This is the Dudley Observatory Skywatch Line for Monday and Tuesday, April seventh and eighth written by Joe Slomka The Sun sets at 7:28 PM; night falls at 9:08. Dawn breaks at 4:46 AM and ends with sunrise at 6:25. The First Quarter Moon dominates the darkening sky and appears moderately high in the Southeast. The half-lit Moon inhabits Cancer both nights. However, the Moon’s brilliance washes out the “Beehive” star cluster that also graces Cancer. The Moon sets at about 3 AM on both days. Jupiter lies higher above the Moon, in Gemini. Monday evening, binocular observers can witness the Jovian moon Io reappear from behind Jupiter; they can also see, through their telescopes, Io’s shadow exit the face of the giant planet at 11:43 PM Tuesday. Mars rises at sunset and sets at sunrise. The Red Planet appears in Virgo, just above the bright star Spica. Mars is at Opposition on Tuesday evening. This means that Mars is in a direct line through Earth and to the Sun. Opposition is the best time to observe any planet, but Mars is always special. A good telescope with moderate powers can show actual surface features. Astronomy magazines and websites provide Martian surface maps. Mars’ northern hemisphere is now experiencing its six-month summer, with its polar ice cap tilted in our direction. Observers can track the polar ice cap disappearing. Ice on Mars is frozen carbon dioxide gas; so, Martian ice does not melt; it turns into gas. Opposition does not mean that Mars is closest; Mars is actually closest to Earth on April 14th, when it is 57.4 million miles away. Mars orbits the Sun in about two years; the next two oppositions will be closer, but lower on the horizon and more difficult to see. Mars has two moons, Phobos and Deimos. These are challenge objects for astronomers who have larger telescopes, high powers and detailed star charts. If one does not have a telescope, one can still see Mars. The Curiosity rover, still active on Mars, routinely sends back pictures of Martian terrain; the Mars Reconnaissance Orbiter also beams high altitude pictures of Mars. Both are available on NASA websites. Saturn, by Midnight, is high enough in Libra for observation of its glorious rings. Venus rises at Dawn, and by civil dawn, is high enough for observation. Venus appears half-illuminated in a telescope. The gas giant planet Neptune lies four degrees to Venus’ east and represents another challenge for the observer. Mercury rises at 6 AM and is quite low on the eastern horizon.
Posted on: Sun, 06 Apr 2014 20:07:20 +0000
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