Sky at a Glance | May 4th, 2007

Some daily events in the changing sky for May 4 – 12.

Looking away from the sunrise glow befiore dawn
The Moon passes Antares and Jupiter in the morning sky as it wanes after full. (These scenes are drawn for the middle of North America. European observers: move each Moon symbol a quarter of the way toward the one for the previous date. The blue 10° scale is about the size of your fist held at arm's length. For clarity, the Moon is shown three times actual size.)
Sky & Telescope diagram.

Friday, May 4

  • The annual Eta Aquarid meteor shower peaks before dawn Saturday morning; it's observable mostly from the tropics and the Southern Hemisphere. But even there this isn't a good year for the Eta Aquarids, what with the bright moonlight.

    Saturday, May 5

  • This week, as the evening grows late, bright Vega climbs well up in the northeast. Meanwhile Arcturus is shining very high in the southeast. Look a third of the way from Vega to Arcturus for the dim Keystone of Hercules. Look two thirds of the way for the dim semicircle of Corona Borealis, the Northern Crown.

    Sunday, May 6

  • A small telescope will always show Titan, Saturn's largest moon. Tonight and tomorrow Titan is three or four ring-lengths to Saturn's east. A guide to identifying all of Saturn's satellites visible in amateur scopes is in the May Sky & Telescope, page 51.

    Monday, May 7

  • This evening, Venus passes extremely close to the 4.8-magnitude star 139 Tauri. You'll need a telescope; Venus is more than 3,000 times brighter than the star. How close they appear will depend on your location. The star will come within arcseconds of the planet's edge as seen from the western Atlantic, writes David Likuski. East Coast observers will catch them at dusk not long after. There will be no occultation, but the minimum miss distance, according to Jean Meeus, is a mere 2 arcseconds.

  • How many galaxies have you seen with binoculars? Under the handle of the Big Dipper are four you can try for using Gary Seronik's Binocular Highlight chart in the May Sky & Telescope, page 44. It's much easier to see such faint targets if you mount your binoculars or image-stabilize them; here's a cheap and easy way to do so.

    Tuesday, May 8

  • The red long-period variable stars R Corvi and RU Herculis should be at maximum light (7th or 8th magnitude) this week.

    Wednesday, May 9

  • Venus passes just north (upper right) of the star cluster M35 in the feet of Gemini. Use binoculars or a small, wide-field scope.

    Thursday, May 10

  • Last-quarter Moon (exact at 12:27 a.m. EDT on this date).

    Friday, May 11

  • The waning crescent Moon points the way to Mars low in the glow of dawn on Saturday and Sunday mornings, as shown below.

    Saturday, May 12

  • It's May, so the Big Dipper floats upside down at its highest in the north after dark. Face north and look almost straight up.

    Looking east at dawn
    If you're an early riser, you can use the Moon to find your way to an early sighting of Mars — which will blaze at opposition in the evening sky next Christmas. (These scenes are drawn for the middle of North America. European observers: move each Moon symbol a quarter of the way toward the one for the previous date.)
    Sky & Telescope diagram.

    Want to become a better amateur astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly foldout map in each issue of Sky & Telescope, the essential magazine of astronomy. Or download our free Getting Started in Astronomy booklet (which only has smaller, bimonthly maps).

    Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of maps; the standard is Sky Atlas 2000.0) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion or the enchanting though increasingly dated Burnham's Celestial Handbook). Read here how to use them most effectively.

    More beginners' tips: "How to Start Right in Astronomy".

    This Week's Planet Roundup

    Mercury is hidden, for now, in the glare of the Sun. Later in May it will leap up from the sunset for its best evening showing of the year (for skywatchers at mid-northern latitudes).

    Venus in ultraviolet, May 8, 2007
    The clouds of Venus may be featureless to the eye, but not in ultraviolet light. Here's the latest in Sean Walker's continuing series of UV Venus imagery. He took this stacked video image (false-colorized to show contrasts better) with a 12.5-inch reflector at f/40 on the evening of May 8th. Click the image for a daily animation, May 2 to 5. The cloud patterns change a lot from day to day!
    S&T: Sean Walker

    Venus (magnitude –4.2, at the Taurus-Gemini border) is the brilliant "Evening Star" in the west during and after twilight. To Venus's lower right, watch the almost-first-magnitude star Beta Tauri moving farther downward day by day.

    In a telescope Venus is nearing dichotomy (half-lit phase). Venus will probably appear exactly half-lit a week or so before it reaches its greatest elongation from the Sun on June 8th. The smallest telescope will show its changing phases.

    Mars (magnitude +1.0, crossing from Aquarius into Pisces) is still low in the east-southeast during dawn. If you turn a telescope on it, don't worry, your scope's not broken. Mars is only 5 arcseconds wide — it's supposed to be a tiny, featureless blob.

    Jupiter on May 2, 2007
    Jupiter's Great Red Spot is still quite prominent, and a white streak from its northern edge runs all the way rightward across this image — dividing the South Equatorial Belt into a dark north side and a pale south side. The South Tropical Zone and South Temperate Zone are very bright white, with the dark South Temperate Belt almost nonexistent between them. Note the unusual crisscrossing plumes and festoons in the north side of the Equatorial Zone. North is up.
    Image by Christopher Go.

    Jupiter (magnitude –2.5, in southern Ophiuchus) rises around 10 or 11 p.m. daylight saving time and dominates the south in the hours before dawn. Antares, less bright, sparkles 10° to Jupiter's right when they rise, and to its lower right by daybreak.

    Saturn (magnitude +0.4, at the Leo-Cancer border) shines high in the southwest to west during evening. Regulus, less bright at magnitude +1.4, is 12° to its left or upper left. North of Regulus is Algieba (Gamma Leonis), not much fainter — a fine telescopic double star.

    Uranus (magnitude 6, in Aquarius) is very low in the east-southeast just before dawn, upper right of Mars.

    Neptune (magnitude 8, in Capricornus) is less low in the southeast just before dawn.

    Pluto (magnitude 14, in northwestern Sagittarius) is not far from Jupiter in the south before dawn.

    All descriptions that relate to your horizon — including the words up, down, right, and left — are written for the world's midnorthern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America. Eastern Daylight Time (EDT) equals Universal Time (UT, UTC, or GMT) minus 4 hours.

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