http://www.astronomycast.com/solar-system/episode-56-jupiter/ Last week we talked about rubble, this week we're going to dig into the largest planet in the Solar System: Jupiter, but will it all just be hot gas? There's so much to talk about, we've decided to break this up into two shows. This week we're going to just talk about Jupiter, and then next week, we're going to cover its moons. Mon, 01 Oct 2007 00:00:00 GMT http://www.astronomycast.com/solar-system/episode-55-the-asteroid-belt/ In the last few weeks we've had many emails saying that our tour of the solar system would not be complete without a show on the asteroid belt. Your wish is our command! We talked about Mars in episode 52, and now that we're back on track our next stop is the asteroid belt. Mon, 24 Sep 2007 00:00:00 GMT http://www.astronomycast.com/stars/episode-54-questions-show-6/ It's been a while, so let's catch up with the listener questions. We've got some easy ones, some hard ones and probably some impossible ones. We talk about our universe as a black hole, tidal locking of planets like Uranus, colours of stars at different ages, our universe's birthday and more. Mon, 17 Sep 2007 00:00:00 GMT http://www.astronomycast.com/interviews/episode-53-astronomy-in-science-fiction/ This is a very different episode of Astronomy Cast. As we mentioned last week, Pamela recently attended the Dragon*Con science fiction convention in Atlanta, Georgia. While she was there, she participated in a special live edition of Astronomy Cast with special guest Dr. Kevin Frazier. Kevin is a NASA scientist, and the science consultant for the TV shows Battlestar Galactica and Eureka. He and Pamela work through physics and astronomy in popular science fiction. What they get right, and what they get wrong... so very wrong. Mon, 10 Sep 2007 00:00:00 GMT http://www.astronomycast.com/astrobiology/special-episode-panspermia/ As a reward to the all the dedicated fans who completed our demographic survey, we released this special episode of Astronomy Cast. As promised, we're now releasing this episode to all of our subscribers. Panspermia is a controversial theory that life on Earth originated… out there. Maybe it started out in a cosmic dust cloud or originated from another planet, but somehow the very first lifeforms made the trip through the vacuum of space and colonized our home planet. Tue, 04 Sep 2007 00:00:00 GMT http://www.astronomycast.com/solar-system/episode-52-mars/ Today we consider Mars, the next planet in our journey through the Solar System. Apart from the Earth, it's the most explored planet in our Solar System. Even now there are rovers crawling the surface, orbiters overhead, and a lander on its way. It's a cold, dry desert, so why does this planet hold such fascination? Mon, 03 Sep 2007 00:00:00 GMT http://www.astronomycast.com/solar-system/episode-51-earth/ So, another week, another planet. Last week we discussed Venus, and that means this week it is time for our home planet - Earth. Mon, 27 Aug 2007 00:00:00 GMT http://www.astronomycast.com/solar-system/episode-50-venus/ Last week we talked about Mercury, so this week our planetary parade proceeds to Venus. It's the brightest object in the sky, the hottest object in the solar system, and it's probably one of the most deadly places to go and visit. Mon, 20 Aug 2007 00:00:00 GMT http://www.astronomycast.com/solar-system/episode-49-mercury/ We're still digging through the thousands of comments and suggestions from the listener survey but we hear your requests and suggestions, and now you get to start reaping the benefits. Today we start our survey of the solar system with Mercury. What mysteries is it hiding from us? How similar is Mercury to the other rocky planets? How much do we really know about this first rock from the Sun? Mon, 13 Aug 2007 00:00:00 GMT http://www.astronomycast.com/stars/episode-48-tidal-forces-across-the-universe/ Last week we talked about tidal forces within our solar system. This week we're going to expand our view and encompass the entire universe. Some of the most dramatic events originate from tidal forces caused by gravity: other worlds, galaxies, black holes and even entire clusters of galaxies are under this influence. Mon, 06 Aug 2007 00:00:00 GMT http://www.astronomycast.com/solar-system/episode-47-tidal-forces/ Consider the following: we've got tides here on Earth, the Moon only shows one face to the Earth, we've got volcanoes on Io, and ice geysers on Enceladus. All these phenomena originate from a common cause: the force of gravity stretching across space to tug at another world. Mon, 30 Jul 2007 00:00:00 GMT http://www.astronomycast.com/star-formation/episode-46-stellar-nurseries/ We've discussed star formation in the past, but now we wanted to talk about the different kinds of stellar nurseries we see across the Universe. We know where our Sun came from because we can look out and see different stellar neighborhoods at every stage of development. It takes a village of gas and dust to raise a star. Mon, 23 Jul 2007 00:00:00 GMT http://www.astronomycast.com/cosmology/episode-45-the-important-numbers-in-the-universe/ This week we wanted to give you a basic physics lesson. This isn't easy physics, this is a lesson on the basic numbers of the Universe. Each of these numbers define a key aspect of our Universe. If they had different values, the Universe would be a changed place, and life here on Earth would never have arisen. Mon, 16 Jul 2007 00:00:00 GMT http://www.astronomycast.com/cosmology/episode-44-einsteins-theory-of-general-relativity/ If you remember way back to Episode 9, we covered Einstein's Theory of Special Relativity. Well, that's only half of the relativity picture. The great scientist made an even more profound impact on physics with his theory of general relativity, replacing Newton with a better model for gravity. Mon, 9 Jul 2007 00:00:00 GMT http://www.astronomycast.com/questions/episode-43-questions-questions-5/ It's time to answer the questions again. And this time we've got some doozies. Is the Universe rotating? Is space something, or is it nothing? Is dark energy evenly distributed? What would happen if an astronaut went out the airlock, without a spacesuit. Want to know the answers? Well, you've got to listen. Mon, 2 Jul 2007 00:00:00 GMT http://www.astronomycast.com/physics/episode-42-magnetism-everywhere/ You probably don't