Mars continues its eastward trek against the backdrop of Gemini the Twins this week. Shining at magnitude 1.8, the Red Planet appears slightly fainter than the constellation’s brightest stars, Castor and Pollux. But it appears noticeably brighter than Epsilon (ε) Geminorum, the 3rd-magnitude star it passes 1° south of this evening. Mars lies nearly 15° high in the west-northwest an hour after sundown and doesn’t set until 10:30 p.m. local daylight time. If you turn a telescope on the planet, you’ll see a featureless disk that spans just 4″.
Saturday, June 1
Venus pokes above the eastern horizon about an hour before sunrise. The brilliant planet dominates the predawn sky as the rosy glow heralding the Sun’s arrival grows brighter. Venus shines at magnitude –3.8, three times brighter than the second-brightest planet, Jupiter. The inner planet looks stunning all week, but never more so than it does this morning when a waning crescent Moon lies to its right. The two stand about 6° apart and a similar distance above the horizon a half-hour before sunrise. If you view Venus through a telescope, you’ll see a disk that spans 10.5″ and appears 94 percent lit.
This is a good week to target one of the spring sky’s finest deep-sky objects. The Beehive star cluster (M44) in the constellation Cancer the Crab lies about 25° above the western horizon 90 minutes after sunset. The easiest way to find the 3rd-magnitude cluster is to look approximately 40 percent of the way from 1st-magnitude Pollux in Gemini to the similarly bright star Regulus in Leo. With the naked eye under a dark sky, you should be able to spot the Beehive as a faint cloud. But this star group explodes into dozens of stars through binoculars or a small telescope at low power.
Monday, June 3
New Moon occurs at 6:02 a.m. EDT. At its New phase, the Moon crosses the sky with the Sun and so remains hidden in our star’s glare.
Tuesday, June 4
You can use Mars as a guide to finding Mercury this week. With binoculars in hand, scan to Mars’ lower right starting about 30 minutes after sunset. Mercury shows up as a bright dot some 9° high in the west-northwest. It shines at magnitude –0.8 and appears obvious to the naked eye once you know where to look. And this evening, a two-day-old crescent Moon hangs 6° to Mercury’s left. If you keep watching as the sky grows darker, the unlit side of the Moon will grow more prominent. This is earthshine — sunlight that reflects off Earth, strikes the Moon, and then bounces back to our eyes. If you return to the scene tomorrow evening, a slighter fatter crescent Moon will lie 6° to Mars’ upper left.
Wednesday, June 5
Jupiter stands out among the background stars of southern Ophiuchus from the time it rises in the southeast shortly before 9 p.m. local daylight time until morning twilight is well underway. The giant planet is near its best for the year right now, reaching opposition and peak visibility next week (on June 10). Jupiter shines at magnitude –2.6, which makes it the brightest point of light in the sky until Venus rises about an hour before the Sun. The best time to view Jupiter through a telescope is when it climbs highest in the south, a position it reaches around 1:30 a.m. The gas giant’s spectacular disk spans 46″, and its dynamic atmosphere shows at least two parallel dark belts.
Thursday, June 6
Neptune rises before 2 a.m. local daylight time and climbs 20° high in the east-southeast as twilight commences. The distant world glows at magnitude 7.9, so you’ll need binoculars or a telescope to spot it. Fortunately, it lies near a brighter star that will guide you. This morning, Neptune stands 1.3° east-northeast of 4th-magnitude Phi (φ) Aquarii. You can confirm your sighting of Neptune through a telescope, which reveals the planet’s 2.3″-diameter disk and blue-gray color.
Look high in the northwest after darkness falls this week and you’ll be greeted by the familiar sight of the Big Dipper. The dipper is the sky’s most conspicuous asterism — a recognizable pattern of stars that doesn’t form a complete constellation shape. It represents the body and tail of Ursa Major the Great Bear. Use the Pointers, the two stars at the end of the dipper’s bowl, to find Polaris, which lies due north for everyone north of the equator. Polaris marks the end of the Little Dipper’s handle. On June evenings, the relatively faint stars of this dipper arc directly above Polaris.
The Moon reaches perigee, the closest point in its orbit around Earth, at 7:15 p.m. EDT. It then lies 228,978 miles (368,504 kilometers) away from us.
Saturday, June 8
Glorious Saturn appears conspicuous in the southeastern sky by midnight local daylight time this week. The ringed planet rises around 10:30 p.m. local daylight time and climbs highest in the south by 3 a.m. Saturn shines at magnitude 0.2 and appears significantly brighter than any of the background stars in its host constellation, Sagittarius the Archer. A telescope reveals the planet’s 18″-diameter disk and a stunning ring system that spans 41″ and tilts 24° to our line of sight.
Sunday, June 9
The conspicuous Summer Triangle asterism dominates the eastern sky in late evening. Vega, the triangle’s brightest member, shines at magnitude 0.0 and stands highest of the three stars. To its lower left lies Deneb; at magnitude 1.3, it is the trio’s faintest member. Magnitude 0.8 Altair resides at the bottom right and completes the bright asterism. Despite its name, the Summer Triangle appears prominent from late spring until winter begins.