December 12th show

Unfortunately, I wasn't unable to record this show (CD-R malfunction) so I can't post it. There was lots of research results released last week, but I just focused on news and new results concerning the Sun:

• News: Congrats to Alexander Sharpe, Joshua Leviton, and Alistair McGregor for winning the Cassini "Scientist for a Day" competition, Prof. Geoff Marcy of UC-Berkeley for being chosen to deliver the annual John N. Bahcall Public Lecture at the Smithosonian Air & Space Museum, and Prof. Hinz, Dr. Kuchner, and Dr. Serabyn for being awarded time on the Keck inteferometer to study the disks left behind around stars after they form; design for the optical telescope system on the upcoming James Webb Space Telescope passes its preliminary design review; NASA announces plan to use a series of high altitude balloons called BARREL to study Van Allen belts and a new mission to the Moon called GRAIL to measure its gravitational field.
• Sun: The 7 December 2007 edition of Science was devoted to initial results of the Hinode satellite (for more information on this mission, go here) which studies X-ray emission from the Sun. One very puzzling aspect of the Sun and other similar stars is that the outermost layers, called the chromosphere and the corona, are significantly hotter than the photosphere, which is the region of the Sun where most of the visible light we see originates. Before I discuss the new results on this region, I want to first briefly describe the current best picture of what goes on inside the Sun. The Sun is quite a complicated object, with an extremely hot and dense center where fusion takes places (for example, "hydrogen turning into helium" as quoted in the song which I being many shows). These fusion reactions releases energy in the form of light. However, the region of the Sun that is hot and dense enough to sustain fusion reactions is nowhere near the size of the entire Sun, and how this energy goes from the inner center to the outer regions is quite complicated. In the region of the Sun just around the Hydrogen burning core, this energy radiates outward. However, this radiative region does not reach the surface, and this radiative core is surrounded by a convective envelope - meaning that gas heated by the radiative core rises up, and as it rises it cools, causing it to fall and get heated again, just as happens on the Earth from solar heating and similar to steam from a boiling kettle. This process of hot gas rising/cool gas falling is actually a very efficient method of getting the energy from the hot interior to the outer regions of the Sun, and most of the optical light we see from the Sun is from the top level of this convective layer called the photosphere. (The name "photosphere" is just a contraction of photon sphere, ie. the sphere where the photons - light - we see come from). However, it was discovered that outside this photosphere, where a large fraction of the energy generated by the fusion reactions in the center of the Sun escapes in the form of sunlight and travels into space, are hotter layers called the chromosphere and corona which are responsible for the solar wind, solar fares, coronal mass ejections, etc. Why? Well, since most of the light produced in these regions of the Sun is emitted in the X-ray band, not optical, to figure this out one needs high-resolution and sensitive X-ray observations of these regions, which Hinode was designed to provide. Astronomers had long suspected that the magnetic field generated in the convective layers of the Sun (all the gas in the Sun is ionized, meaning that it is in the form of electrons and atomic nuclei - mostly protons, and moving ions can produce electric and magnetic fields) was responsible, specifically through magnetic field generates by different patches of moving gas in the Sun interacting through each other. This speculation was believed to by confirmed by Hinode observations which detected a lot of "X-ray jets", X-ray emission produced by fast moving material believed to be created when these magnetic fields overlap, many more than had been detected before, which occur often enough and produce enough energy to explain most of the solar wind and coronal mass ejections. This just one of the many exciting results this satellite announced, and I encourage all of you to check out the Science issue
  
• Calendar
• Interview: with Dr. Daniel Savin of the Columbia Astrophysics Laboratory (Columbia University) on the field of Laboratory Astrophysics.

As always, comments and questions are appreciated.