Some daily events in the changing sky for June 15 – 23.

Looking west at dusk

Watch the Moon 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 15

  • Venus and Saturn shine near each other in the west as inviting telescopic attractions at nightfall this month. Venus is turning into a thick crescent. Dimmer Saturn is getting far into the distance, but a 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 visible in amateur telescopes is in the June Sky & Telescope, page 51.)

  • Jupiter, meanwhile, draws the eye in the southeast. 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 8:38 p.m. Eastern Daylight Time. The "red" spot is more easily visible in a telescope (given good atmospheric seeing) than it has been in years; see the photo in "This Week's Planet Roundup" below. A light blue or green filter improves contrast on Jupiter a bit. For the times of all Red Spot transits this month, visible worldwide, see the June Sky & Telescope, page 58.

    Saturday, June 16

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

    Sunday, June 17

  • Vesta, the brightest asteroid, is still shining at magnitude 5.7 north of Jupiter and the head of Scorpius. This is just about your last chance to try for Vesta with your unaided eyes before moonlight starts filling the sky again. Use the finder chart in the June Sky & Telescope, page 57.

  • Jupiter's Red Spot transits around 10:16 p.m. EDT.

    Monday, June 18

  • The thin waxing crescent Moon occults Venus today in daylight for northeasternmost North America and most of Europe. The occultation happens spectacularly in twilight for parts of the Middle East, and after dark for Pakistan and India. See our article and map.

  • Everywhere else worldwide, the Moon shines near Venus low in the west in twilight. In North America, the Moon in twilight poses between Venus and Saturn, as shown above.

  • Jupiter's moon Io reappears from eclipse out of Jupiter's shadow around 1:00 a.m. Wednesday morning EDT, 10:00 p.m. Tuesday evening PDT. A small telescope will show it gradually swelling into view barely off the planet's eastern limb. (For a listing of all events among Jupiter's moons this month, visible worldwide, see the June Sky & Telescope, page 52.)

    Tuesday, June 19

  • The Moon occults Regulus in daylight for western and central North America. For much of the South, the occultation happens around sunset or in twilight. See our article and maps.

  • Jupiter's Red Spot transits around 11:54 p.m. EDT.

    Wednesday, June 20

  • With summer about to arrive, the two brightest summer stars are shining high and proud. Look for icy-white Vega high in the eastern sky just after dark, and pale yellow-orange Arcturus even higher in the southwest.

    Thursday, June 21

  • The June solstice occurs at 2:06 p.m. EDT. This is when the Sun is farthest north for the year in Earth's sky and begins its six-month return southward. Summer begins in the Northern Hemisphere, winter in the Southern Hemisphere.

  • Jupiter's Red Spot transits around 1:32 a.m. Friday morning EDT, 10:32 p.m. Thursday evening PDT.

    Friday, June 22

  • First-quarter Moon (exact at 9:15 a.m. EDT).

  • Jupiter's Red Spot transits around 9:24 p.m. EDT.

    Saturday, June 23

  • The red long-period variable star RS Scorpii should be at maximum brightness (7th magnitude) this week.

    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

    Mercury is lost in the sunset.

    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 closing in on it.

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

    Jupiter on the night of June 14–15, 2007

    Jupiter's Great Red Spot stands in striking contrast to its white surroundings this observing season. Sky & Telescope's Sean Walker shot this stacked-video-frame image from his home in New Hampshire around midnight EDT on the night of June 14–15, using a 12.5-inch Newtonian reflector at about f/40. The seeing was excellent despite Jupiter's rather low altitude in the sky as seen from his latitude of 43° north.

    S&T: Sean Walker


    Jupiter (magnitude –2.5, in southern Ophiuchus) was at opposition on June 5th. It glares in the southeast at dusk and dominates the south by 11 or midnight daylight saving time. Antares, less bright, sparkles 6° to Jupiter's lower right. The two will be evening companions all summer.

    Saturn (magnitude +0.6, in Leo) is in the west during evening, closing in on dazzling Venus from the upper left. The gap between the two shrinks from 11° to just 5° 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 8° or 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 double star.

    Uranus (magnitude 5.8, in Aquarius) and Neptune (magnitude 7.9, in Capricornus) are well up in the southeast and south, respectively, 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.

    To always get the up-to-date Sky at a Glance, bookmark this URL:
    http://SkyTonight.com/observing/ataglance .

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