SJAA Ephemeris January 2013 | SJAA Home | Contents | Previous | Next

The Last Month in Astronomy


DEC-19-2012 • Tau Ceti Maybe • Steve Vogt of UCSC is the co-author of a study showing evidence of 5 planets orbiting Tau Ceti. This is of interest for a few reasons. First, it might include a habitable planet. That planet is the 4th planet from the star with an orbital period of 168 days. It is more than 4 times more massive than the Earth and probably not a rocky planet but it might be in the “Goldilocks” zone. Second, Tau Ceti is less than 12 light years away, a neighbor really. Third, Tau Ceti is often mentioned in science fiction stories because of its proximity and also because it is a sun-like star. To be sure, these are planetary candidates, not yet confirmed. Given the proximity, why haven’t planets been detected here before. One reason is that the multiple planets make it difficult to separate the signal from the noise. The discovery was made by reanalyzing 6000 observation of Tau Ceti made by 3 different instruments: HARPS (High Accuracy Radial velocity Planet Searcher) in Chile, UCLES (University College London Echelle Spectrograph) in Australia and HIRES (High Resolution Echelle Spectrometer) attached to Keck telescope in Hawaii.

DEC-14-2012 • Totally Toutatis • The 3 mile-long asteroid Toutatis came within 4.3 million miles of Earth on December 12. This is the closest this asteroid will come to Earth until 2069 and it is clear it won’t hit the Earth during the next 400 years, about as far as such predictions can be made accurately.

DEC-03-2012 • Voyager hits new region • The Voyager 1 spacecraft is leaving the solar system. It currently is in a region that has been previously unknown. This new region is sometimes called a magnetic highway. Edward Stone (Caltech) says “Although Voyager 1 still is inside the sun’s environment, we now can taste what it’s like on the outside because the particles are zipping in and out on this magnetic highway. We believe this is the last leg of our journey to interstellar space.”

NOV-28-2012 • Titanic weather change • The weather on Titan is changing. Air near the south pole is sinking whereas it was upwelling earlier in the Cassini mission. The difference is probably season-related. Studies of weather is somewhat restricted in the solar system because only 4 bodies have a solid surface and a substantial atmosphere: Earth, Mars, Venus and Titan.


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