Venus (upper left) and Jupiter appeared near each other at the end of January 2008. The two brightest planets should look equally spectacular in late May. // Mike Salway
Friday, May 24
Mercury passes 1.4° north of Venus this evening (officially at midnight EDT), and the two make an attractive pair in the western sky during twilight. From the Northern Hemisphere, Mercury appears to the upper right of its brilliant neighbor. Nearby Jupiter adds to the scene from its perch less than 5° to the pair’s upper left. From now through May 29, the three planets remain within 5° of one another and will fit in the field of view of most binoculars.
Full Moon occurs at 12:25 a.m. EDT tomorrow morning (9:25 p.m. PDT this evening), but our satellite looks completely illuminated all night. You can find it rising in the southeast around sunset and peaking in the south at 1 a.m. local daylight time. The Moon lies among the background stars of northern Scorpius, just over 5° from 1st-magnitude Antares. An essentially undetectable penumbral lunar eclipse also occurs tonight. A mere 1.6 percent of the Moon dips into the fringe of Earth’s outer shadow. The eclipse starts at 11:53 p.m. EDT and lasts 34 minutes.
Saturday, May 25
The three evening planets now lie within 3° of one another, with Jupiter to the left and slightly above Mercury and Venus. The trio stays packed within a 3° circle through May 27, although their positions relative to one another will change noticeably each night.
The Moon reaches perigee, the closest point in its orbit around Earth, at 9:43 p.m. EDT. It then lies 222,685 miles (358,377 kilometers) away from us. Because perigee arrives less than 24 hours after Full Moon, residents of coastal areas should expect higher than normal tides for a few days.
Sunday, May 26
For viewers in North America, our evening trio of planets packs closest together tonight. All three lie within a circle just 2.5° in diameter (the width of five Full Moons). Venus shines the brightest (magnitude –3.9), with dimmer Mercury (magnitude –0.8) directly above it and intermediate Jupiter (magnitude –1.9) to their left.
Venus and Jupiter stand side by side May 27, with Mercury glowing more dimly just above them. // Astronomy: Roen Kelly
Monday, May 27
Venus and Jupiter appear side by side in this evening’s sky, with brighter Venus to the giant planet’s right. And don’t forget Mercury, which this evening lies directly above the other two. The separation among the three has increased only slightly (by 0.1°) since yesterday.
Comet PANSTARRS (C/2011 L4) continues to dim this week, and you’ll need a telescope to follow its trek back into the solar system’s depths. Fortunately, its position near Polaris — it currently stands some 5° from the 2nd-magnitude Pole Star — means that it remains on view all night for observers in the Northern Hemisphere. Tonight and tomorrow night, the comet’s orbital plane tilts edge-on to our line of sight, which will cause its dust tail to appear dense and straight.
Tuesday, May 28
Venus and Jupiter appear closest together during twilight this evening. The two brightest planets will look stunning with naked eyes or binoculars as Jupiter slides 1.0° south (to the lower left) of its companion. The pair won’t appear this close again until August 2014.
Wednesday, May 29
The separation of the three evening planets grows to 5° tonight, bringing to a close this year’s most spectacular series of planetary conjunctions. Venus lies directly above Jupiter and Mercury appears to Venus’ upper left. During the next few weeks, Jupiter will drop into the Sun’s glare while Mercury and Venus continue to shadow each other. The two inner planets will have another conjunction June 20.
Spiral galaxies M65 (lower right), M66 (bottom center), and NGC 3628 ar visible through large binoculars from a dark observing site. // Chuck Kimball
Thursday, May 30
You don’t need a telescope to view some attractive spring galaxies. With 10x50 binoculars in hand, scan about 3° southeast of 3rd-magnitude Theta (θ) Leonis, the star that marks the right angle corner of Leo the Lion’s hindquarters. There you’ll spy the pair of spiral galaxies cataloged as M65 and M66. Just 0.6° north of this duo lies a third spiral, NGC 3628, but you’ll need 15x70 binoculars to locate it. To learn more about this season’s binocular objects, see “Explore 11 spring binocular gems” in the May issue.
Friday, May 31
Mercury, Venus, and Jupiter, from top to bottom, spread out along a 7°-long straight line in evening twilight.
Last Quarter Moon occurs at 2:58 p.m. EDT. When it rises around 1:30 a.m. local daylight time tomorrow morning, it will appear slightly less than half-lit. Earth’s only natural satellite then appears against the background stars of western Pisces.
Ceres passes less than 1° from 4th-magnitude Iota (ι) Gem late in late May. // Astronomy: Roen Kelly
Saturday, June 1
Tonight offers a good opportunity to track down asteroid 1 Ceres. The solar system’s largest asteroid — it’s so big, in fact, that astronomers now also classify it as a “dwarf planet” — lies about 2° west of 1st-magnitude Pollux and less than 1° due north of the 4th-magnitude star Upsilon (υ) Geminorum. This region stands about 15° high in the west-northwest at the end of evening twilight. You’ll need a telescope to spot 9th-magnitude Ceres. To confirm your sighting, sketch the field and return to it a night or two later. The object that moved is the asteroid.
Sunday, June 2
Although Saturn reached opposition at the end of April, it still looks spectacular. It lies among the background stars of eastern Virgo and reaches its peak in the south around 10:30 p.m. local daylight time. The planet shines at magnitude 0.3, noticeably brighter than Virgo’s brightest star, Spica, which lies 13° west of the planet. When viewed through a telescope, Saturn’s globe measures 18" across while the rings span 42" and tilt 17° to our line of sight.