This Week’s Sky at a Glance, May 13 – 21
The Moon passes Regulus and Jupiter on Friday and Saturday the 13th and 14th.
Friday, May 13
• As twilight fades, look upper left of the first-quarter Moon for Regulus, as shown here. Brighter Jupiter shines much farther to the Moon's left (for North America). As night grows late, this scene descend to the southwest and rotates clockwise.
• Jupiter's Great Red Spot should cross Jupiter's central meridian tonight around 12:27 a.m. EDT; 9:47 p.m. PDT. The spot is in good view for at least an hour before and after.
Saturday, May 14
• The two brightest things in the evening sky, the Moon and Jupiter, shine high just a few degrees apart this evening, as shown here. Third brightest is Mars, low in the southeast after dark.
Sunday, May 15
• Now the Moon forms a curving line with Jupiter and Regulus to its right, as shown above. Continue the line far left, and you come to Spica.
Monday, May 16
• Three zero-magnitude stars shine after dark in May: Arcturus high in the southeast, Vega lower in the northeast, and Capella in the northwest. They appear so bright because each is at least 60 times as luminous as the Sun, and because all are relatively nearby: 37, 25, and 42 light-years from us, respectively.
Brighter, however, are Jupiter and Mars, high in the southwest and low in the southeast after dark. These are 42 and 4 light-minutes from Earth tonight, respectively.
• Jupiter's Great Red Spot should transit the planet's central meridian around 9:57 p.m. EDT.
Tuesday, May 17
• Look for Spica lower left of the waxing gibbous Moon this evening (for North America). To the Moon's right or upper right is fainter Gamma Virginis (Porrima), a famous close double star for telescopes. Its nearly-equal components are currently 2.5 arcseconds apart.
Wednesday, May 18
• Spot Spica to the Moon's right at nightfall, and to its lower right as night grows late. Far to their lower left blazes Mars, shining its biggest and brightest in more than a decade as it nears opposition. Mars heads up the triangle that it forms with steady Saturn and twinkling Antares.
• Jupiter's Great Red Spot should transit the planet's central meridian around 11:36 p.m. EDT.
Thursday, May 19
• With summer still about a month away (astronomically speaking), the last star of the Summer Triangle doesn't rise above the eastern horizon until about 10 or 11 p.m. That's Altair, the Triangle's lower right corner. Its highest and brightest corner is Vega. The third is Deneb, sparkling less far to Vega's lower left.
The bright evening Moon forms very different geometrical patterns with Mars, Saturn, and Antares on Friday, Saturday, and Sunday evenings (May 20th, 21st, and 22nd).
Friday, May 20
• The nearly full Moon is low the east-southeast at sunset and shines above Mars as twilight fades. How soon can you pick out Mars? How much later will it be until you can pick out fainter Antares rising 8½° below Antares?
And what about Saturn, 7½° left of Antares? Saturn and Antares rise at the same time if you're near 35° N latitude (North Carolina, central California). If you're north of there Saturn rises first; south of there, Antares.
Saturday, May 21
• Mars is at opposition tonight. It's almost at its very closest to Earth, though not exactly so until the 30th.
• The full Moon this evening forms a rough rectangle with Mars to its right or lower right, Antares farther below it, and Saturn to its lower left, as shown here (seen from North America). Think photo opportunity.
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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.
The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but it's less than one per square degree on the sky. Also plotted are many hundreds of telescopic galaxies, star clusters, and nebulae. Shown above is the new Jumbo Edition for easier reading in the night. Click image for larger view.
Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The basic standard is the Pocket Sky Atlas (in either the original or new Jumbo Edition), which shows stars to magnitude 7.6.
Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5, nearly three times as many. The next up, once you know your way around, is 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, or the bigger Night Sky Observer's Guide by Kepple and Sanner.
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 (meaning heavy and expensive). And 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 was 14.4 arcseconds wide on April 19th when Phil Miles of Queensland, Australia, took this image with a 20-inch reflector. South is up. Dark Sinus Sabaeus and Sinus Meridiani extend in from the left (preceding). The pointy peninsula a bit farther right is the Oxia Palus region. Lower right from there are big Niliacus Lacus and Mare Acidalium. The North Polar Cap has almost shrunken away in the northern-hemisphere summer. Clouds appear in the wintry far south and especially around the morning limb.
Jupiter as imaged by S&T's Sean Walker on April 21st with a 12.5-inch scope. The Great Red Spot is vivid. Dark material lines the Red Spot Hollow like eye shadow.
Saturn's rings are wide open this season, tipped 26° to our line of sight and extending above the planet's north and south poles. Damian Peach took this image with a 14-inch Schmidt-Cass on March 19th. South is up.
Mercury and Venus are hidden in the glare of the Sun.
Mars (about magnitude –1.9, smack in the head of Scorpius) reaches opposition and closest approach to Earth on the nights of May 21st and 30th, respectively. It rises around sunset. After dark it shines in the southeast almost as bright as high Jupiter.
Look for Antares about 7° below it and Saturn 10° or 11° to its lower left during the evening. The Mars-Antares-Saturn triangle stands highest in the south around 2 a.m., now with Saturn left of Mars. By early dawn the triangle is low in the southwest.
In a telescope Mars is now about 18 arcseconds wide, nearly the 18.6 arcseconds that it will reach when closest to Earth at May's end. See our telescopic guide to Mars, with map, in the April Sky & Telescope, page 48, and set our Mars Profiler for your time and date. If you're ambitious and have a big scope, try hunting Phobos and Deimos, the two tiny Martian moons, using theJune Sky & Telescope, page 48.
Jupiter (magnitude –2.2, in southern Leo) stands high in the south in twilight, then starts declining toward the southwest. See our telescopic guide to Jupiter in the March Sky & Telescope, page 48.
Saturn (magnitude +0.1, in southern Ophiuchus over Scorpius) rises about 40 minutes after brighter Mars, following about 11° to Mars's lower left. They cross the southern sky through the night, and by dawn they're low in the southwest.
Uranus is hidden low in the glow of dawn.
Neptune (magnitude 7.9, in Aquarius) is low in the east-southeast as dawn begins.
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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.
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“This adventure is made possible by generations of searchers strictly adhering to a simple set of rules. Test ideas by experiments and observations. Build on those ideas that pass the test. Reject the ones that fail. Follow the evidence wherever it leads, and question everything. Accept these terms, and the cosmos is yours.”
— Neil deGrasse Tyson
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