PhysOrg.com | Space Exploration | 05 July 2010
The western sky will be crowded after sunset in July. Forming a long slanting line from highest to lowest above the horizon will be the planets Saturn, Mars and Venus, with the bright star Regulus included as well.
Photo courtesy of NASA
Brilliant white Venus will dominate the scene, shining low in the west-southwest an hour after sunset. The gleaming planet will be 40 times brighter than the most conspicuous stars in the evening sky. Venus will become even more dazzling as the month passes, far outshining the stars of the constellation Leo the Lion as it moves among them. On July 9, Venus will be just a degree north of Leo's brightest star, Regulus. By month's end, Venus will be closing in on Mars and Saturn to its upper left (south).
Mars, a hundred times fainter than Venus, will be easy to identify by its red-orange color, contrasting with the pale yellow of Saturn farther to the left. The two will be well separated at the start of the month, but the gap between them will close rapidly, and they will be only a couple of degrees apart at month's end. Mars will not show much detail in a telescope, but Saturn's rings and larger moons will put on a good show starting about an hour after sunset.
Around the middle of the month, Mercury will emerge from the afterglow of sunset low in the west-northwest, adding a fourth planet to the celestial chorus line. Mercury will be very close to Regulus on the evening of July 27. Binoculars may be needed to see this conjunction.
Jupiter will rise around the time Saturn sets, a little after midnight at the start of the month and about 10:30 p.m. EDT by month's end. Appearing well above the eastern horizon as a beautiful "morning star" in the brightening sky, Jupiter will get higher and brighter as the month passes. Its four largest moons will be on the same side of the planet on July 5, 8 and 18.
