Sky at a Glance | May 28th, 2010

By: Alan MacRobert May 28, 2010 0

By 11 p.m. on Friday the 28th, the big bright Moon is up in the southeast with Scorpius rising to its right.

Friday, May 28

The Moon, barely past full, rises in the southeast late this evening with Scorpius glittering faintly through the moonlight to its right, as shown here.

A small telescope will show Saturn's big moon Titan at greatest elongation tonight and tomorrow, about four ring-lengths to Saturn's east.

Saturday, May 29

Mars has closed to within hardly more than 4° from Regulus. Look for this color-contrast pair high in the west after dark. The star above them is Gamma Leonis.

Sunday, May 30

With summer's approach, the big Summer Triangle is making its way up in the eastern sky. Vega is the highest and brightest of the Triangle's three stars, outshining anything else in the east during evening. Deneb is the brightest star to Vega's lower left, by two or three fist-widths at arm's length. Look for Altair rising three or four fists to Vega's lower right.

Monday, May 31

The end of May finds the Big Dipper already pivoted around to hang straight down after the last trace of twilight fades out. Look for it high in the northwest.

The dim Little Dipper, meanwhile, is now standing almost vertically on its handle-end, Polaris, lower due north.

Ceres, magnitude 7.5, is dimly visible in binoculars as it passes south of the Lagoon Nebula in Sagittarius for a few nights in early June 2010. The tick marks are for 0:00 Universal Time (GMT) on the dates indicated; this is at 8 p.m. Eastern Daylight Time on the evening of the previous date.

Sky & Telescope diagram; Everton Allen photo

Tuesday, June 1

Ceres, the largest and first-discovered asteroid, is just south of the Lagoon Nebula in Sagittarius late tonight (once Sagittarius rises into good view), though light from the waning Moon will be in the sky. Use the finder chart here. The ticks on Ceres's path are for 0:00 UT on the dates indicated; this is 8 p.m. Eastern Daylight Time on the previous date. (So, for instance, late on the night of June 1 in the Americas, look for Ceres a little past the "June 2" tick.) Put a pencil dot on Ceres's track at the date and time you plan to look for it.

For more, and a chart through the end of August, see Ceres in 2010.

Wednesday, June 2

High overhead under the curve of the Big Dipper's handle is Canes Venatici, the Hunting Dogs, with several Messier galaxies that you may be able to log with binoculars. M51 is famous though difficult. To hunt out M63, M94, and M106, see Gary Seronik's Binocular Highlight column and chart in the June Sky & Telescope, page 45.

Thursday, June 3

Mars has now closed to within just 3° of Regulus, and they're almost the same brightness too. Look for this striking color-contrast pair high in the west after dark. Follow them day by day through their June 6th conjunction. The star above them or to their upper right is Gamma Leonis.

The Moon passing Jupiter in the dawn.

Sky & Telescope diagram

Friday, June 4

Last-quarter Moon (exact at 6:13 p.m. Eastern Daylight Time).

The faint comet C/2009 R1 (McNaught) is nearing its mid-June period of best visibility, low in the northeast just before the start of dawn. You'll need a telescope or (perhaps) binoculars. See our article and finder chart.

Saturday, June 5

Having a late Saturday night? The waning Moon rises in the east around 1 or 2 a.m. Sunday morning, with bright Jupiter to its lower right. They're higher by Sunday dawn, as shown here.

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 the center of 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 must have a detailed, large-scale sky atlas (set of charts). The standards are the Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger Sky Atlas 2000.0 (stars to magnitude 8.5); and the even larger and deeper Uranometria 2000.0 (stars to magnitude 9.75). And read how to use your charts effectively.

You'll also want a good deep-sky guidebook, such as Sky Atlas 2000.0 Companion by Strong and Sinnott, or the more detailed and descriptive Night Sky Observer's Guide by Kepple and Sanner or the classic if dated Burnham's Celestial Handbook.

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."

This Week's Planet Roundup

Mars and Regulus in conjunction.

Sky & Telescope diagram

Mercury (about magnitude 0) is having a poor apparition very low in the east at dawn. Scan for it with binoculars far to the lower left of bright Jupiter.

Venus (magnitude –3.9, in Gemini) is the bright Evening Star shining in the west-northwest during and after twilight. Above it are Pollux and Castor. Venus is about as high in twilight as it will get this year (for skywatchers in mid-northern latitudes). Soon it will begin its long summer sink.

In a telescope, Venus is still a small (13-arcsecond) gibbous disk. It's so dazzling, in its brilliant illumination by the Sun, that you'll have the cleanest telescopic views of it in the bright blue sky before sunset — if you can find it then.

Not until late summer will Venus assume its larger and more dramatic crescent phase.

Mars (magnitude +1.1, in Leo) glows high in the west near bluer Regulus (magnitude +1.4) to its left. Mars is closing in on Regulus every day; they pass each other on June 6th, when they'll be 0.8° apart. The star above them or to their upper right is Gamma Leonis.

In a telescope Mars is just a tiny blob, 6.0 arcseconds in diameter. Can you still make out its gibbous phase?

Jupiter's dark North Equatorial Belt is wide and massive, and its South Equatorial Belt is still nearly absent, leaving the Great Red Spot floating free in whiteness. South is up. Christopher Go in the Philippines took this image on May 20th at 20:59 UT, when the central-meridian longitude was 108° (System II). On the central meridian, he writes, "Note the dark and white ovals forming a ying-yang pattern!"

The Great Red Spot is near System II longitude 150°. Assuming it stays there, here's a list to print out of all the Great Red Spot's predicted transit times for the rest of 2010.

Christopher Go

Jupiter (magnitude –2.1, below the Circlet of Pisces) shines in the east-southeast in early dawn, climbing higher each week. Nothing else there is nearly so bright! See our article on Jupiter's disappearing South Equatorial Belt.

Saturn (magnitude +1.0, in the head of Virgo) glows high in the southwest during evening. In a telescope Saturn's rings are tilted a mere 1.7° from edge-on, their minimum tilt for the next 15 years. Note the thin black shadow-line that they cast across Saturn's globe.

Uranus (magnitude 5.9, in Pisces) is in the background of Jupiter at the crack of dawn. They close in from 1.3° apart on May 28th to 0.4° at conjunction on June 8th. In a telescope Uranus is only 3.5 arcseconds wide, compared to Jupiter's 38″.

The other side of Jupiter (CM II longitude 343°), imaged by Go on May 24th. South is up. He writes: "The SEB is still very quiet. Note the bluish festoons on the Equatorial Zone extending towards the SEB!"

Christopher Go

Neptune (magnitude 7.9, at the Aquarius-Capricornus border) is in view just before dawn well to Jupiter's west (upper right). See our finder charts for Uranus and Neptune in 2010.

Pluto (magnitude 14, in northwestern Sagittarius) is highest in the south in the early morning hours. See our Pluto finder charts for 2010.

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.

"Rational and innocent entertainment of the highest kind."
— John Mills, 19th century Scottish manufacturer and founder of Mills Observatory, on amateur astronomy.

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About Alan MacRobert

Alan M. MacRobert became an avid Sky & Telescope subscriber in 1966 at age 14, joined the editorial staff in 1982, and is now a senior contributing editor, semi-retired. He played a role in practically every part of the magazine and the company's other products for more than a generation, both on the amateur-observing side and the science-reporting side. In 1994 a book collection of his observing how-tos and telescopic sky tours was published as Star Hopping for Backyard Astronomers. He has produced This Week's Sky at a Glance online every week since 1989.