(10s audio sample) A: Do know that sound? B: Sounds like my stomach after an entire domino's pizza. A: It came from Saturn, hang on and we'll explain. Welcome to show #-2 of slacker astronomy. a podcast about astronomy and just about anything else that floats over our heads. B: Every week or so we will bring you a summary of a recent news event from the world of astronomy. And during slow news weeks, we'll dance a jig. Those of you with iPod photos, be ready. A: This week we are going to talk about the northern lights, also known as the aurora borealis. We have Gassendi to thank for coining the term aurora borealis in 1621 after the roman goddess of the dawn of the same name, which means to shine at dawn. B: Scientists prefer to use that term over northern lights because they have a gene that requires them to make simple things complicated. Lawyers and literature professors also suffer from the same malady. A: In the southern hemisphere they are referred to, surprisingly enough, the southern lights or scientifically as the australias borealis because apparently South Africa, New Zealand and Argentina aren't allowed to see the southern lights. B: Aurorae are caused by high energy protons and electrons entering the earth's magnetic field. They are pulled down to the poles of the earth at high speed where they collide with atoms of oxygen and nitrogen gas in the upper atmosphere. This shakes up the electrons in the atoms and releases photons we see as light. When this happens at high intensity and at night parts of the sky will glow in eerie red and green colors. A: Slacker astronomy estimates that only 2% of the population of the Earth has ever seen an aurora. The reason is that they are only easily seen at very high latitudes in countries like Canada, Norway, Finland, Russia and southern New Zealand, Australia and Argentina. And for those regions you must live outside of a major city to see aurorae. The closer to the poles you are, the better the chance to see an aurora. For example, in northern Canada or Finland you may see an aurora half the nights of the year. But places like Texas and India may see it once a decade. B: The high energy protons that generate aurora originate in the Sun. The Sun emits a stream of these particles all the time. This stream ebbs and flows. When it is high, we get an aurora on Earth. Sometimes a massive explosion occurs on the Sun called a coronal mass ejection. A: Sounds like a college beer drinking technique to me. B: The explosion shoots out a ton of these particles into space. If they are aimed just right they will hit the Earth approximately 2-3 days later. An aurora storm then occurs and may last from minutes to as long as half a day. A: In 1989 such a storm was so powerful that it built up a charge on the electric grid in Quebec. Eventually there was so much charge that it shorted out the entire grid system causing a blackout of large portions of northeast canada and the United States. B: These coronal mass ejections have also been known to destroy satellites. In October of 2003 there was one so strong that had it been aimed at the Earth it probably would have killed the astronauts on the International Space Station with radiation poisoning if they did not immediately evacuate the station in their emergency Soyuz landing craft. Luckily we get some warning of these events so they can leave should it happen again. A: So why is all this news now? Aurorae are actually pretty complicated phenomenon because they involve the magnetic field. There is a joke in astronomy that if you want to stump an expert on any subject just ask "Yeah, so what about the magnetic field?" Yes, this is why astronomers aren't on Leno anymore. B: One of upsides of it being complicated is that aurora can tell you alot about the atmosphere and even the planet itself. So one way to study other planets is too study their aurorae. This is a relatively new area in astronomy as the first aurora outside of the Earth wasn't discovered until the mid 80's when the Voyager probe saw an aurora on Jupiter. A: In the February 17 issue of Nature a paper was published describing a newly discovered aurora on Saturn too. This was discovered using the Hubble Space Telescope and some quick thinking. Astronomers detected a one of those large coronal mass ejections from the sun in January of 2004. They were able to calculate the path the particles would take through space and noticed that some of them would eventually impact Saturn. B: So the Hubble Space Telescope began imaging Saturn around the time of predicted impact. The space probe Cassini, which is currently orbiting Saturn, was on its way at the time and turned its radio telescope on to listen for radio signals from Saturn. Here is what they heard: (10s radio sample) B: Sounds like a Phillip Glass piece. A: There is a sudden increase in the volume about halfway through the recording. That is the initial impact of the particles hitting Saturn's magnetic field. It is followed by a back and forth sound as more particles pour into Saturn. Let's hear it again: (replay) B: At the same time that the radio noise was being recorded the Hubble Space Telescope detected an aurora around Saturn's southern pole. Three beautiful images of the aurora were made and can be seen in the show notes at slackerastronomy.org. A: We mentioned earlier that Jupiter also has an aurora. But it is a little different than the one on Earth and Saturn. Jupiter's aurorae is caused by its moon Io which has volcanos that spew sulfur into space. This sulfur is grabbed by Jupiter's intense magnetic field and is electrified as it is pulled down to the planet's poles. There it impacts the atmosphere of Jupiter and creates light like the aurora on Earth. Since this aurora is fed by an ever present Moon and not by storms on the Sun, the Jupiter aurora is almost always present at both polls. B: If you live at a high latitude you may want to try and catch an aurora. Go to spaceweather.com or skyandtelescope.com to sign up for e-mail alerts and aurora predictions. If you haven't seen an aurora yet then you are missing out on one of natures most beautiful and majestic events. Aaron will surely regale us with his aurorae experiences later this month when we do our first chat roundup show. A: We'll have to shut him up! B: The key to shutting aaron up is to put a playstation control in his hand with galaga loaded. A: I'll remember that! B: This was episode number negative two of Slacker Astronomy. Visit slacker astronomy dot org for show notes including the pictures from HST, links to the audio and more. A:This was our fourth show during our experimental season before we officially launch the site in March. Please give us feedback at the site or by e-mailing info at slackerastronomy dot org. B: Also check out our welcome podcast available on our home page to learn more about us, what we plan to do with this podcast, why we're doing it, and a little matchmaking is thrown in too. A: I'm X and on behalf of X and Aaron thanks for listening and no, you dont get your 4 minutes back. B: Clear Skies and Clear Bandwidth. This has been Slacker Astronomy, a volunteer collaboration for you, for fun, for the voices in our heads.