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This Week's Sky at a Glance

by Alan M. MacRobert

Some daily events in the changing sky for March 28 – April 5.

Space Station flyovers. Every evening you can see satellites creeping across the stars. The biggest one, the International Space Station, blazes as bright as Jupiter or Venus. To see when and where to look for it, put your location and time zone into our Satellite Tracker. Also given are predictions for the Hubble Space Telescope and any space shuttle in orbit.

#checkImageURL( ) Looking south-southeast in early dawn
Watch the waning Moon skim under Jupiter from one morning to the next. This scene is 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.
Friday, March 28

  • Telescope users in westernmost Europe can watch two tiny black shadows of Jupiter's moons simultaneously crossing Jupiter's face before dawn Saturday morning. Ganymede's shadow begins transiting Jupiter at 2:59 Universal Time (UT or GMT), followed by Io's shadow at 4:22 UT. Ganymede's shadow departs Jupiter's other edge at 5:57 UT, followed by Io's at 6:36 UT.

    Saturday, March 29

  • Last-quarter Moon (exact at 5:47 p.m. Eastern Daylight Time).

  • Tonight and tomorrow, Mars shines within 0.3° of 3rd-magnitude Epsilon Geminorum (a star that Mars spectacularly occulted 32 years ago!). Binoculars show beautifully the colors of golden Mars and paler yellow Epsilon Gem.

  • Saturn's biggest moon, Titan — always visible in a small-to-medium telescope — poses four ring-lengths to Saturn's west tonight.

    Sunday, March 30

  • Mars, in Gemini, is at eastern quadrature: 90° east of the Sun. This is around the time it shows its most pronounced gibbous phase.

  • Early risers Monday morning will find Jupiter shining to the upper right of the waning Moon in early dawn, as shown above. They'll be separated by about a fist-width at arm's length, depending on your location (and the size of your fist).

  • Turn a telescope on Jupiter while the sky is still fairly dark Monday morning, and you'll see the star 50 Sagittarii masquerading as a misaligned Jovian satellite, 9 arcminutes north of the planet.

    Monday, March 31

  • The red long-period variable star S Ursae Majoris, just off the Big Dipper, should be getting close to maximum light (7th or 8th magnitude), predicted for about April 14th. Use binoculars with the comparison-star chart in the April Sky & Telescope, page 70.

    Tuesday, April 1

  • Betelgeuse, the topmost bright star of Orion in the southwest after dusk, is about the same color as Mars, glowing above it by about two fist-widths at arm's length or a little more. Compare their colors. Which seems to have the deeper tint?

    Wednesday, April 2

  • Below Betelgeuse by one fist-width is Orion's horizontal Belt, and below that shines Rigel. Many sky guides call Rigel "blue-white," by contrast to orange-red Betelgeuse, but look carefully. Do you see any blue in Rigel at all?

    Thursday, April 3

  • Before sunrise Friday morning, a very thin waning crescent Moon appears upper right of Venus. Using binoculars, look for them just above the east horizon in bright twilight, about 20 minutes before sunrise. Please send us your observations! See article.

    Find your local sunrise time by checking that your location and time zone are set in our online almanac. If you're on daylight saving time like most of North America, make sure the Daylight Saving Time box is checked.

    Friday, April 4

  • It's getting to be Big Dipper season for real; the Dipper is high overhead toward the northeast these evenings. And it's got galaxies scattered all around it. See the guide to finding the pair above the Great Bear's back in the April Sky & Telescope, page 51, and others among the Bear's feet on page 73.

    Saturday, April 5

  • New Moon (exact at 11:55 p.m. Eastern Daylight Time).


    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 standards are Sky Atlas 2000.0 or the smaller Pocket Sky Atlas) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion by Strong and Sinnott, the even more detailed Night Sky Observer's Guide by Kepple and Sanner, or the enchanting though increasingly dated Burnham's Celestial Handbook). Read how to use them effectively.

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



    This Week's Planet Roundup

    Mercury and Venus are buried deep in the glare of sunrise (but see April 3 above).

    Mars (magnitude +0.8, in Gemini) shines in the southwest to west during evening, high over Orion. In a telescope Mars is just 7.0 arcseconds wide now — a tiny blob. A telescope will show, however, that Mars is gibbous.

    Jupiter (magnitude –2.2, in eastern Sagittarius) glares in the southeast before and during dawn. The farther south you live, the higher you'll be able to observe it before dawn gets too bright.

    Saturn (magnitude +0.4, near Regulus in Leo) glows high in the southeast to south during evening. Fainter Regulus (magnitude +1.4) is now just 3° from Saturn: to its right in early evening, and lower right of it later at night. Watch Saturn and Regulus draw even closer together in the coming weeks.

    The two form a narrow triangle with Gamma (γ) Leonis, only a little dimmer than Regulus at magnitude +2.1, located 8° to Saturn's north.

    Telescope users: there's more to see on Saturn than you may realize. See our Saturn observing guide in the April Sky & Telescope, page 66.

    Uranus and Neptune are still low in the glow of dawn.

    Pluto (magnitude 14.0, in northwestern Sagittarius) is well up in the south-southeast before dawn's first light.

    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 (UT, UTC, or GMT) minus 4 hours.

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