Some daily events in the changing sky for May 18 26.
Friday, May 18
Saturday, May 19
Sunday, May 20
Monday, May 21
Tuesday, May 22
Wednesday, May 23
Thursday, May 24
Friday, May 25
Saturday, May 26
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 standard is Sky Atlas 2000.0) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion or the enchanting though somewhat dated Burnham's Celestial Handbook). Read here how to use them most effectively.
More beginners' tips: "How to Start Right in Astronomy".
This Week's Planet Roundup
Mercury (about magnitude 0.5) is visible low in the sunset, getting higher every day. Look for it 45 to 60 minutes after sunset above the west-northwest horizon, far lower right of Venus. The much fainter star Beta Tauri is above Mercury early in the week (as shown at the top of this page), but to the right of it by week's end.
Venus (magnitude 4.3, in central Gemini) is the brilliant "Evening Star" shining in the west during and after twilight. This month Venus is at its peak evening height for the year.
Above Venus are Pollux and Castor. Watch them slide down toward the bright planet day by day. A telescope will show that Venus is nearing its half-lit phase, while enlarging a little week by week.
Mars (magnitude +0.9, in Pisces) is still low in the east-southeast during dawn. Though it remains pathetically tiny for now — a mere 5.5 acrseconds in apparent diameter, a featureless little blob in most scopes — be patient. Earth is catching up to Mars in our faster orbit around the Sun. When we pass it this December, Mars will appear nearly 16" wide. That still won't be very large, however; Mars was 25" wide around its opposition in August 2003.
Jupiter (magnitude 2.6, in southern Ophiuchus) rises in the east-southeast around 9 or 10 p.m. daylight saving time and dominates the south to southwest in the early-morning hours. Antares, less bright, sparkles 8° or 9° to Jupiter's right during the evening and lower right before dawn.
Saturn (magnitude +0.5, at the Leo-Cancer border) shines high in the west during evening. It's far to the upper left of bright Venus (by 35° to 30° this week). Watch these two closing in on each other, on their way toward their close conjunction at the end of June.
Regulus, less bright at magnitude +1.4, is 11° to Saturn's left or upper left. North of Regulus is 2nd-magnitude Algieba (Gamma Leonis), a fine telescopic double star.
Uranus (magnitude 6, in Aquarius) is low in the east-southeast before dawn, upper right of Mars.
Neptune (magnitude 8, in Capricornus) is higher in the southeast before dawn.
Pluto (magnitude 14, in northwestern Sagittarius) is not far from Jupiter in the south during the early morning hours.
All descriptions that relate to your horizon including the words up, down, right, and left are written for the world's midnorthern 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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