Sky at a Glance | June 22nd, 2012

The waxing crescent Moon guides the way to Mercury, Pollux, and Castor far to its right. (The visibility of the faint objects in bright twilight is exaggerated here,)
Alan MacRobert

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Friday, June 22

  • Spot the crescent Moon in the western twilight this evening, then look far to its right for Mercury, Pollux, and Castor as shown above. Binoculars help.

    Saturday, June 23

  • Look about a fist-width over the Moon for Regulus this evening, as shown above.

    Sunday, June 24

  • The brightest star high in the east these evenings is Vega. The brightest far to its lower right is Altair. Left or lower left of Altair, by a bit more than a fist-width at arm's length, look for the little constellation Delphinus, the leaping Dolphin. Its nose points left.

    Watch the Moon pass under Mars and the Saturn-Spica pair as it waxes from night to night.

    Monday, June 25

  • The Moon shines below distant little Mars during and after dusk.

    Tuesday, June 26

  • First-quarter Moon this evening (exact at 11:30 p.m. EDT). The Moon shines in Virgo, below the line from Saturn to Mars.

    Wednesday, June 27

  • The Moon forms a nice triangle with Saturn and Spica this evening, as shown here.

  • Latest sunset of the year (at 40° north latitude).... even though the solstice and longest day were on June 20th.

    Thursday, June 28

  • Saturn and Spica are now to the right of the waxing gibbous Moon.

    Dawn view
    Jupiter and Venus are creeping a little higher every morning.
  • Have you spotted Jupiter and Venus low in the dawn yet? They're getting higher and easier every day.

    Friday, June 29

  • Now that June is about to turn into July, the Teapot of Sagittarius is up and sitting level low in the southeast after the sky becomes fully dark.

    Saturday, June 30

  • The Moon shines in the head stars of Scorpius this evening, with Antares to its lower left.

  • Mercury is at greatest elongation, 26° east of the Sun low in evening twilight.


    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 map in the center of each issue of Sky & Telescope, the essential magazine of astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).

    Sky Atlas 2000.0 (the color Deluxe Edition is shown here) plots 81,312 stars to magnitude 8.5. That includes most of the stars that you can see in a good finderscope, and typically one or two stars that will fall within a 50× telescope's field of view wherever you point. About 2,700 deep-sky objects to hunt are plotted among the stars.
    Alan MacRobert

    Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The standards are the little Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger and deeper Sky Atlas 2000.0 (stars to magnitude 8.5); and the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts effectively.

    You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, the bigger Night Sky Observer's Guide by Kepple and Sanner, or the classic if dated Burnham's Celestial Handbook.

    Can a computerized telescope replace charts? I don't think so — not for beginners, anyway, and especially not on mounts and tripods that are less than top-quality mechanically (able to point with better than 0.2° repeatability). As Terence Dickinson and Alan Dyer say in their invaluable Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."


    This Week's Planet Roundup

    Jupiter on June 20, 2012
    Jupiter is still low in the dawn for most of us, but from his low latitude in the southern Philippines, Christopher Go is already imaging the giant planet. It was 26° up for him at the time of this image on June 20th.


    South here is up. The South Equatorial Belt above center has become relatively narrow and dark red-brown, while the North Equatorial Belt has turned wide and, in its southern two-thirds, turbulent. This is the opposite of how the two belts appeared last year! Ganymede is just off the lower right edge.

    Alan MacRobert

    Mercury (about magnitude 0.0 and fading) is low in the west-northwest about 40 to 60 minutes after sundown. Well to its right are fainter Pollux and Castor.

    Venus (magnitude –4.5) shines low in the east-northeast during dawn. Don't confuse it with Jupiter to its upper right. The two planets remain 5° or 6° apart this week, crossing the background of Aldebaran and the Hyades.

    Mars (magnitude +0.8, in Virgo) shines orange in the southwest at dusk and lower in the west later. It's still about 25° from the Saturn-and-Spica pair to its left, but it's heading their way! Mars will shoot the gap between them in mid-August.

    In a telescope Mars is gibbous and tiny (6.8 arcseconds wide), continuing to fade and shrink.

    Jupiter (magnitude –2.0) shines low at dawn, to the upper right of Venus. See Venus above.

    Saturn on June 18, 2012
    Saturn on June 18th, imaged by Christopher Go. South is up here. Note the bright, pale greenish North North Temperate Zone (NNTZ) with its slight whitish irregularities. This is the remains of the great white spot outbreak that began a year and a half ago.

    Saturn (magnitude +0.6, in Virgo) shines in the southwest as twilight fades. Below it by 5° is Spica. Later after dark they move lower to the west-southwest.

    Uranus (magnitude 5.9, at the Pisces-Cetus border) is in the east-southeast before the first light of dawn.

    Neptune (magnitude 7.9, in Aquarius) is in the south-southeast before dawn. Finder charts for Uranus and Neptune.


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


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