Friday, May 6
• Double shadow transit on Jupiter. Both Callisto and Io cast their tiny black shadows onto Jupiter's sunlit face from 12:38 to 1:42 a.m. EDT tonight (9:38 to 10:42 p.m. PDT).
• New Moon (exact at 3:30 p.m. EDT; 12:30 p.m. PDT).
Saturday, May 7
• Twenty or thirty minutes after sunset, try to catch the hairline crescent Moon just a few degrees above the west-northwest horizon, as shown here. Binoculars will help! Is this the youngest Moon you've ever seen? It's only about 28 hours from new as seen from the East Coast, 31 hours from new as seen from the Pacific time zone. (Calculate its age at the time of your sighting from the time of yesterday's new Moon, above.)
Aldebaran is a few degrees above or upper left of the delicate Moon. Which of the two is less difficult to see in binoculars? With the unaided eye?
Sunday, May 8
• The waxing crescent Moon hangs rather low in the west at dusk. Look left of it for orange Betelgeuse and lower right of it by a similar distance (from North America) for orange Aldebaran, as shown above.
Monday, May 9
• Mercury crosses the face of the Sun today for users of safely filtered telescopes across most of the inhabited world. See Get Ready for May 9th’s Transit of Mercury and May 9th Transit of Mercury: Everything You Need to Know.
And watch our livestream from 7:00 a.m. to 3:00 p.m. EDT.
• At dusk, the thickening Moon shines near Gamma Geminorum, the brightest star in the four feet of Gemini, as shown at top. Look below the star and Moon for Betelgeuse, the last of Orion's bright stars to sink away as winter recedes into the past.
Tuesday, May 10
• Three zero-magnitude stars shine after dark in May: Arcturus high in the southeast, Vega much 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 they're all relatively nearby: 37, 25, and 42 light-years from us, respectively.
Brighter, however, are the very different objects Jupiter and Mars, high in the southwest and low in the southeast. They're 41 and 5 light-minutes from Earth tonight, respectively.
Wednesday, May 11
• Jupiter's strongly red Great Red Spot will be facing telescope users at nightfall in the Eastern and Central time zones. It transits Jupiter's central meridian around 10:48 p.m. EDT; 9:48 CDT.
Thursday, May 12
• The Arch of Spring spans the western sky in late twilight. Pollux and Castor form its top: they're lined up roughly horizontally in the west-northwest, about three finger-widths at arm's length apart. Look far to their lower left for Procyon, and farther to their lower right for Menkalinan and then bright Capella.
Friday, May 13
• As twilight fades, look above the first-quarter Moon for Regulus. Brighter Jupiter shines much farther to the Moon's upper left (for North America). They all descend to the southwest as night proceeds.
Saturday, May 14
• The two brightest things in the evening sky shine high just a few degrees apart this evening: the moon and Jupiter. Third brightest is Mars, low in the southeast after dark.
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.
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
Mercury and Venus are hidden in the glare of the Sun — except when Mercury transits the Sun's face during daytime on Monday the 9th! See Get Ready for May 9th’s Transit of Mercury and May 9th Transit of Mercury: Everything You Need to Know.
Mars (magnitude –1.7, in Scorpius) is closer, bigger, and brighter than it's been in a decade. It now rises in the southeast around the end of twilight, blazing brighter than Sirius (though still outdone by Jupiter). As it climbs higher, you'll find Antares 5° or 6° below it and Saturn about 9° to its lower left. This striking triangle stands highest in the south around 2 or 3 a.m., now with Saturn to Mars's left. By early dawn the triangle is lower in the southwest.
In a telescope Mars is a fine 17 arcseconds wide, nearly the 18.6 arcseconds it will reach when closest to Earth on May 30th. (Opposition is on the night of May 21–22.) 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 the June Sky & Telescope, page 48.
Jupiter (magnitude –2.2, in southern Leo) stands highest in the south at dusk, then starts declining toward the southwest. See our telescopic guide to Jupiter in the March Sky & Telescope, page 48.
Saturn (magnitude +0.2, between the legs of Ophiuchus above Scorpius) rises about a half hour after brighter Mars, following about 9° to Mars's lower left. By early dawn they're getting low in the south-southwest, with Saturn now upper left of Mars and fainter Antares about 5° under them.
Uranus is hidden low in the glow of dawn.
Neptune is very low in the east-southeast as dawn begins.
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.
“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