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This Week's Sky at a Glance

by Alan M. MacRobert

Some daily events in the changing sky for June 5 – 13.

Friday, June 5

  • Vega is the brightest star shining in the east after dark. Deneb is the brightest to its lower left (by two or three fist-widths at arm's length). Look for Altair farther down to Vega's lower right. These three stars form the huge Summer Triangle.

    Saturday, June 6

  • Antares Occultation. The practically full Moon occults (covers) 1st-magnitude Antares tonight for much of North America and for all of Mexico, Central America, northern South America, and the Caribbean. With the Moon this bright, you'll need a telescope. See the article and maps in the June Sky & Telescope, page 52. Local timetables.

    Sunday, June 7

  • Full Moon (exact at 2:12 p.m. Eastern Daylight Time).

    Monday, June 8

  • Early Tuesday morning, Jupiter's moons Io and Ganymede are both casting their tiny black shadows onto the planet from 1:06 to 3:16 a.m. PDT (4:06 to 6:16 a.m. EDT).

    Tuesday, June 9

  • After dark, the head of Scorpius is already looming well up in the southeast. In the depths above it smoulders the 18th-magnitude recurrent nova U Scorpii. Bradley Schaefer predicts that U Sco is likely to erupt again (to 8th or 9th magnitude) sometime this year. To catch it during its 5-hour rise, a lot of telescope users will have to be checking it often. Want to join them? See our article. Observers are especially needed at longitudes around the world that are sparsely populated with astronomers.

    Wednesday, June 10

  • In binoculars, a globular cluster looks like a dim, slightly fuzzy star. The globular M3 in Bootes offers a fine chance to make this comparison; it's just ½° from a star of the same brightness (6th magnitude). Find them starting from Arcturus, using the chart in Gary Seronik's "Binocular Highlight" in the June Sky & Telescope, page 45.

    Thursday, June 11

  • A small telescope will always show Titan, Saturn's largest moon. Tonight Titan is four ring-lengths to Saturn's east. A guide to identifying other Saturnian satellites often visible in amateur scopes is in the June Sky & Telescope, page 47.

    Friday, June 12

  • After midnight tonight, look lower left of the waning Moon in the east for Jupiter on the rise, as shown above. They stand high in the southeast by dawn.

    Saturday, June 13

  • As twilight fades this week, look low in the northwest for bright Capella. See how it twinkles at this low altitude! Binoculars may show it flashing vivid colors as it very slowly sinks.

    How late in the season can you continue to see Capella? This depends entirely on your latitude. North of latitude 46° (Seattle, Quebec City, central France) the star is circumpolar and never sets at all.




    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 each issue of Sky & Telescope, the essential magazine of 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 Sky Atlas 2000.0 or the smaller Pocket Sky Atlas) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion by Strong and Sinnott, the more detailed and descriptive Night Sky Observer's Guide by Kepple and Sanner, or the classic Burnham's Celestial Handbook). Read how to use them effectively.

    Can a computerized telescope take their place? I don't think so — not for beginners, anyway, and especially not on mounts that are less than top-quality mechanically. As Terence Dickinson and Alan Dyer say in their 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 and a curious mind." Without these, they note, "the sky never becomes a friendly place."

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




    This Week's Planet Roundup

    Mercury is both faint and buried deep in the glow of sunrise, very far lower left of Venus. Good luck.

    Venus (magnitude –4.4, near the Pisces-Aries border) shines brightly due east during dawn. In a telescope Venus appears about half lit. It's at western elongation from the Sun on June 5th (46° from the Sun), but it generally appears exactly half lit (at dichotomy) several days before. The best telescopic views of Venus come in full early-morning daylight, when the planet is higher in steadier air.

    Mars (magnitude +1.1, in Aries) has closed to within only about 4° to Venus's left. But it's 160 times fainter! There are four reasons for this: Mars is farther from the Sun so it gets illuminated less brightly, it's a smaller planet than Venus, its surface is darker than Venus's white clouds, and it's currently farther from Earth.

    Jupiter (magnitude –2.5, in Capricornus) shines brightly in the southeast before and during dawn, high enough now for good telescopic observing. The sharpest glimpses may come during morning twilight, when the atmospheric seeing sometimes turns very steady.

    Saturn (magnitude +0.9, in Leo) is now in the southwest at dusk. It moves lower to the west later in the evening. Regulus, not quite as bright, sparkles 15° to its lower right.

    In a telescope Saturn's rings appear only 4° from edge on. And see how they've dimmed! The caption at right tells why.

    Uranus (magnitude 5.9, in Pisces) is between Venus and Jupiter before dawn.

    Neptune (magnitude 7.9, in Capricornus) still appears less than 1° from Jupiter, though it's 15,000 times dimmer. See our finder charts for Uranus and Neptune.

    Pluto (14th magnitude, in northwestern Sagittarius) is highest in the south around 1 or 2 a.m. See the finder chart in the June Sky & Telescope, page 53.

    All descriptions that relate to your horizon or zenith — 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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