[+] Pluto. It's a planet, then it's not. This week we ...

[-] 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. http://cdn1.libsyn.com/astronomycast/AstroCast-060911.mp3 originally aired: September 10th, 2006 note: Since the recording of this show, dwarf planet 2003 UB313 has been officially named Eris, and its moon is Dysnomia

[+] Dark Matter is invisible, but astronomers can tease out the ...

[-] Dark Matter is invisible, but astronomers can tease out the shape it has by looking at the orbits of dwarf galaxies around the Milky Way.

[+] A very interesting discussion about the possible existence of UFOs ...

[-] A very interesting discussion about the possible existence of UFOs (Unidentified Flying Objects) and life on other planets.

[+] Two U.S. robotic rovers are entering their fourth year exploring ...

[-] Two U.S. robotic rovers are entering their fourth year exploring opposite sides of Mars, an unexpected length of time for a mission planned for only three months. Yet, now after three years, the mechanical geologists keep plodding along, studying Martian rocks and soil. Although they show certain signs of aging, new computer software has given them expanded capabilities, proving you can teach an old robot new tricks

[+] The U.S. space agency NASA has stepped up its search ...

[-] The U.S. space agency NASA has stepped up its search for the original videotapes of the first moon landing in 1969. The tapes are missing, but NASA does not consider them lost. They are of higher visual quality than the images the world saw 37 years ago.

[+] The Canadian Shield is marked by some of the largest ...

[-] The Canadian Shield is marked by some of the largest and best preserved meteorites in the world. Learn about these space rocks which fall into Canada everyday.

[+] Look down at your feet. There… you're looking at a ...

[-] 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. Originally broadcast: Sept 16, 2006

[+] Astronomers found the 2nd smallest exoplanet yet, weighing in at ...

[-] Astronomers found the 2nd smallest exoplanet yet, weighing in at about 4 Earth masses. Author: Nancy Atkinson Source: http://www.universetoday.com/2010/01/07/second-smallest-exoplanet-found/