Hello, astro-nuts!

I hope you all had a great weekend; it was close to 70 degrees most of the time here in central PA, with lovely clear skies. It won't last, however. Rain is headed our way tomorrow, and the system might pick up some additional moisture from Tropical Storm Ida, depending on where the storm goes after landfall. Timing is everything; check out the Hurricane Center for more info. Anyway, today's news stories are all about far away galaxies!

Check This Out!

This past weekend was one of near misses, both for our planet and the International Space Station. A piece of space debris briefly posed a threat to the ISS on Friday, to the point where mission control may have had to order the crew to head for the Soyuz escape capsules. It looked at that point like the debris could pass within 6/10 of a mile and there wasn't time to move the station. As it turned out, the debris was to miss by a greater distance and there was no need for the crew to head to the capsules. Then, later that same day, 19-foot wide Asteroid 2009 VA came within about 8,700 miles of Earth's surface (inside the orbit of geosynchronous satellites) but did not enter our atmosphere. If it had, it would have disintegrated high above the ground and posed little threat to those on the ground. It was spotted about fifteen hours prior to its closest approach by the Catalina Sky Survey group.

Calling all college students! NASA is accepting applications through December 18th for undergraduate and graduate student experiments that will be carried by a NASA high-altitude research balloon which is launched from Columbia Scientific Balloon Facility in Fort Sumner, New Mexico. According to NASA, the goals of this project are "to provide a space test platform to encourage student research and stimulate the development of student satellite payloads and other space-engineering products". For that reason, these experiments may include compact satellites or prototypes. A question and answer teleconference will be held for anyone interested on November 13th at 11am EST. Check out all the details and find application materials at the project website. Good luck!

This week the Moon pairs up with a bunch of celestial beauties. Tuesday at dawn, Leo's star Regulus can be see about four degrees to the Moon's upper left. On Thursday morning, Saturn will be about eight degrees to the left of a thinning crescent Moon (what I like to call the "Cheshire Cat Moon"). Virgo's star Spica pairs up with an even thinner crescent Moon on the 14th; the pair will be about four degrees apart. Then of course the "really big shew" (to quote Ed Sullivan) will be next Tuesday morning as the Leonid Meteor Shower peaks. More on that later this week.

Astronews!

Unknown to us until recently, a grouping of galaxies resides nearly seven billion light-years away from Earth. It took two powerful ground-based telescopes to find it, and is the first of its kind to be found at such a distance. We know that stars form within galaxies, and galaxies tend to belong to clusters. Similarly, matter in space tends to form "clumps" that are part of what is called the "cosmic web". Galaxies tend to be embedded within wispy filaments that stretch millions of light years in length and essentially make up the "skeleton" of the Universe. Where these filaments intersect are where immense galaxy clusters reside. The VIMOS instrument of ESA's Very Large Telescope and FOCAS on the Subaru Telescope were used to observe a large filament structure surrounding the distant galaxy cluster. These instruments have measured the distances to over 150 galaxies and scientists were then able to create a 3-D view of this immense structure. Many of these groups contain members which are ten times bigger than our own Milky Way, some even bigger. The groups themselves could be at least ten thousand times the size of the Milky Way (estimated at about 100,000 light-years across).

Twenty-two galaxies have been recently surveyed; all were thought to have dated back to about 800 million years after the Big Bang. One in particular was dated at about 787 million years after the Big Bang because of its hydrogen signature. This is the first finding of a "dropout galaxy" from an era called the reionization epoch, which is currently the farthest back in time astronomers can observe. About 400,000 years after the Big Bang, electrons and protons were joining to form natural hydrogen, and prior to 1 billion years post Big Bang, this hydrogen started to form stars in the first galaxies. These stars radiated energy and changed the hydrogen back into its ionized form (hence "reionization epoch"). In order to find out when this period began, a search for "dropout" galaxies was started in which the "redness" of filters was increased such that increasing wavelengths would be revealed. Older galaxies would stop appearing ("drop out) when a certain redness was reached. The specific wavelength of that filter helped determine the age and distance of the galaxy. The twenty two aforementioned galaxies were found in this way, and thus far the distance and age of one has been identified. Star formation rates are calculated in part by looking at galaxy density and brightness, as well as the rate at which hydrogen was ionized. Star formation rates were noted to be lower between 800 milllion and one billion years post Big Bang, and ionization would have also been slow as a result. This led astronomers to conclude that the reionization epoch likely began no later than 600 million years after the Big Bang. This may seem like a contradiction but could be explained by the idea that in early galaxies, star formation was much more aggressive and resulted in bigger but fewer stars in early galaxies. Later on, there may have been more stars showing up, but they were smaller and therefore produced less ionized hydrogen.

Keep your eyes to the sky and enjoy the view!
~Lisa C.
AccuWeather.com Astronomy Center

Posted by Lisa Beightol on Monday, November 09, 2009 8:48 AM
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