This is the Dudley Observatory Skywatch Line for Monday and Tuesday, October 12th and 13, written by Joe Slomka.
The Sun sets at 6:17 PM, night falls at 7:51. Dawn begins at 5:33 AM and ends with the Sun rising at 7:07.
The Moon resides in Leo on both nights. Monday’s Moon sets at 4:30 PM. Tuesday, the 25-day-old Moon rises at 2:47 AM, 17% illuminated, 32 arc-minutes in diameter and sets at 5:03 PM. Tuesday’s Moon appears besides Leo’s brightest star, Regulus, and 4° above Venus.
Wednesday’s slimmer Moon rises at 4:03 AM and sets in the afternoon.
Sagittarius continues to house Jupiter, Pluto and Saturn. Jupiter rises at 2:19 PM, shining with minus 2nd magnitude, appears 39 arc seconds in size, is highest at 6:48 PM and sets at 11:17. Jupiter continues to close in on Saturn, in preparation for its December 21st conjunction. The Great Red Spot (a giant storm) is telescopically visible at 4 AM, Tuesday. Wednesday, the Jovian moon IO begins to march across Jupiter’s face at 3:11 AM, followed by its shadow at 4:29 AM; IO exits Jupiter at 5:26 AM, just as Dawn begins. Pluto rises next at 2:36 PM, glimmers with 14th magnitude, appears as a tiny dot, best observed at 7:04 PM and sets at 11:32. Pluto appears equidistant between Jupiter and Saturn.
Saturn rises at 2:42 PM, shines with zero magnitude and 16 arc-seconds. It is best observed at 7:16 PM and sets at 11:51. Saturn still appears about 6° East of Jupiter, and as already mentioned, getting closer. Saturn’s moon Titan, telescopically visible, created news this week. Satellites orbiting Saturn revealed that Titan has lakes of liquid methane, that look like earthly lakes. They even have waves and a cycle of evaporation and rain, just like Earth.
Mars, the feature of the month, reaches Opposition Tuesday. It rises at 6:30 PM and is best observed at 12:54 AM. Telescopic viewers can see the Martian South Pole shrinking due to Summer, while the Martian North Pole endures Winter.
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 winter, with its polar ice cap tilted away from our view. Observers can track the South Polar Cap’s disappearing. Ice on Mars is frozen carbon dioxide gas; so, Martian ice does not melt, it reverts into gas. Opposition does not mean that Mars is closest; Mars was actually closest to Earth last week when it was 38.5 million miles away. The Red Planet orbits the Sun in about two years. 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.
Minor planet 1Ceres lies in the constellation Piscis Austrinus, near the bright star Formalhaut. Ceres shines with 8th magnitude, rises at 5:29 PM, highest at 9:52 and sets at 2:14 AM.
Neptune, 23° from Ceres, rises in Aquarius at 5:08 PM, shines with 8th magnitude, 2 arc-seconds, best seen at 10:46 and sets at 4:28 AM. Uranus, in Aries, rises at 7:01 PM, 5th magnitude, 3 arc-seconds and best seen at 1:58 AM. Uranus is also at its best this month.
Venus, in Leo, is the last to rise at 3:50 AM, blazes with minus 4th magnitude appears as a large 14 arc-seconds crescent, 75% lit. As already mentioned, it is accompanied by Regulus and the Moon, a real treat for early birds.