Sky at a Glance | June 1st, 2007

Some daily events in the changing sky for June 1 – 9.

Looking west-northwest in evening twilight
The two innermost planets still shine after sunset, though Mercury is fading now. Watch both move rapidly from day to day.
Sky & Telescope diagram

Friday, June 1

  • Mercury is at greatest elongation, 23° east of the Sun in evening twilight as shown here. See also "This Week's Planet Roundup" below.

    Saturday, June 2

  • This evening, Venus is just about perfectly lined up with Pollux and Castor to its right.

    Sunday, June 3

  • Venus and Jupiter are certainly the brightest planets — but do you know the brightest stars after dark at this time of year? They're Vega in the eastern sky, Arcturus nearly overhead toward the south, and Capella sinking very low in the northwest, far right of dimmer Mercury. All are magnitude 0. (Descriptions are for skywatchers at north temperate latitudes.)

    Monday, June 4

  • Once you recognize Vega and Arcturus, you can look for the dim Keystone of Hercules a third of the way from Vega to Arcturus, and mostly-dim Corona Borealis, the Northern Crown, two thirds of the way along.

    Tuesday, June 5

  • Jupiter is at opposition, opposite the Sun in our sky. So it rises at sunset, is highest in the middle of the night, and sets at sunrise. This is also just about when Jupiter is closest to Earth.

  • 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 10:20 p.m. Eastern Daylight Time. 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.)

  • Mars is at perihelion: closest to the Sun in its orbit.

    Wednesday, June 6

  • The asteroid 4 Vesta is still shining at a remarkably bright magnitude 5.5, not far from Jupiter. It should be distinctly visible to the unaided eye in a dark sky now that the bright Moon is gone from the evening. See the article and finder chart in the June Sky & Telescope, page 57, or the shorter version online. (On the chart, the tick marks on Vesta's path are for 0:00 Universal Time, which in the time zones of the Americas falls on the evening of the previous date.)

    Thursday, June 7

  • Jupiter's Red Spot should transit at around 11:58 p.m. EDT.

    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 on 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.

    Saturday, June 9

  • Jupiter's Red Spot should transit at around 1:36 a.m. Sunday morning EDT; 10:36 p.m. Saturday evening PDT.

  • During early dawn Sunday morning the waning crescent Moon shows the way to Mars, as illustrated here.

    Looking east at the break of dawn
    Early risers can see the waning crescent Moon pass little Mars. (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.)
    Sky & Telescope diagram.

    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 (in the feet of Gemini) remains relatively high in evening twilight, but it's fading — from magnitude +0.4 on June 1st to +1.2 on June 9th. Look for it far to the lower right of Venus, as shown at the top of this page.

    Venus (magnitude –4.4, crossing from Gemini into Cancer) is the brilliant "Evening Star" in the west during and after twilight. After standing high in twilight all spring, Venus is getting a little lower again. Pollux and Castor, much fainter, are lined up to its right early in the week. They slide away to the lower right thereafter. A telescope shows that Venus is now half-lit.

    Mars (magnitude +0.8, in Pisces) is gradually getting higher in the east before and during dawn. It's the orange-yellow dot below the Great Square of Pegasus. In a telescope, Mars is still a minuscule 6 arcseconds wide.

    Jupiter outbreak, June 1, 2007
    A weird outbreak has just erupted in Jupiter's South Equatorial Belt. It's on the central meridian just below center in this image taken by master planetary photographer Christopher Go on June 1, 2007, at 14:55 Universal Time. The almost vertical little dark wisps are quite un-Jupiterlike. Elsewhere, the Great Red Spot is just about to rotate out of sight around the planet's right-hand limb (celestial west; following). The white Red Spot Hollow around it helps make it more distinct in a telescope this season than it has been for years. North is up.

    Jupiter (magnitude –2.6, in southern Ophiuchus) is at opposition on June 5th. It glares low in the east-southeast at dusk and dominates the south by 1 a.m. daylight saving time. Antares, less bright, sparkles 7° to its right in early evening, and to its lower right later.

    Saturn (magnitude +0.5, in Leo) shines in the west during evening, upper left of dazzling Venus (by 23° to 16° this week). Watch these two closing in on each other, heading for a close conjunction at the end of June.

    Regulus, less bright at magnitude +1.4, is 10° 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 6, in Aquarius) and Neptune (magnitude 8, in Capricornus) are well up in the east-southeast before the first light of dawn.

    Pluto (magnitude 14, in northwestern 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 .