Three planets are easy to spot in the evening sky in early June, and two of them are real showpieces, if you happen to have access to a telescope: Jupiter, with its four satellites discovered by Galileo, and its two dark cloud belts; and Saturn, with its spectacular rings.
June 2014 at dusk: The six brightest starlike objects visible at duskare Jupiter (the brightest, of magnitude -1.9 to -1.8); Mars (magnitude -0.5 to 0.0); the stars Arcturus, Vega and Capella (all near 0.0); and Saturn (+0.2 to 0.4). (The lower the magnitude number is, the brighter the object.)
Stars appear to twinkle noticeably, because of the Earth’s atmosphere. The planets generally shine with a steadier light, because they are close enough to Earth to show a disk, at least when seen through a telescope. Each point of the planet’s disk twinkles like a star, but if you add up the light from all the points, the sum is relatively constant.
June’s easily observed evening planets include Jupiter, sinking nearly to the west-northwest horizon, preparing to depart; Mars,in the south to southwest; and Saturn, ascending in the southeast to south. Mercury now requires binoculars; it sinks into the bright west-northwest twilight glow very early in the month while fading sharply, from magnitude +1.4 to +2.1, June 1-5. When you see three or more planets widely spaced in the sky, as they are in June, notice how they seem to lie in a nearly straight line across the sky: A line from Jupiter to Mars extended points to Saturn.
In what remains of winter’s collection of stars, Procyon, the “Little Dog” star, departs in the west early in June; Capella, already low in the northwest at the start of June, exits as well. Pollux and nearby Castor, not quite of first magnitude and therefore not shown on our twilight chart, are the last bright winter stars lingering well into June; look for these “Gemini Twins” to the upper right of Jupiter. Regulus, heart of Leo, is in the west-southwest to west, to the upper left of Jupiter. Blue-white Spica, spike of wheat in the hand of Virgo, and golden Arcturus, the “Bear Guardian” star in Bootes, the Herdsman, pass their high points in the south. Reddish Antares, heart of Scorpius, ascends in the southeast. Altair rises north of east to the lower right of Vega and Deneb, completing the Summer Triangle with them, in time for the season’s beginning.
Follow the waxing moon in the evening sky as it passes near these planets and bright zodiacal stars:Jupiter on June 1; Regulus on June 3 and 4; Mars on June 7; Spica on June 8; Saturn on June 9 and 10; Antares on June 11; and Jupiter again on June 28—but this time with the moon very low in bright twilight.
For planet-watchers: Watch the bent line of Jupiter-Pollux-Castor straighten as June progresses. The “twin” stars are 4 1/2 degrees apart, and Jupiter passes 6 degrees to the lower left of Pollux at mid-month. Follow Mars closing in on Spica all month. On June 1, Mars and Spica are 14 degrees apart; on June 30, they’re within 6 degrees.
On July 5, the moon, just past first-quarter phase and a little more than half illuminated, will pass between Mars and Spica while they’re within 4 degrees. In a colorful pairing on July 13, the red planet will pass just 1.3 degrees north of the blue-white star.
June 2014 at dawn: Venus at magnitude -4 is the only naked-eye planet up in morning mid-twilight. This brightest morning “star” appears low in the east to east-northeast during June. Next in brightness are three stars, all of magnitude zero: golden orange Arcturus, setting in the west-northwest; blue-white Vega, just west of overhead; and yellowish Capella, low in the northeast, ascending as the month progresses.
Other stars: Altair and Deneb, joining Vega to complete the Summer Triangle overhead; Fomalhaut, low in the southeast to south; Antares, heart of Scorpius, setting in the southwest early in month; and Aldebaran, eye of Taurus, emerging below Venus late in the month.
The waning crescent moon in the morning sky passes near Venus on June 24, within 2 degrees, and well worth getting up early to see! Note the beautiful Pleiades star cluster (aka Seven Sisters) 6 degrees to the upper left of Venus on June 23-25. The thin old moon appears to the lower left of Aldebaran, eye of Taurus the Bull, on June 25. Venus will pass just 4 degrees north of Aldebaran on July 1. The view of Venus, Aldebaran and the Hyades star cluster in binoculars early that morning will be breathtaking!
Many beautiful sights await you this summer, in both morning and evening skies. Mark the date Aug. 18 on your calendar, to remind yourself to get up early for a spectacular close predawn pairing of the two brightest planets, Venus and Jupiter. The June through September issues of the Abrams Planetarium Sky Calendar will provide illustrations of the best gatherings. Those issues won’t be put online, but you can get information on how to subscribe at www.pa.msu.edu/abrams/skycalendar.
Check the website of the Astronomical Society of the Desert (www.astrorx.org) for dates and locations of “star parties,” where everyone is welcome to look through our telescopes at the moon, planets and “deep sky objects.” Our sky watches at the National Monument Visitor Center will resume in October, while our monthly sessions at Sawmill Trailhead, at 4,000 feet, continue all year.
Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs, Calif. Robert D. Miller, who provided the twilight charts, did graduate work in planetarium science and later astronomy and computer science at Michigan State University. He remains active in research and public outreach in astronomy.