This Week’s Sky at a Glance

Friday, June 15

  • With summer beginning in just five days, Scorpius is already rearing up in the southeast at nightfall. Its brightest star is orange Antares. The "outrigger" stars of Antares are just below and upper right of it. Farther upper right is the row of stars marking Scorpius's head. This is a grand area to explore with a sky atlas and binoculars.

    Early risers can watch the waning Moon march toward Jupiter and Venus, which are emerging this week from the sunrise glow. (The visibility of the dim objects in bright dawn is exaggerated here. For clarity, the Moon is shown three times its actual apparent size.)
  • As dawn brightens Saturday morning, the Moon, Jupiter, and Venus form a diagonal line above where the Sun will rise, as shown here.

    Saturday, June 16

  • If you're awake in early dawn Sunday morning, look low in the east-northeast for the thin waning crescent Moon close to Jupiter, as shown here. As dawn brightens look for Venus 9° to Jupiter's lower left. Bring binoculars.

    Sunday, June 17

  • Can you see the big Coma Berenices star cluster? Does your light pollution really hide it, or do you just not know exactly where to look? The cluster is 2/5 of the way from Denebola (Leo's tail) to the end of the Big Dipper's handle (Ursa Major's tail). The cluster is about 5° wide — a big, dim glow in at least a moderately dark sky. Its brightest members form an inverted Y that nearly fills a binocular view.

    Monday, June 18

  • Vega is the brightest star on the eastern side of the evening sky. Deneb is the brightest to its lower left. Altair is farther to Vega's lower right. These form the big Summer Triangle.

  • This season there's another, temporary "Summer Triangle" toward the southwest: bright Arcturus high on top, the Saturn-Spica pair below it, and Mars off to the pair's right or lower right.

    Tuesday, June 19

  • This is the time of year when the Little Dipper floats straight upward from Polaris after dark — like a helium balloon (I sometimes think) escaped from a summer evening graduation party.

  • New Moon (exact at 11:02 a.m. EDT).

    Wednesday, June 20

  • This is the longest day and shortest night of the year in the Northern Hemisphere. Summer begins at the solstice: 7:09 p.m. EDT. This is when the Sun reaches its northernmost point in the sky and begins its six-month return southward. In the Southern Hemisphere, winter begins.

    If you have a good view of the west-northwest horizon (from mid-northern latitudes), mark precisely where the Sun sets. In a few days you should be able to detect that it's again starting to set a little south of this point. Build your own Stonehenge?

    Thursday, June 21

  • As the glow of sunset fades, look low in the west-northwest for a ragged line of the thin crescent Moon, Mercury, Pollux, and Castor, as shown below.

    When the Moon returns to evening view as a waxing crescent, use it to find your way to Mercury and departing springtime stars.

    .

    Friday, June 22

  • Spot the crescent Moon in the western twilight this evening, and 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.


    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).

    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

    Mercury (about magnitude –0.3 and fading) is very low in the west-northwest about 30 or 40 minutes after sundown. Don't confuse it with Capella far to its right, in the northwest. Pollux and Castor are above Mercury early in the week, and to the right of it by June 23rd.

    Every morning, Jupiter and Venus are getting higher and easier in the dawn.

    Venus (magnitude –4.3), after transiting the Sun on June 5th, is now deep in the glow of dawn. Look for it low in the east-northeast before sunrise. Don't confuse Venus with Jupiter to its upper right. The two planets are 9° apart on the morning of June 16th and 6° apart on June 23rd.

    Below or lower right of Venus twinkles much fainter Aldebaran; use binoculars as daybreak brightens. Jupiter and Venus, the two brightest planets, are on their way up for a grand showing in the morning sky this summer.

    Mars (magnitude +0.7, crossing from Leo into Virgo) shines orange in the southwest at dusk and lower in the west as evening grows late. This week Mars creeps to the halfway point from Regulus (off to its lower right) to the Saturn-and-Spica pair (left). Mars will shoot the gap between Saturn and Spica in mid-August.

    In a telescope Mars is gibbous and tiny (7 arcseconds wide), continuing to fade and shrink.

    Jupiter (magnitude –2.0) is coming into view deep in the glow of dawn. See Venus above.

    Saturn on June 11th. South is up. Imager Christopher Go writes, "The North North Temperate Zone (NNTZ) is very bright green" in this exaggerated-color image. "Note the bright white spot on the NNTZ" near the central meridian "and the dark barge right next to this white spot." The System III longitude of Saturn's central meridian was 181°; System II, 329°.

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

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

    Neptune (magnitude 7.9, in Aquarius) is very well up 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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