Skywatch Line for Friday, August 5, through Sunday, August 7, 2022

This is Dudley Observatory’s Skywatch Line for Friday, August 5, through Sunday, August 7, written by Sam Salem.

On Friday, Sun rises at 5:51am and sets at 8:11pm; Moon rises at 2:02pm. First-quarter Moon occurs at 7:07am on Friday. After dark the Moon shines in central of the constellation of Libra. Stars Delta Scorpii, and then brighter Antares are to Moon’s left. Spica is farther to its lower right, and Arcturus shines even farther to the Moon’s upper right.

The Moon is in a waxing gibbous phase on Saturday and Sunday, more than half lighted but less than full. The moon will be bright in our sky as evening falls. On those evenings you’ll find the bright Moon near reddish Antares, the Heart of Scorpius the Scorpion. A red-looking star that you can see with the unaided eye is either a red giant or a red supergiant star. Antares is a red supergiant. On Saturday after dusk, the waxing gibbous Moon will shine in western Scorpius, between Antares, and the up-down row of small white stars that form the scorpion’s claws, Jabbah or Nu Scorpii, Graffias or Acrab, Dschubba, Pi Scorpii and Rho Scorpii. Use a telescope to reveal that Nu Scorpii, Graffias and Dschubba are close-together double stars.

At first quarter, the Moon rises around mid-day and sets around midnight. It is visible in the afternoon daytime sky. The evenings surrounding first quarter are the best ones for seeing the lunar terrain when it is dramatically lit by low-angled sunlight, especially along the terminator, the pole-to-pole boundary that separates the lit and dark hemispheres. On Sunday night, the terminator on the waxing gibbous Moon will fall just west of Sinus Iridum, the Bay of Rainbows. That semi-circular feature is a large impact crater that has been flooded by the same basalts that filled the much larger Mare Imbrium to its east, forming a rounded “handle” on the western edge of the mare. The “Golden Handle” effect is produced when low-angled sunlight brightens the prominent Montes Jura Mountain range surrounding Sinus Iridum on the north and west. Sinus Iridum is almost craterless but hosts a set of northeast-oriented wrinkle ridges that are revealed at this phase.

Mercury is very low and bright, about -0.5 magnitude, in the glow of sunset. Try locating Mercury, about 30 minutes after sunset, with binoculars just above the horizon a little to the right of due west.

Venus, magnitude –3.9 in Gemini, continues to rise just as dawn begins. As dawn brightens, look for it low in the east-northeast. It’s far below Capella.

Mars, magnitude +0.2 in Aries, rises around 1am and shines high in the east-southeast as dawn begins. It rises about four fists lower left of Jupiter. By dawn they’re high in the south, with Mars now directly left of Jupiter. Uranus, magnitude 5.7 in Aries, is in the background of Mars.

Jupiter rises due east around 11 pm, shining at a magnitude –2.7 at the Pisces-Cetus border. It’s highest in the south as dawn begins.

Saturn, magnitude +0.4 in western Capricornus, is very low in the east-southeast in late twilight. It is at its highest and best in the south around 1am. Saturn’s rings appear roughly as wide, end to end, as Jupiter’s disk.

Neptune, magnitude 7.9 at the Aquarius-Pisces border, is high in the south before the first light of dawn, west of Jupiter.

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