Sky at a Glance | June 22nd, 2007

By: Alan MacRobert June 22, 2007 0

Some daily events in the changing sky for June 22 – 30.

Don't miss the Venus-Saturn conjunction on the 30th! Mark your calendar.

Sky & Telescope diagram

Friday, June 22

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

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 9:24 p.m. Eastern Daylight Time. The Red Spot is easier to detect in a telescope this season than it has been in years; see the photo under "This Week's Planet Roundup" below. It should be about as easily visible for an hour before and after its transit times in a good 4-inch telescope, if the atmospheric seeing is sharp and steady. A light blue or green filter helps improve contrast. (For the times of all Red Spot transits, good worldwide, see June Sky & Telescope, page 58.)

Saturday, June 23

The star twinkling to the upper left of the Moon tonight is Spica. Very high above them shines brighter Arcturus.

In a telescope, Saturn's big moon Titan can be spotted three or four ring-lengths to Saturn's east this evening and tomorrow evening.

Sunday, June 24

Spica now shines to the right of the Moon.

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

Jupiter's Red Spot transits around 11:02 p.m. EDT.

Monday, June 25

After dark this week, the Big Dipper hangs by its handle nearly straight down in the northwest, while the (dim) Little Dipper floats nearly straight up from Polaris in the north.

Tuesday, June 26

Jupiter's Red Spot transits around 12:40 a.m. Wednesday morning EDT; 9:40 p.m. Tuesday evening PDT.

Wednesday, June 27

Tonight the big bright gibbous Moon hangs out with the Jupiter-Antares couple, as shown below.

Thursday, June 28

This evening the Moon is below or lower left of Jupiter and Antares, as shown below.

Friday, June 29

Jupiter's Red Spot transits around 10:09 p.m. EDT.

Saturday, June 30

Full Moon (exact at 9:49 a.m. EDT). In the time zones of Europe and Asia this is the second full Moon in the calendar month, sometimes called a "blue Moon."

This evening in twilight, Venus and Saturn appear closest together (0.7°) as seen from the Americas, as shown above. They'll fit together in the field of view of most telescope eyepieces that give a magnification of 50x or less. But how much dimmer the surface of Saturn appears than the dazzling crescent of Venus! This is because Saturn is almost 13 times farther away from the Sun — so it's lit by sunlight only 1/160 as bright.

The Moon passes Jupiter and Scorpius as it waxes toward full. (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. For clarity, the Moon is shown three times actual size.)

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 somewhat 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 hidden in the glare of the Sun.

Venus (magnitude –4.5, at the Cancer-Leo border) is the brilliant "Evening Star" in the west during twilight. Watch fainter Saturn closing in on it each day! See "Saturn" below.

Mars (magnitude +0.8, crossing from Pisces into Aries) is gradually getting higher in the eastern sky before dawn. In a telescope, it's still just a tiny blob 6 arcseconds wide.

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 p.m. daylight saving time. Antares, less bright, sparkles 6° to Jupiter's lower right. These 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 them shrinks from 6° on the 22nd to just 0.7° at their conjunction on the 30th!

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

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 in late evening (it was at opposition on June 18th). 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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