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Hal Kibbey

Last modified: Friday, June 28, 2013

Star Trak: July 2013

June 28, 2013

BLOOMINGTON, Ind. -- At the beginning of July, the first planet to appear as the evening sky darkens will be Venus, visible near the western horizon about a half hour after sunset. As Venus moves away from the sun during the month, it will move mostly southward along the horizon, not higher in the sky. On July 3, Venus will pass through the background stars of the Beehive Cluster, though the star cluster will be hard to see in twilight.


Photo courtesy of NASA

During the third week of the month, Venus will close in on the bright white star Regulus in the constellation Leo the Lion, and on the evenings of July 21 and 22, the two brilliant objects will be only about 1 degree apart. The planet will be more than 100 times brighter than the star, but the pair will be a beautiful sight in binoculars.

As twilight fades, Saturn will appear almost halfway up the southwestern sky. By 10 p.m. local time it will be about 30 degrees above the horizon, and it won't set until after midnight, offering observers with telescopes a couple of hours of good viewing on a clear night. Seen through a telescope, Saturn's rings will be tilted 17 degrees to our line of sight this month. The planet's largest moon, Titan, will be north of it July 1 and 17 and south of it July 9 and 25.

Mars and Jupiter will have a close encounter low in the east-northeast July 22, passing less than 1 degree apart 45 minutes before sunrise. The two planets will be visible in the same field of view of a telescope at low power, highlighting the great contrast in their colors. By coincidence, this conjunction in the eastern sky will happen on the morning after the evening conjunction in the western sky between Venus and Regulus.

Mercury will be too low and faint in morning twilight to be visible until the last week of July. Then it will brighten quickly, reaching its greatest height above the east-northeastern horizon July 30, when it will be 8 degrees below Mars.

Meteor shower

The southern branch of the Delta Aquarid meteor shower will peak before dawn July 30. The third-quarter moon will rise around midnight local time and will wash out some of the "shooting stars," but occasional bright meteors will be visible in a clear sky. Meteors will appear several nights before and after the peak as well. The long bright streaks will seem to come from a point in the constellation Aquarius in the southern sky during the hours just before morning twilight.


On July 5, Earth will reach its greatest distance from the sun for the year, called aphelion. 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.

Those experiencing winter in the Southern Hemisphere will not be surprised to hear that. But the difference is actually caused by 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 new on July 8, at first quarter on July 15, full on July 22 and at third quarter on July 29.