Venus, as usual, shines brilliantly through the evening twilight, but continues to flounder low near the west-northwest horizon through July. You can use it, however, to help locate the much dimmer Mars during the second week of July. In addition, a narrow crescent moon will be in their vicinity on July 11, then both planets engage in a tight conjunction the following night.
Mars will be more than 5.5 magnitudes dimmer than Venus, so to get the very best view, you should use binoculars. During the late evening hours, after Venus and Mars have set, attention will turn to the east-southeast where Saturn and Jupiter will call attention to themselves amidst the dim stars of the constellations Capricornus and Aquarius. On July 24, the waning gibbous moon forms a wide triangle with Saturn on the right and Jupiter on the left, and late the following evening, Jupiter will hover directly above the moon. As the night is coming to an end, we can look for little Mercury which will be positioned low to the east-northeast horizon about 45 minutes before sunrise during the first half of the month.
In our schedule, remember that when measuring the angular separation between two celestial objects, your clenched fist held at arm's length measures roughly 10 degrees. Here, we present a schedule below which provides some of the best planet viewing times as well directing you as to where to look to see them.
Mercury
Mercury stands at greatest elongation west (22 degrees from the sun) on Independence Day morning, but this apparition is unfavorable for observers in mid-northern latitudes. Look for it with binoculars 45 minutes before sunrise just above the east-northeastern horizon. It's 11 degrees to the lower left of the star Aldebaran and 26 degrees to the lower right of Capella. The planet's magnitude is +0.5 and a telescope shows its small globe 35% illuminated. For the next two weeks as this speedy planet brightens to magnitude -1, it can be seen much more easily as more of its lighted side is turned toward us. But late in the month it will quickly move into the glare of the sun, passing superior conjunction (on the sun's far side) on Aug. 1. On the morning of July 8, an exceedingly narrow (3% illuminated) waning crescent moon will be positioned about 4.5 degrees to the left of Mercury. Binoculars will be most beneficial in your attempt to make a sighting.
Venus
Venus sets 1.5 hours after the sun all summer for viewers at mid-northern latitudes. It stands only about 10 degrees above the western horizon by the time it is plainly visible a half hour after sundown. That's so low that it's difficult for telescopes to show that its rather small disk is slightly gibbous. When July starts, a much fainter Mars will be roughly 7 degrees to the upper left of Venus. With each passing night, Venus will creep a bit closer and on the evening of July 11 — the night before their conjunction — a waxing crescent moon will pass about 6 degrees to their right. Mars will appear 1 degree to Venus's left. On July 21, Venus appears 1.1 degrees to the upper right of the 1st-magnitude heart of Leo, Regulus. Venus shines at magnitude -3.9, 130 times brighter than the star. Regulus should be visible to the naked eye if your sky isn't too hazy. Binoculars and small telescopes will show the pair beautifully.
Earth
Earth arrives at aphelion, which is that part of its orbit which places it farthest from the Sun on July 5 at 6:27 p.m. EDT (2227 GMT), a distance of 94,510,886 miles (152,100,527 kilometers).
Mars
Mars is in its final month of evening visibility before it disappears into the sunset fires. Use Venus to locate it during the second week of July as it hovers in the general vicinity of dazzling Venus; both quite low in the western sky about a half hour after sunset. On July 12 Venus and Mars appear closest together, separated by only 0.6 degrees. Venus is 190 times brighter and almost overwhelms Mars with its brilliance. Then, on July 29, in the western evening sky, eight days after it was visited by Venus, Regulus now has a close brush with Mars. But as seen from latitude 40 degrees north the pair will set a half-hour before twilight ends and so will be difficult to observe. You'll need binoculars to see this second magnitude planet just 0.6 degrees to the upper right of brighter Regulus (magnitude +1.4). Optical aid will show the contrasting colors of bluish white Regulus and orange-gold Mars, accentuated by the objects' proximity to each other. Telescopes will barely reveal Mars's tiny disk, now only one-fifth as wide as it appeared during the planet's close approach last October.
Jupiter
Jupiter, located in the constellation Aquarius (the water carrier), rises in the east-southeast ever earlier as July progresses, but it's not at its highest in the south until the predawn hours. This month the king of the planets brightens to an imposing magnitude -2.8 and swells in size as it nears opposition on Aug. 19. On the evening of July 25, just prior to midnight you'll see Jupiter shining about 5 degrees directly above the waning gibbous moon.
Saturn
Saturn, which is in Capricornus (the sea goat), rises during evening twilight all month. At the beginning of July, it takes until about 12:30 a.m. local daylight time to reach an altitude of 20° or so, shining in the southeast sky. By month's end it's there as early as around 10:30 p.m. On the evening of July 24, you'll find it 8 degrees to the upper right of the nearly full moon. Saturn is due to reach opposition on Aug. 2.
Space calendar: Rocket launches, sky events, missions & more!
Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmers' Almanac and other publications in New York's lower Hudson Valley. Follow us on Twitter @Spacedotcom and on Facebook.
