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The Last Month in Astronomy


OCT-12-2012 • Dragon Unloaded • Commander Suni Williams and Flight Engineer Aki Hoshide used the ISS’s robotic arm to grab and connect the Dragon spacecraft. This craft took up 882 pounds of supplies and will return with more than twice the amount of stuff to be returned to Earth. Splashdown is scheduled for October 28. Dragon is the supply ferry launched by the private firm Space X.

OCT-10-2012 • Dry Ice at Venus • Venus is the hottest planet in the solar system, even hotter than Mercury. But scientists have found that the temperature high in the Venusian atmosphere can be quite cold. In fact, it can be cold enough for carbon dioxide to freeze out as snow. It would be about 125 km high.

OCT-09-2012 • X-ray Nova • The Swift space-based X-ray telescope has discovered a very rare X-ray nova near the center of the Milky Way. This is probably a dark hole with a stellar mass. The object now named Swift J1745-26 hit a peak in hard (higher energy) X-rays on September 18 but continued to brighten after that in soft X-rays. The object had been detected in other wavelengths but the atmosphere blocks X-rays. Boris Sbarufatti from Milan said “Once the X-rays fade away, we hope to measure its mass and confirm its black hole status.

OCT-04-2012 • Deep Impact: Act 3 • The NASA spacecraft Deep Impact studied comet Tempel 1 by using an impactor and running through the debris field. This was done on July 4, 2005. The craft was then redirected to comet Hartley 2 and it flew by that comet on November 4, 2010. Now it’s engines have been fired up again. This time the potential target is the near-Earth asteroid 2002 GT. The rocket fired for 71 seconds and it changed the speed of the craft by 4.5 mph.

OCT-03-2012 • New accuracy for Hubble • The Hubble constant, the speed at which the universe is expanding, has been measured to a new level of accuracy thanks to measurements by the Spitzer telescope. 10 Cepheid variable stars in the Milky Way and 80 more in the Large Magellanic Cloud were studied. By using the Spitzer’s Infrared capabilities these Cepheids could be studied without having to worry about dust. This helped to improve the accuracy of distance measurements that use this “standard candle”. Lead author of this study is Wendy Freedman of the Observatories of the Carnegie Institution for Science in Pasadena. She said “Just over a decade ago, using the words ‘precision’ and ‘cosmology’ in the same sentence was not possible, and the size and age of the universe was not known to better than a factor of two. Now we are talking about accuracies of a few percent. It is quite extraordinary.

SEP-24-2012 • Milky Way Halo • The Milky Way galaxy has a halo of hot (100,000 to 1,000,000 Kelvins) gas that has a mass that might be equal to the mass of the Milky Way galaxy itself. No, this doesn’t say anything about dark matter but it might be a solution to the missing baryonic matter question. (See question #3 in the August 2012 issue of the Ephemeris under “Astro Questions”).

SEP-06-2012 • ARP 116 • Astronomer Halton Arp created a catalog of galaxies called the “Atlas of Peculiar Galaxies”. Hubble has recently released an image of Arp 116, actually a pair of galaxies. One galaxy, also known as M60, is a large elliptical galaxy. It has a “companion”, the spiral galaxy 4647. The two galaxies look like they might be touching but so far they don’t appear to be pulling on each other. Instead, the two galaxies present a textbook example of the difference between ellipticals and spirals. The spiral contains many more new stars and therefore looks quite a bit more blue than the elliptical which is not creating a lot of new stars at this time.


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