This is Dudley Observatory’s Skywatch Line for Friday, September 2, through Sunday, September 4, written by Sam Salem.
The Sun rises at 6:22am and sets at 7:28pm on Friday. Try to locate the young waxing crescent Moon and Jupiter in the western sky shortly after sunset. Venus, shining above the crescent Moon and Jupiter, should be a little easier to spot than Jupiter this evening. Use binoculars or a wide-field scope to start looking for the thin crescent Moon near Jupiter and Venus in the bright sky just above the west-southwest horizon. Venus outshines Jupiter and stays out a little later after sunset. The waxing crescent Moon sets at 8:12pm, Jupiter sets at 8:11pm, and Venus sets at 8:24pm on Friday evening. The crescent Moon will be much easier to spot on Saturday evening as the, then 5% illuminated, waxing crescent Moon sets at 8:40pm. Try to spot the crescent Moon, Venus, and Jupiter low in the Western sky 30 minutes after sunset. On Sunday evening, the slender crescent Moon shines quite close to star Spica, the brightest in the constellation Virgo, the Maiden.
Jupiter will exit the evening sky to enter the morning sky in late September while Venus will remain bright in the evening sky until March of next year. Day by day, Venus is climbing upward, toward Saturn, while Saturn is descending sunward, toward Venus. Venus will meet up with Saturn in a conjunction on October 30.
This weekend is good for observing Neptune. The most distant known planet is at opposition on Friday. Opposition occurs when the Sun, Earth, and a superior planet, a planet that orbits the Sun outside Earth’s orbit, are approximately in a straight line. Earth and Neptune will be in the same direction as seen from the Sun. At opposition, the planet is visible almost all night, reaching the highest altitude around midnight and setting around sunrise. This weekend, Neptune rises around 7:24pm and sets around 6:29am. At that point in its orbit, where Neptune is roughly closest to Earth, the planet appears bigger, brighter, and nearly completely illuminated as we see a “full planet”, analogous to a full Moon. The far planet is up all night at its brightest at magnitude 7.8. Neptune is bright enough to be viewed in binoculars and small telescopes. Neptune transits the meridian (the imaginary line that joins north and south, and passes directly overhead) a little before 1:15am. The planet is currently making its way through the constellation Aquarius. The planet is positioned just a little more than one degree southwest of lambda (λ) Aquarii. In a telescope, the planet looks like a pale, blue-green point of light.
On September 3,1976, the unmanned spacecraft Viking 2 landed on Mars and took the first pictures of the Marian surface. Viking 1 was the first to arrive on the surface of Mars on July 20, 1976. The two identical spacecraft, Viking 1 & Viking 2, each consisting of a lander and an orbiter, flew together and entered Mars orbit. Viking 2 lander settled down at Utopia Planitia, while the Viking 1 lander touched down on the western slope of Chryse Planitia (the Plains of Gold). The landers examined the Martian soil and analyzed its atmosphere and weather. In addition, the two landers conducted three biology experiments designed to look for possible signs of life. These experiments discovered enigmatic chemical activity in the Martian soil, but provided no clear evidence for the presence of living microorganisms in soil near the landing sites.