STAR TRAK: Mercury first planet to be seen through most of July
For the first three weeks of July, the first planet to appear in the evening sky will be Mercury, visible near the west-northwestern horizon around 45 minutes after sunset. After that, the planet will rapidly fade as it disappears into the glow of twilight. On the evening of July 6, Mercury will pass through the Beehive star cluster, but only viewers to the south will have a good chance to see this, even with binoculars.
About an hour after sunset, Saturn will appear about a third of the way up the west-southwestern sky. Viewed through a telescope, the planet's rings will start to become more noticeable this month as they tilt more to our line of sight. Saturn's largest moon, Titan, will be farthest east of the planet on July 1 and 17, and farthest west on July 9 and 25.
Jupiter will rise around 2 a.m. EDT (6:00 Universal Time) at the start of the month and two hours earlier by month's end. By dawn it will be high in the southeast, almost 10 times brighter than any star visible before dawn. The best telescopic views will be an hour or two before the start of morning twilight. Jupiter's four brightest moons can be followed with any telescope as they orbit the planet at different rates.
Well to the lower left (east) of Jupiter, Mars will change the appearance of the constellation Taurus the Bull during July as it passes among those stars. Rising in the east-northeast before morning twilight begins, the Red Planet will be fainter than the constellation's bright red-orange star Aldebaran.
Venus will appear very low in the east-northeast about an hour before sunrise in early July, visible in bright twilight only because of its brilliance. It will disappear into the sun's glow by the second week of the month, remaining out of sight until late September .
The southern branch of the Delta Aquarid meteor shower will peak before dawn on July 30, when the new moon will offer ideal viewing conditions. 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 the Water-bearer in the southern sky during the hours just before morning twilight. In a dark sky there may be as many as 20 meteors per hour at the peak.
On July 4, 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 that they are about 3 percent farther from the sun than they were in January. Those experiencing winter in the Southern Hemisphere will be easier to convince. The difference is caused by the tilt of Earth's axis. The part of the planet tilted toward the sun is much warmer than the part tilted away, because more sunlight reaches the ground instead of being absorbed by the atmosphere.
The moon will be new on July 1, at first quarter on July 8, full on July 15, at third quarter on July 23 and new again on July 30.