Some daily events in the changing sky for June 8 – 16.

Looking west at dusk

Late this week the Moon will return to the evening sky, soon to wax its way up past Venus, Saturn, and Regulus in nightly succession. (These scenes are drawn for the middle of North America. European observers: move each Moon symbol a quarter of the way toward the one for the previous date. The blue 10° scale is about the size of your fist held at arm's length. For clarity, the Moon is shown three times actual size.)

Sky & Telescope diagram

Friday, June 8

  • Last-quarter Moon (exact at 7:43 a.m. EDT).

  • Venus is at greatest elongation, 45° east of the Sun in the twilight sky.

  • Early Saturday morning for western North America, two of Jupiter's moons (Io and Ganymede) cast their tiny shadows onto the planet's face at once: from 2:17 to 3:03 a.m. Pacific Daylight Time. This will be an interesting time to observe Jupiter with a telescope. Ganymede's shadow (like Ganymede itself) is distinctly larger than Io's.

    Saturday, June 9

  • Jupiter's Great Red Spot should cross Jupiter's central meridian (the imaginary line down the center of the planet's disk from pole to pole) around 1:40 a.m. Sunday morning EDT; 10:40 p.m. Saturday evening PDT. It should be visible for at least 50 minutes before and after in a good 4-inch telescope if the atmospheric seeing is sharp and steady. A light blue or green filter helps. (For the times of all Red Spot transits this month, visible worldwide, see the June Sky & Telescope, page 58.)

  • Early Sunday and Monday mornings the waning crescent Moon passes Mars.

    Sunday, June 10

  • Jupiter's Moon Io crosses onto Jupiter's face at 11:38 p.m. Eastern Daylight Time, followed by its tiny black shadow 7 minutes later. Io leaves Jupiter's face at 1:49 a.m. Monday morning EDT, followed by its shadow 8 minutes later.

    Monday, June 11

  • Jupiter's moon Io reappears out of eclipse by Jupiter's shadow around 11:06 p.m. EDT. A telescope will show it gradually swelling into view barely beyond Jupiter's eastern limb. Use fairly high power to help separate it from Jupiter's glare.

    A list of all the interesting phenomena of Jupiter's moons and their shadows during June, good worldwide, is in the June Sky & Telescope, page 52.

    Tuesday, June 12

  • Vesta, the brightest asteroid, is still shining at magnitude 5.6 north of the head of Scorpius. Now that the sky is dark with the Moon out of the way, have you tried looking for Vesta with your naked eyes? In any case, binoculars will show it very easily. Use the finder chart in the June Sky & Telescope, page 57.

  • Jupiter's Red Spot should transit at around 10:39 p.m. EDT.

    Wednesday, June 13

  • These moonless evenings are a perfect time to explore your way through the galaxies grouped in the feet of Virgo. See Sue French's Deep-Sky Wonders column and finder chart in the June Sky & Telescope, page 61.

    Thursday, June 14

  • New Moon (exact at 11:13 p.m. EDT).

  • Jupiter's Red Spot should transit at around 12:17 a.m. Friday morning EDT; 9:17 p.m. Thursday evening PDT.

    Friday, June 15

  • A small telescope will always show Titan, Saturn's largest moon. This evening and tomorrow evening Titan is three or four ring-lengths to Saturn's west. A guide to identifying all of Saturn's satellites that are visible in amateur telescopes is in the June Sky & Telescope, page 51.

    Saturday, June 16

  • The red long-period variable star S Herculis should be at its peak brightness (7th or 8th magnitude) this week.

  • As evening twilight fades, look very low in the west-northwest for the thin waxing crescent Moon. Above it are Pollux and Castor, as shown at the top of this page.

    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 foldout 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 maps; the standard is Sky Atlas 2000.0) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion or the enchanting though dated Burnham's Celestial Handbook). Read here how to use them most effectively.

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

    This Week's Planet Roundup

    Sunspot group 960 seen in H-alpha light, June 10

    Two small sunspots mark a big active region as revealed in this closeup of the Sun's surface taken in hydrogen-alpha light.

    S&T: Sean Walker

    The Sun is displaying an interesting magnetic active region. Sky & Telescope's Sean Walker took this image of it in hydrogen-alpha light early on Sunday morning, June 10th, using a hydrogen-alpha Personal Solar Telescope souped up with a 4-inch f/15 lens. In white light (that is, seen through an ordinary safe solar filter), only the two tiny sunspots are visible. As of Monday the 11th they're nearing the Sun's western limb. They will rotate around the limb out of sight in a couple more days. North is up, and celestial east is left.

    You can check the appearance of the Sun's spotted face every day through the eyes of the SOHO Observatory.

    Mercury (in the feet of Gemini) is dropping down into the glow of sunset and also fading fast. It's down to magnitude 1.5 on the 11th and 2.6 on the 16th. Look for it early in the week, far to the lower right of Venus in early twilight. Bring binoculars.

    Venus (magnitude –4.5, in Cancer) is the brilliant "Evening Star" in the west during and after twilight. After standing high in the dusk all spring, Venus is getting a little lower. To its upper left, Saturn and Regulus are perfectly lined up with it, as shown at the top of this page.

    In a telescope, Venus should be just beginning to show a slightly concave terminator, after appearing exactly half-lit last week.

    Mars (magnitude +0.8, in Pisces) is gradually getting higher in the east before and during dawn. It's the orange-yellow dot far below the Great Square of Pegasus.

    Mars is on its way to a Christmas-season opposition and closest approach to Earth. However, unlike during its past few oppositions, Mars this year will grow to an apparent diameter of only 16 arcseconds.

    Jupiter on June 5, 2007

    Jupiter's Great Red Spot is rotating into view around Jupiter's celestial east (following) limb in this June 5th image by Christopher Go. Note the very dark red dot, tiny but persistent, to the Great Red Spot's right in the south component of the now-divided South Equatorial Belt. Large white ovals populate the latitude of the South South Temperate Belt. The festoon activity in the Equatorial Zone continues to show weird variety. North is up.

    Christopher Go

    Jupiter (magnitude –2.6, in southern Ophiuchus) was at opposition on June 5th. It glares low in the east-southeast at dusk and dominates the south by about midnight daylight saving time. Antares, less bright, sparkles 7° to Jupiter's right in early evening, and to its lower right later in the night.

    Saturn (magnitude +0.5, in Leo) shines in the west during evening, closing in on dazzling Venus from the upper left. The gap between the two shrinks from 17° to 10° this week. Venus and Saturn are on their way to a close conjunction at the end of June.

    Regulus, less bright at magnitude +1.4, is 9° to Saturn's upper left. And look north (upper right) of Regulus by 8° for the 2nd-magnitude star Algieba (Gamma Leonis), a fine telescopic binary.

    Uranus (magnitude 5.8, in Aquarius) and Neptune (magnitude 7.9, in Capricornus) are well up in the southeast before the first light of dawn.

    Pluto (magnitude 13.9, in the northwestern corner of Sagittarius) is not far from Jupiter in the south late at night. Finder charts for Uranus, Neptune, and Pluto are in the July Sky & Telescope, page 60.

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

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