This is Dudley Observatory’s Skywatch Line for Friday, July 10, through Sunday, July 12, written by Sam Salem.
On Friday, Sun rises at 5:27am and sets at 8:34pm; Moon sets at 10:52am. On Sunday, the Moon will reach its last quarter phase at 7:29pm. At last quarter, the Moon rises around midnight (Standard Time) and remains visible in the southern sky during morning daylight.
In the southeastern sky during the hours before dawn on Saturday, the Moon will shine near Mars. Look for the waning gibbous Moon positioned a palm’s width of the bright, red planet. As the pair crosses the sky together, the Moon’s orbital motion will carry it noticeably closer to Mars by dawn. The same movement will cause the Moon to hop to the left-hand, or eastern side, of Mars on Sunday morning. Mars, at magnitude -0.6, rises due east around 1am, shining at the border of constellations Pisces and Cetus. In a telescope Mars has grown to 12 arc-seconds in apparent diameter. Mars will grow to 22.6 arc-seconds wide when it passes closest by Earth around opposition in the first half of October.
Venus will reach -4.47 magnitude for the current morning apparition, in the early hours of Friday. In a telescope, the planet will show a 27 percent illuminated waxing crescent phase and an apparent disk size of 37 arc-seconds. Even with a less than fully-illuminated disk, Venus’ nearness to Earth will boost its brightness. After rising at about 3am, the extremely bright planet will be visible in the eastern pre-dawn sky, just above the bright orange star Aldebaran in constellation Taurus. Venus’ trip through the triangular face of Taurus, the Bull will be concluding on Sunday, when the bright planet passes less than a finger’s width to the upper left of Aldebaran. Look for the star and planet sitting above the eastern horizon together for about two hours before dawn. Look 12 degrees up to see the Pleiades.
The Moon passes 4 degrees south of Neptune at 3am, on Friday. At that time, the planet is nearly 30 degrees high in the southeast, hanging against the stars of Aquarius. The magnitude 7.9 ice giant is an ideal binocular object this month, although the bright nearby Moon may make it a bit of a challenge to pick out this Friday morning. Swing about 16.5 degrees due east of Neptune to spot Mars, which will be much easier to find. The magnitude 5.8 Uranus, in constellation Aries, is up in the east just before dawn, about midway between Venus and Mars.
Jupiter and Saturn rise in twilight, loom low in the southeast after dark, and climb as the evening grows late. Saturn is about 6 degrees to Jupiter’s lower left. Farther to Jupiter’s right is the Sagittarius Teapot. The two planets are highest around 1am.