This is Dudley Observatory’s Skywatch Line for Friday, April 29, through Sunday, May 1, written by Sam Salem.
On Friday, the Sun rises at 5:52am and sets at 7:55pm. The last quarter of the Moon occurs on Friday at 11:29pm. The half lit Moon doesn’t rise until after 2am Saturday Morning climbing in the southeast among the stars of Capricornus. The time when the Moon shows half phase is ideal for observing the Moon with a pair of binoculars or a small telescope. The mountains and craters on the Moon’s surface are presented very clearly, even though only half of the Moon’s face is illuminated. This is a time when the terminator line, which divides the illuminated and un-illuminated portions of the Moon’s disk is clearly visible. Along this line, you would see the Sun rising above the horizon illuminating the lunar landscape at a low angle, making mountains and crater rims cast long shadows, which are easy to see even through a pair of binoculars.
The Moon rises at 1:28am on Friday, 2:09am on Saturday, 2:48am on Sunday.
Jupiter is still the dominant object in the evening sky, moving very slowly against the background stars as he approaches the second stationary point in his current apparition. On Friday, Io crosses Jupiter’s face from 9:42 to 11:57 pm, followed by its tiny black shadow from 10:44 pm to 12:58 am. Europa transits the planet from 12:28 to 3:25 am, followed by its shadow from 2:47 to 5:32 am.
Mars is visible before midnight. It rises in the southeast at about 10:09 pm on Friday night. The best observing of Mars will be when it is highest in the sky. This means a few hours before dawn. Its brightness and apparent size increase dramatically this month. See Mars near its rival in the sky, the similar-colored red supergiant star Antares. Mars’ disk is now large enough to show many surface features to patient observers with modest telescopes.
The Beehive star cluster (M44) in the constellation Cancer the Crab is one of the spring sky’s finest deep-sky objects. This pretty grouping in Cancer is easy to sweep up in binoculars. It lies high in the west once evening twilight fades away. Scan the region of sky midway between Leo and Gemini to find the box-shaped quartet of stars that comprises the center of Cancer. The cluster lies near the middle. With naked eyes under a dark sky, you should be able to spot the Beehive as a faint cloud. But this star group explodes into dozens of stars through binoculars or a small telescope at low power. M44 is only about 600 light-years away, which makes it so conspicuous as one of the nearest clusters to Earth.
April 30th is the birth date of the German mathematician Carl Friedrich Gauss. Born in 1777, Gauss is ranked as one of history’s most influential mathematicians. At the age of 24, Gauss was able to successfully predict the position of the dwarf planet Ceres that disappeared and was lost to observation shortly after being discovered in 1801. Gauss worked on the problem and three months later he successfully predicted a position for Ceres that turned out to be accurate within a half-degree.