realise it, but magnetic fields are everywhere. We're not talking about the magnets in your speakers, your electronic equipment or on the fridge door. We're talking about the gigantic magnetic fields that surround planets, stars, galaxies and some of the most exotic objects in the Universe. Mon, 25 Jun 2007 00:00:00 GMT http://www.astronomycast.com/observatories/episode-41-the-rise-of-the-supertelescopes/ The last decade has been the golden age of astronomy, with new observatories and space telescopes pushing out our understanding of the Universe. We can see billions of light years away, watch dynamic events unfold in almost real-time, and see into every corner of the electromagnetic spectrum. Just you wait: things will only get better. Here come the supertelescopes! Mon, 18 Jun 2007 00:00:00 GMT http://www.astronomycast.com/meetings/episode-40-american-astronomical-society-meeting-may-2007/ Once again, Pamela does her duty as an astronomer and joins her colleagues at the American Astronomical Society's meeting, held in May, 2007 on Honolulu, Hawaii. With all that sand, surf and sun, how did anyone get any science done? Pamela tracked down the interesting stories, and brought them back so we could analyze them. Mon, 11 Jun 2007 00:00:00 GMT http://www.astronomycast.com/skepticism/episode-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 UFOs, and why they're not real science. Mon, 4 Jun 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070528.mp3 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 dozen kilometres across. Mon, 28 May 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070521.mp3 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 to the edges of the observable Universe. Mon, 21 May 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070514.mp3 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 these energetic explosions. Mon, 14 May 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070507.mp3 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 these questions, you'll want to listen to this week's show. Mon, 7 May 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070430.mp3 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 Earth. Mon, 30 Apr 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070423.mp3 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 make sure your first investment in this wonderful hobby is money well-spent. Mon, 23 Apr 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070416.mp3 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 this elusive particle was first theorized and finally discovered. Mon, 16 Apr 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070409.mp3 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 impossible) to test in the real Universe. Mon, 9 Apr 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070403.mp3 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. Put in your headphones, head outside and enjoy the sunshine while you listen to this week's podcast. Mon, 2 Apr 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070326.mp3 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 stop them? Mon, 26 Mar 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070319.mp3 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 it, so your unsatisfaction doesn't haunt you any more. Mon, 19 Mar 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070312.mp3 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? Mon, 12 Mar 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070305.mp3 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. Mon, 5 Mar 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070225.mp3 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? Mon, 26 Feb 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070219.mp3 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 picked up signals from alien television stations? Where's all the life? Mon, 19 Feb 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070212.mp3 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 details and we'll be set. Mon, 12 Feb 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070205.mp3 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 variable stars, and they demonstrate just how bizarre and dangerous the Universe can be. Mon, 5 Feb 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070129.mp3 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 hole? And just how large would a rock have to be before its gravity is so strong that a human can't escape? Mon, 29 Jan 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070121.mp3 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 closest, brightest supernova in recent memory. Mon, 22 Jan 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070115.mp3 The sudden brightening of Comet McNaught has reminded us what a treat it can be to see a comet with the unaided eye. A diffuse ball with a long tail stretching across the sky. There's nothing else in the night sky that can compare to a bright comet. But what are these objects, where do they come from, and what can they tell us about the formation of the Solar System? Mon, 15 Jan 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070107.mp3 We're finally ready to deal with the topic you've all been waiting for: Schwarzschild swirlers, Chandrasekhar crushers, ol' matter manglers, sucking singularities - you might know them as black holes. Join as as we examine how black holes form, what they consume, and just how massive they can get. Mon, 8 Jan 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-070101.mp3 We take the Moon for granted, but its effect on the Earth is very important; possibly even critical for the formation of life. But where did it come from? Did the Earth and Moon form together? Or did the Earth capture a wayward Moon? Or was there a more catastrophic cause to this lunar mystery? Mon, 1 Jan 2007 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-061225.mp3 We see the Universe in visible light with our photon detecting eyes. We can feel infrared heat with our photon detecting hands, and we get sunburns with our ultraviolet photon detecting skin (ouch). But there's a whole spectrum of photons out there, from radio waves to gamma rays that astronomers use to understand the Universe. It's time to see the whole picture. Mon, 25 Dec 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-061218.mp3 