Department of Astronomy

For immediate release: July 1, 2021

BLOOMINGTON, Ind. -- The shorter nights of summer will still offer a variety of planetary events for skywatchers.

On July 11 Venus and Mars will be less than 1 degree apart low in the western sky in the constellation Leo. Venus will be about 1 degree north of Regulus, the brightest star in Leo, on July 21. Mars will pass near Regulus on July 28 and 29.

Saturn will be nearing opposition in July, rising around 10 p.m. local time on July 1 in the constellation Capricornus. The bright yellow planet will be highest in the south around 3 a.m., the best time to view it in early July. By the end of the month Saturn will reach this point two hours sooner. Its largest moon, Titan, will be visible with any telescope. Titan will be north of Saturn on July 2 and 18 and south of the planet on July 10 and 26.

Jupiter will rise an hour before midnight on July 1 and by the end of evening twilight at month's end. It will be highest in the south in the early morning hours, the best time to view it with a telescope. The huge planet will be about 20 degrees east of Saturn in the constellation Aquarius, and it will dominate this part of the sky. Jupiter will be a fine sight in telescopes, and its four Galilean moons will shine at their brightest.

Mercury will reach its greatest elongation from the sun on July 4, when it will rise 80 minutes before sunrise. Its visibility will improve as the month passes because it will brighten. Look for it 3 degrees above the eastern horizon in mid-month near the bright orange star Aldebaran in the constellation Taurus. Mercury will sink quickly during the last week of the month until it disappears into the glow of twilight.

Meteor shower

The Delta Aquariid meteor shower will peak before dawn on July 30. In a dark sky observers may see as many as 25 meteors per hour. Some meteors will appear from mid-July to mid-August. The long bright streaks will seem to come from a point in the constellation Aquarius in the southern sky.

Aphelion

Earth will reach its greatest distance from the sun for the year, called aphelion, on July 4. Those sweltering in summer heat in the Northern Hemisphere may find it hard to believe they are about 3 percent farther from the sun than they were in January. But the actual cause of the high temperatures is the tilt of Earth's axis. The part of the planet tilted toward the sun (in this case the Northern Hemisphere) is much warmer than the part tilted away, because more sunlight reaches the ground instead of being absorbed by the atmosphere.

Moon phases

The moon will be at last quarter on July 1, new on July 9, at first quarter on July 17, full on July 23, and at last quarter again on July 31.

Author: Hal Kibbey Email: hkibbey [at] gmail.com