Sky at a Glance | June 7th, 2013

Jupiter is gone now, but Mercury is about at its peak altitude. The blue 10° scale is about the size of your fist held at arm's length.

Friday, June 7

  • Mercury in the twilight has reached its farthest distance above Venus, 5°. See the scene at right. They're as far apart as fainter Pollux and Castor above them, which come into view as twilight dims. 5° is about three finger-widths at arm's length (depending, of course, on the width of your fingers relative to the length of your arm!).

    Saturday, June 8

  • After dark, look southeast for orange-red Antares. It's one of the two great red supergiants of the naked-eye sky; the other is Betelgeuse in winter. Around and to the upper right of Antares are other, white stars of upper Scorpius.

  • New Moon (exact at 3:14 a.m. on this date EDT).

    Sunday, June 9

  • After sunset, look for the young crescent Moon about 6° to 8° below Venus very low in the west-northwest (at the times of twilight in North America). Binoculars will help.

    How soon after new Moon on June 8th will you spot the thin waxing crescent? Its position here is plotted for the center of North America. (The visibility of faint objects in bright twilight is exaggerated.)
    Alan MacRobert

    Monday, June 10

  • The thin crescent Moon low in twilight now forms a triangle with Venus and Mercury, as shown at right. Look above the triangle for the Pollux-and-Castor pair.

  • Meteor outburst tonight? The IAU's Central Bureau for Astronomical Telegrams sent out a notice this morning about a possible outburst late tonight of the rare Gamma Delphinid meteor shower:

    "P. Jenniskens (SETI Institute) and E. Lyytinen (Helsinki, Finland) predict a return of the 1930 Gamma Delphinids meteor shower with a peak on 2013 June 11 at about 8:28 UT [4:28 a.m. on the morning of the 11th EDT, 1:28 a.m. PDT]. The shower is expected to last only about 30 minutes."

    During the 1930 outburst, three observers in the American Meteor Society recorded 51 meteors appearing in 30 minutes through the light of the full Moon. "This account is [now] interpreted as having been caused by the dust trail of a long-period comet, which thus is an unknown potentially hazardous comet that passed close to Earth's orbit in the previous return.... If so, that stream of dust is predicted to move into Earth's path in 2013 — if the radiant position of the meteors was correctly recorded in 1930."

    Tuesday, June 11

  • The waxing Moon after sunset now forms a wide arc with Castor, Pollux, and low Procyon, as shown at right. Venus and Mercury are not far from the center of the arc's curve.

  • Early Wednesday morning, the faint asteroid 332 Siri will will occult (hide) a 6.4-magnitude star east of Antares for up to 4 seconds as seen along a track from Oklahoma across northwest Texas, southern New Mexico, and southern Arizona. The star is an unusually bright one to be occulted by an asteroid, but the event happens low in the southwestern sky. See Steve Preston's maps and details about this event.

    Venus and fading Mercury are drawing closer....
    Venus and fading Mercury are drawing closer together.

    Wednesday, June 12

  • The interesting binocular field around Antares holds the dim glow of the globular cluster M4, as many skywatchers well know. But do you also know about Rho Ophiuchi, the fine binocular triple star in the same field? It's the top of a loop of five stars including Antares, as shown in Gary Seronik's Binocular Highlight column in the June Sky & Telescope, page 45.

    Thursday, June 13

  • Look above the Moon after nightfall to spot Regulus and the Sickle of Leo.

    Friday, June 14

  • The widening Moon is now lower left of Regulus and the Sickle of Leo.

    Saturday, June 15

  • Mercury is drawing closer to Venus in the twilight, as shown above. They're 3.3° apart now and will be 2° from each other at their closest on the 19th. But Mercury is fading fast.


    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.

    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

    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 guide to astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).

    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 with a telescope.

    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 beloved if dated Burnham's Celestial Handbook.


    This Week's Planet Roundup

    Mercury and Venus remain in twilight view low in the west-northwest, but Mercury is fading: from magnitude +0.2 to +0.8 from June 7th to 14th. Mercury is upper left of much brighter Venus, magnitude –3.8. Their separation closes from 5° to 3.6° during this time. Above them shine fainter Castor and Pollux.

    Venus and Mercury just ended a threesome dance with Jupiter; here's Fred Espenak's gallery of pics.

    Mars and Jupiter are hidden in the glare of the Sun.

    Saturn (magnitude +0.4, in Libra) glows in the south during evening, with Spica 12° to its right. Look almost as far to Saturn's left or lower left for Alpha Librae.

    In a telescope, Saturn's rings are tilted 17° from our line of sight. See our guide "Scrutinizing Saturn" in the May Sky & Telescope, page 50, or the shorter version on our website. And identify Saturn's many moons at any time and date with our SaturnMoons utility or handier app.

    Uranus (magnitude 5.9, in Pisces) is low in the east just before the beginning of dawn.

    Neptune (magnitude 7.9, in Aquarius) is in the southeast before dawn begins. 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.


    Like This Week's Sky at a Glance? Watch our SkyWeek TV short, also playing on PBS.


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