Sky at a Glance, April 25 – May 3

Friday, April 25

Bright Jupiter shines inside the big Arch of Spring, which spans the western sky at dusk. Above Jupiter, Pollux and Castor form the Arch's top (as seen from mid-northern latitudes). To their lower left is Procyon, the Arch's left end. Farther to their lower right is the other end: Menkalinen and then bright Capella.

Dawn view

The waning crescent Moon and Venus at dawn.

At dawn Saturday morning, spot the thin crescent Moon low in the east to the left of Venus, as shown here.

Saturday, April 26

Brilliant Mars, shining in the southeast after dusk, has been drawing closer to Gamma Virginis (Porrima), magnitude 2.7. Look for the little star about 2° to Mars's upper right. They'll appear closest (1.4° apart) on May 4th and 5th. Gamma Vir is a fine, tight telescopic double with a current separation of 2.1 arcseconds. Take a look at it with your scope at high power after you're done with Mars!

Sunday, April 27

To the left of Mars after dusk this week, by about three fists at arm's length, shines Arcturus in the east. High to Arcturus's upper left, you'll encounter the handle of the Big Dipper.

Monday, April 28

With the Moon out of the sky, now's a fine time to work through parts of the Virgo Galaxy Cluster with your scope. The cluster's galaxies are numerous but mostly faint, averaging 55 million light-years away, so you'll need a highly detailed, large-scale chart. To explore the northern part of the cluster (in Coma east of Denebola), use Sue French's Deep-Sky Wonders article and map, with stars to 10th magnitude, in the May Sky & Telescope, page 56.

Tuesday, April 29

New Moon (exact at 2:14 a.m. on this date EDT). A partial eclipse of the Sun occurs for Australia, and the eclipse is annular on the horizon for a bit of Antarctica. Map and details.

Crescent Moon at dusk

The thin waxing crescent returns to the evening sky, passing through Taurus.

Wednesday, April 30

Can you see the hairline Moon yet in the west in twilight? It's about a fist-width to the lower right of Aldebaran for North American skywatchers. Binoculars will help. How about the departing Pleiades?

Thursday, May 1

Look for Aldebaran now below the waxing crescent Moon in twilight. Farther to the Moon's left, Orion is sinking away.

Friday, May 2

How soon after sunset can you see the first stars and planets coming out? The brightest is Jupiter. Look for it high in the west, almost two fist-widths at arm's length above or upper left of the Moon. The second brightest is Sirius, sinking in the southwest.

Saturday, May 3

The waxing crescent Moon shines below Jupiter in the west at dusk. Above Jupiter are Pollux and Castor.


Want to become a better astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.

This is an outdoor nature hobby. 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 guide to astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).

Pocket Sky Atlas

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but it's still less than one per square degree on the sky. Also plotted are many hundreds of telescopic galaxies, star clusters, and nebulae.

Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The standards are the little Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger and deeper Sky Atlas 2000.0 (stars to magnitude 8.5); and once you know your way around, the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.

You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, the bigger Night Sky Observer's Guide by Kepple and Sanner, or the beloved if dated Burnham's Celestial Handbook.

Can a computerized telescope replace charts? Not for beginners, I don't think, and not on mounts and tripods that are less than top-quality mechanically (able to point with better than 0.2° repeatability, which means fairly heavy and expensive). As Terence Dickinson and Alan Dyer say in their invaluable 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 on April 24, 2014

On April 24th, as seen at nighttime in the Philippines, Mars was displaying a thin orographic (mountain-generated) cloud over Olympus Mons near center and bright clouds in the Chryse region near the evening limb (left; celestial west). South is up; the North Polar Cap is at bottom. The large diagonal dark region at upper right is Mare Cimmerium.
Christopher Go.

Mercury is hidden in the glare of the Sun.

Venus (magnitude –4.2) is the bright "Morning Star" low in the east during dawn. How late into the growing daylight can you follow it?

Mars shines at magnitude –1.2 high in the southeast after dark with Spica well below it, and highest in the south around 11 p.m. In a telescope, Mars is still 14.9 to 14.5 arcseconds wide. See the Mars map and observing guide in the March Sky & Telescope, page 50. Use our Mars Profiler to find which side of the planet will be facing you when you plan to observe it.

Jupiter with Red Spot and Io shadow transit

Jupiter on April 28th, imaged by Christopher Go at 10:40 UT. South here is up. The black shadow is Io's. Io itself is nearing the planet's left (celestial west) limb, on the edge of the Equatorial Zone and South Equatorial Belt. Thick white turbulence roils behind the Great Red Spot, and the Red Spot Hollow shows a gray outline, especially on its following side.

Jupiter (magnitude –2.0, in central Gemini) shines high in the southwest in twilight. It sinks westward through the evening and sets around 1 a.m. In a telescope it has shrunk to 35″ across its equator.

Saturn (magnitude +0.1, in Libra) reaches opposition next week. It now rises in twilight and stands highest in the south around 1 or 2 a.m. By then it's far left of Mars, and half as far to the upper right of Antares.

Uranus and Neptune are still low in the dawn.


Watch our SkyWeek TV short, now coming to an end!


"We may be little guys, but we don’t think small. It’s the courage of questions, of grasping our true circumstances, and not pretending we are at the center of it all, that is adulthood."
— Ann Druyan, 2014. The remade Cosmos series continues on Sunday nights. Watch online anytime.


All descriptions that relate to your horizon — 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) is Universal Time (UT, UTC, or GMT) minus 4 hours.