Ladd Skies: Dec 16, 2014 Once again, all we can seem to view overhead are clouds today, so Ladd will be closed this evening; however, please keep looking up as often as the skies allow. You’ve probably noticed the “sign” of winter, Orion, the Hunter, is rising earlier with each passing night. Also, directly above, or to the north, of him, is Gemini, the Twins, with their so-called twin stars marking their heads, Castor and Pollux, although Pollux is a tad brighter. To remember which head is which, just recall the alphabet: C comes before P, C(astor) rises before P(ollux). Each twin’s body is a stick-figure shape, going downward toward Orion. Gemini was very important last weekend, as the Geminid meteor shower has its apparent origin, or radiant, just to the right, or west of Castor’s head. Although the peak observing has passed us by, keep watching, as there just may be some leftover shooting stars still to be enjoyed. Let us know if you are able to observe any. The Moon is very easy to find early in the mornings this week, as it is in its waning crescent phase, on its way to Sunday’s New phase. If you’re up early this week, don’t forget to look for the Earthshine, the Earth’s reflected sunlight striking the dark side of the Moon. Also, the Moon will be joined in the sky both Friday and Saturday by our favorite ringed planet, Saturn. On Friday morning, Saturn will be to the lower left of the Moon, and Saturday morning, the very thin waning crescent will be to the lower left of Saturn. Although we might be already getting tired of the cold, winterlike conditions, I’m sorry to let you know that winter hasn’t officially started yet. Seasonal changes are actually caused by the position of the Sun in its apparent path across the sky. That path, the ecliptic, is inclined 23 ½ degrees to our Earth’s equator; therefore, there are times when the Sun appears very high in our sky, giving us our summertime, and times when it almost seems not to be in the sky at all, as it is positioned very low for us. The “lowest” Sun day this year will be this Saturday, when about 6:03 P.M. the Sun will reach its lowest point, 23 ½ degrees below the equator. One of the more “forgotten” mission when speaking about outer planet exploration is Galileo, launched in October, 1989 by the Space Shuttle Atlantis. This mission was supposed to have been launched three years earlier, on the mission right after the Challenger; because of this, its three-year flight to Jupiter took six. Despite that time lag, though, and the fact that it had problems with its antenna system, Galileo sent back an amazing amount of new information. On its way to Jupiter, it passed the asteroid Gaspra, and found its satellite Ida, the first asteroid/moon system ever imaged. It was in line to observe Comet Shoemaker-Levy 9 as its pieces crashed into Jupiter. Galileo, which was made to orbit Jupiter, also released an entry probe, which sent us the first information on conditions within the giant planet’s upper cloud layers. In addition, on this day in 2000, information was released that Jupiter’s largest moon – and the largest in the entire solar system – Ganymede, appeared to have a liquid saltwater ocean beneath its surface. Galileo was retired three years later, after an eight-year stint at Jupiter, by having it fly into the planet, just as its probe had done years before. Ladd will be closed for the holidays the next two weeks, December 23rd and 30th, but you will be receiving our notes, as we do hope you will continue to enjoy observing the sky. Hope to see you all in the new year. Francine Jackson, Staff Astronomer
Posted on: Tue, 16 Dec 2014 17:18:50 +0000
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