This is the Dudley Observatory Skywatch Line for Monday and Tuesday, October 5th, and 6th written by Joe Slomka.
The Sun sets at 6:29 PM; night falls at 8:02. Dawn begins at 5:25 AM and ends with the Sun rising at 6:59.
The Moon rises in Taurus on both nights. Monday’s 18-day-old Moon rises at 8:32 PM, 86% illuminated and sets at 11:26 AM, Tuesday. Tuesday’s Moon rises at 9:04 PM, 78% lit and sets at 12:26 PM, Wednesday.
Sagittarius continues to house Jupiter, Pluto and Saturn. Jupiter rises first, at 2:45 PM, glows with minus 2nd magnitude, 40 arc-seconds in size, and sets at 11:42 PM. The Great Red Spot, a giant Jovian storm, is telescopically visible at 9:24 PM, Monday and at 3:11 AM, Wednesday. Wednesday, the moon IO begins to march across Jupiter’s face at 1:15 AM, followed by its shadow at 2:33; IO ends its travel at 3:31, and the shadow exits at 4:49. Dwarf planet Pluto, 4° from Jupiter, rises next at 3:03 PM, glimmers with 14th magnitude and appears as a dot in our telescopes.
Saturn rises, 7° from Jupiter, at 3:09 PM, shines with zero magnitude, and appears 17 arc-seconds. This month both Jupiter and Saturn are highest and best observed around 7:30 PM.
Mars is the main feature this month. It rises at 7:05 PM, outshines Jupiter with minus 2.6 magnitude, appears a very large 22 arc-seconds and is best observed at 1:30 AM. Tuesday finds the Red Planet at closest approach to Earth at 3.5 light-minutes, the nearest until 2035. Next week, Mars will be at Opposition, when it aligns with Earth and Sun and appears about 39 million miles from us. This is prime time to get out and observe. While the last two approaches were equally bright and large, Mars was very low in the South. This time it is about 53° high. Last week, Venus made headlines; now it is Mars’ turn. The European Space Agency’s Mars Express took radar images over the last 10 years. The images reveal a large 12-mile long lake and several smaller ones hiding under Mars’ South Polar surface. In addition, the astronomers think the water is liquid, most likely a very salty water. Again, more observations are required. There are three Mars missions now enroute and expected to land in February, so scientists will be kept busy.
Neptune rises in Aquarius at 5:36 PM, shining with 8th magnitude, 2 arc-seconds, and best observed at 11:14 PM. Uranus, in Aries, rises at 7:30 PM, brighter with 5th magnitude, an almost 4 arc-seconds in size and best observed at 2:27 AM. While Uranus can be seen in binoculars, beginners are advised to use sky charts from astronomy magazines and websites to assist in the hunt for these gas giant planets.
Venus, the last to rise, rises in Leo at 3:35 AM, blazes with minus 4th magnitude, 15 arc-seconds and 73% illuminated.
Venus, Mars and Uranus all set in daytime.
Look at Perseus’ bright star, Algol. Algol, the “Demon Star,” varies its light every 2 days, 20 hours and 49 minutes. It fades from second magnitude to third – easily seen by the naked eye. Algol dims at 7:40 PM, Tuesday. Observers should begin 2 hours before and 2 hours after minimum.