The “King of the Planets” certainly lives up to that title in May. Jupiter glows brilliantly at dusk in the southeast part of the sky. Meanwhile, a much dimmer Mars is on the opposite side of the sky, low in the west-northwest.
While Jupiter is in view through much of the night, you’ll have to look quick for Mars before it drops out of sight below the horizon during mid-evening. Beautiful Saturn gradually makes its entry into the early evening sky, appearing low in the southeast before the last vestige of evening twilight disappears by the end of the month. [Sky Maps for the May 2017 Night Sky ]
And if you miss seeing Venus in the evening, all you need do is wake up two hours before sunrise and face east. Mercury proves to be a challenge, lying very low just above the east-northeast horizon about a half hour before sunrise, but is very tough to spot unless you have access a clear, unobstructed horizon and good binoculars .
In our night sky planets schedule, remember that when measuring the angular separation between two celestial objects, your clenched fist held at arm’s length measures roughly 10 degrees. Scroll down for our schedule below which provides some of the best planet viewing times as well directing you as to where to look to see them. You can see our full night sky observing guide for May here .
Mercury –the planet nearest to the sun, reaches a greatest elongation of 26 degrees on the morning of May 17, the farthest west of the sun it gets in 2017. Yet this is the year’s worst morning apparition for northerners, because the ecliptic then forms a small angle with the predawn horizon. For the rest of May, Mercury is only 1 degree above the horizon in mid-twilight (about 50 minutes before sunup) for latitude 40 degrees north. Scan the horizon with binoculars about 15 degrees north of due east. From southern states, Mercury will be a few degrees higher and possibly accessible to the unaided eye, and if you live in the Southern Hemisphere it is comfortably well up in the east as dawn brightens.
During May, Venus shines brightly in the eastern pre-dawn sky amid the stars of western Pisces. The planet’s disk will appear as a thin crescent that waxes toward a half-lit phase through the month while shrinking in apparent diameter. Due to a shallow morning ecliptic, Venus will not climb very high above the horizon before the sun rises. On Monday morning, May 22, Venus and the old crescent moon will rise together about 4 am local time, with the moon about 4 degrees to the lower right of the bright planet.
Credit: Starry Night
Venus – is the dazzlingly bright Morning Star for this spring and summer. Look for it low in the eastern sky. Venus attained its greatest brilliancy (magnitude -4.7) for the year on April 30, but it is practically at that level of brightness now. Observe the planet in a telescope as Venus thickens from a 27-percent illuminated crescent to become almost half-lit (48-percent) by month’s end, shrinking all the while. On May 22, early risers should check out the eastern sky after 4 a.m. local daylight time to catch sight of a lovely crescent moon and shining to its upper left will be Venus.
All month, reddish Mars remains in the western early evening sky amid the stars of Taurus. Although setting shortly after 10 pm local time, it will steadily descend into the evening twilight. It continues to drop in brightness and disk size as we pull farther away from it.
Credit: Starry Night
Mars –is now on the far side of its orbit from us, and has dimmed to 2nd-magnitude on the brightness scale used by astronomers and sets only two hours after the sun in mid-May. Nevertheless, observers with binoculars can locate it to the upper right of the brighter orange-hued Aldebaran, the two objects being 6 degrees apart this evening. As May opens, Mars is still an easy naked-eye object at dusk in the west-northwest. This week it sets shortly after the end of astronomical twilight, just over two hours after sunset. But with each passing day the sun gains nearly one-third of a degree on Mars in their eastward race along the zodiac , so within a few weeks the Red Planet will be sinking deep into bright twilight.
On Sunday, May 7, Jupiter, the nearly full moon, and the bright star Spica will appear together in the eastern sky starting about 6:30 pm local time. The moon and Jupiter will fit within a binocular field of view and make a nice photo opportunity. The three objects will cross the night sky together and be visible low in the western sky before 5 am local time.
Credit: Starry Night
Jupiter – was at opposition in early April , so in May it remains very bright and slightly larger than usual in telescopes. This month this giant planet drifts even farther away from bluish Spica, the brightest star in the constellation Virgo. Jupiter is high enough to appear sharp in telescopes until well after midnight. A medium-sized instrument can show numerous features in the forever-changing clouds of Jupiter’s face . On the evening of May 7, as the sky darkens, direct your attention toward the southeast, where you’ll see a waxing gibbous moon. And sitting less than 3 degrees to its right will be Jupiter.
Saturn —The famous ringed planet, glowing in the constellation Ophiuchus , rose in the east-southeast two hours after darkness fell on May 1. By the end of the month, it comes up while the last glimmers of twilight remains in the west. In a telescope magnifying at least 30-power, Saturn tilts its rings spectacularly wide open to our view.
Can you see any difference in color between the inner and outer rings ? The outer ring has a noticeably duller hue. How far around can you follow Cassini’s Division , the dark line dividing the two main rings? How many belts, if any, can you make out on the planet itself? Seldom do Saturn’s belts show the breaks and knots of their Jovian counterparts. On May 13 at around 11 p.m. your local time look low toward the southeast for the waning gibbous moon slowly rising and accompanied about 2.5 degrees to its right by Saturn, shining like a very bright yellowish-white “star.”
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, and he is also an on-camera meteorologist for Fios1 News in Rye Brook, NY. Follow us @Spacedotcom , Facebook and Google+ .