Sky at a Glance | June 29th, 2012

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 nightfall.

    Saturday, June 30

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

    Dawn view
    Jupiter and Venus remain 5° apart low in the dawn all week, with the Pleiades above them and Aldebaran just below. The lineup is vertical as seen from near latitude 40° north (New York, Denver), the latitude for which these scenes are always drawn.
  • Remember when Venus and Jupiter paired up spectacularly in the evening last March? Now they're at it again, but this time low in the dawn, as shown at right. Best time: about an hour or so before your local sunrise (make sure the Daylight Saving Time box is checked if needed.)

  • A leap second will be inserted into the world's civil time systems at the end of June 30th Coordinated Universal Time (the second before 8:00 p.m. Eastern Daylight Time). The minute 23:59 UTC will have 61 seconds, not 60, to adjust for a slight accumulated slowdown in Earth's spin. The last leap second was added to the world's clocks at the end of 2008. As the moment arrives, watch your favorite online time service and see if they get it right.

    Sunday, July 1

  • As soon as the stars come out, look high in the northwest for the Big Dipper hanging straight down by its handle. As night advances, the Dipper dips lower and to the right as if to scoop up water.

    Monday, July 2

  • Vega is the brightest star very high in the east after dark. Deneb is the brightest to its lower left. Altair is farther to Vega's lower right. These three form the big Summer Triangle.

    Tuesday, July 3

  • The full Moon shines in the southeast after dark. The bright star far to its upper left is Altair. Look just above Altair, by about a finger-width at arm's length, for fainter Tarazed (Gamma Aquilae). Tarazed, an orange giant, is much more luminous than Altair but is almost 20 times farther away (330 light-years, compared to Altair's distance of 17 light-years).

    Wednesday, July 4

  • Watching fireworks this evening? As you're waiting for darkness to arrive, point out the two brightest stars of summer: Vega very high in the east, and Arcturus very high in the southwest.

    Far below Arcturus are Saturn and, just under it, Spica. Off to their right and perhaps a bit lower is orangy little Mars.

  • Earth is at aphelion, its farthest from the Sun for the year (just 1/30 farther than at perihelion in January).

    Thursday, July 5

  • The waning gibbous Moon rises around nightfall. The bright star high above it is Altair. Look a fist-width or more to Altair's left, and perhaps a bit lower, for the little constellation Delphinus, the leaping Dolphin. His nose points left.

    Friday, July 6

  • After nightfall at this time of year, the W-shaped constellation Cassiopeia has just passed its lowest point in the north and is beginning its long, slow climb in the north-northeast. The later in the night you look, the more altitude it gains. But the farther south you live, the lower it will be.

    Saturday, July 7

  • The red long-period variable star R Draconis should be at its maximum brightness of about magnitude 7.6 this week. Binoculars should show it. See the article and finder charts in the July Sky & Telescope, page 50.


    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).

    Pocket Sky Atlas
    The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but that's less than one star in an entire telescopic field of view, on average. By comparison, Sky Atlas 2000.0 plots 81,312 stars to magnitude 8.5, typically one or two stars per telescopic field. Both atlases include many hundreds of deep-sky targets — galaxies, star clusters, and nebulae — to hunt among the stars.
    Sky & Telescope

    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, pale and turbulent. This is just the opposite of how the two belts appeared last year! Ganymede is just off the lower right edge.

    Alan MacRobert

    Mercury (about magnitude +0.5 and fading) is becoming harder to see very low in the west-northwest about 45 minutes after sundown. Far to its right are fainter Pollux and Castor; use binoculars.

    Venus and Jupiter (magnitudes –4.7 and –2.1) shine low in the east-northeast during dawn. They're stacked 5° apart with Jupiter on top, as shown at the top of this page. Watch Aldebaran, much fainter, closing in on Venus from below. In Venus's starry background are the Hyades, while the Pleiades pose above Jupiter. Bring binoculars and look early!

    Mars (magnitude +0.8, in Virgo) glows orange in the west-southwest at dusk and lower in the west later. It's still about 22° from the Saturn-and-Spica pair to its left, but it's heading their way. Mars will pass right between them in mid-August.

    In a telescope Mars is gibbous and very tiny (6.6 arcseconds wide), continuing to fade and shrink.

    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 +0.7, in Virgo) shines in the southwest as twilight fades. Below it by nearly 5° is Spica. After dark they move lower to the west-southwest.

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

    Neptune (magnitude 7.9, in Aquarius) is at its highest in the south by the first light of 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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