We finally get organized enough deal with several listener questions: isn't dark matter just regular stuff we can't see? how can parts of the Universe be expanding faster than the speed of light? what will Betelgeuse look like when it explodes as a supernova? what's the speed of gravity? All these and more questions are answered. Mon, 18 Dec 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-061211.mp3 No more suspense. This week we blow the biggest stars up. Kaboom. Want more details? Then you've got to listen. Mon, 11 Dec 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-061204.mp3 We've celebrated the birth of new stars, but the stellar lifecycle doesn't end there. Stars like our Sun will spend billions of years fusing together hydrogen and pumping out energy. And when the fuel runs out, their death is as interesting as their birth. This week Fraser and Pamela trace out this stellar evolution, and explain what the future holds for stars, large and small. Mon, 4 Dec 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-061127.mp3 Most parents have had that uncomfortable conversation with their children at some point. Mommy, Daddy, where do stars come from? You hem and haw, mumble a few words about angular momentum and primordial hydrogen and then cleverly change the subject. Well, you don't have to avoid the subject any longer. Pamela and Fraser describe formation of stars, large and small, in a tasteful manner, using only understandable and scientific language. Mon, 27 Nov 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-061120.mp3 The discovery of dark energy was one of the biggest surprises in astronomy. Instead of a nice, predictable expanding Universe, acted on only by gravity, astronomers turned up a mysterious repulsive force accelerating the expansion of the Universe. Fraser and Pamela explain the evidence for a dark energy, and a few possible theories for what could be providing this repulsive force Mon, 20 Nov 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-061113.mp3 You hear distances all the time in astronomy. This star is 10 light-years away; that galaxy is 50 million light-years away; that Big Bang over there happened 13.7 billion years ago. But how did astronomers actually figure out how far away everything is? It's not a single measuring stick. Instead, astronomers have built up a series of overlapping measuring tools (yes, we're calling supernovae and variable stars tools), which take us from right around the corner to very ends of the Universe. Get out your ruler... no, the bigger one... never mind... just listen. Mon, 13 Nov 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-061106.mp3 It's all relative. How many times have you heard that? Well, when you're traveling close to the speed of light, everything really is relative; especially the passage of time. This week, Fraser and Pamela give you the skinny on Einstein's Special Theory of Relativity. After listening to a few thought experiments, you too should be able to wrap your head around this amazing theory. Mon, 6 Nov 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-061030.mp3 Dress warmly, gather some friends and family, and head outside to watch sand burn in the upper atmosphere. There's nothing like a good meteor shower. Fraser and Pamela explain this beautiful phenomenon: what causes them, the best storms and showers to watch for, and different types of meteors you might see. Mon, 30 Oct 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-061023.mp3 Got your eye on that $40 telescope at Walmart? Wait, hear us out first! Fraser and Pamela discuss strategies for getting into amateur astronomy - one of the most worthwhile hobbies out there. We discuss what gear to get, where to look, and how to meet up with other astronomy enthusiasts. Mon, 23 Oct 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-061016.mp3 Last week's episode started out with a bang- a Big Bang. This week we continue our discussion into the beginning of everything. We present three additional lines of evidence that have led astronomers to the conclusion that our Universe started out as a singularity 13.7 billion years ago, and has been expanding ever since. Mon, 16 Oct 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-061009.mp3 As a tribute to John Mather and George Smoot, the two leaders of the Cosmic Microwave Background Explorer (COBE) satellite science team, and winners of this year's Nobel Prize for Physics, we head back to the beginning of everything- the Big Bang. Follow as we trace the Big Bang's discovery, and one of the most important lines of evidence: the cosmic microwave background radiation which was predicted by theory and then discovered by accident. Mon, 9 Oct 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-061002.mp3 Dark matter . . . What is it? Nobody knows for sure, but it's definitely there. Or maybe it's not there, and we just need some redefinition of gravity at vast scales. Join Fraser and Pamela as we discuss the discovery, detection, and possible explanations of dark matter. Mon, 2 Oct 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-060922.mp3 You have lived on the Earth all your life, so you'd think you know plenty about planets. As usual though, the Universe is stranger than we assume, and the planets orbiting other stars defy our expectations. Gigantic super-Jupiters whirling around their parent stars every couple of days; fluffy planets with the density of cork; and Earth-sized fragments of exploded stars circling pulsars. Join us as we round up the latest batch of bizarro worlds. Mon, 25 Sep 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-060919.mp3 Look down at your feet. There... you're looking at a planet. Now look into the night sky and you should be able to spot a few more. After that, spotting additional planets becomes really hard, especially when you're trying to find them orbiting other stars. This week we discuss the techniques astronomers use to locate distant worlds. Mon, 18 Sep 2006 00:00:00 GMT http://media.libsyn.com/media/astronomycast/AstroCast-060911.mp3 Pluto. It's a planet, then it's not. This week we review Pluto's history, from discovery to demotion by the International Astronomical Union. Learn the 3 characteristics that make up a planet, and why Pluto now fails to make the grade. Mon, 11 Sep 2006 00:00:00 GMT