Some daily events in the changing sky for April 23 May 1.
Friday, April 23
Saturday, April 24
Sunday, April 25
Monday, April 26
Tuesday, April 27
Wednesday, April 28
Thursday, April 29
Friday, April 30
Saturday, May 1
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 map in the center of 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 must have a detailed, large-scale sky atlas (set of charts). The standards are the Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger Sky Atlas 2000.0 (stars to magnitude 8.5); and the even larger and deeper Uranometria 2000.0 (stars to magnitude 9.75). And read how to use your charts effectively.
You'll also want a good deep-sky guidebook, such as Sky Atlas 2000.0 Companion by Strong and Sinnott, or the more detailed and descriptive Night Sky Observer's Guide by Kepple and Sanner or the classic if dated Burnham's Celestial Handbook.
Can a computerized telescope take their place? I don't think so not for beginners, anyway, and especially not on mounts that are less than top-quality mechanically. 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 RoundupMercury is lost in the glare of the Sun.
Venus (magnitude 3.9, in Taurus) shines brightly in the west-northwest during twilight. The Pleiades glimmer into view near it as the sky darkens. Venus is creeping a little higher each week; the Pleiades are sinking lower, passing to the planet's right. Also, look for orange Aldebaran to Venus's left or upper left.
Mars, dimming farther into the distance at magnitude +0.6 now, is high in the southwest during evening. It's in Cancer east of the Beehive Star Cluster (use binoculars). In a telescope Mars is gibbous and shrinking: from 7.6 to 7.2 arcseconds in diameter this week. Can you still see its north polar cap? The cap is dwindling rapidly now in the late spring of Mars's northern hemisphere.Jupiter (magnitude 2.1) is low in the dawn. Look for it above the eastern horizon about 60 to 45 minutes before your local sunrise time. Nothing else there is nearly so bright.
Saturn (magnitude +0.7, in the head of Virgo) is high in the south during evening. In a telescope Saturn's rings are tilted only 2.1° from edge-on, practically at the minimum inclination of 1.7° that they'll display from mid-May through early June. Note the fine black shadow-line they cast on Saturn's disk. Now is also a fine time to try for the more difficult of Saturn's moons with your telescope; see the May Sky & Telescope, page 61.
Uranus and Neptune are still in the glow of sunrise. Wait another few weeks.
Neptune, however, is passing a historic milestone this month. For the first time since it was discovered in 1846, Neptune has completed a full circuit of the sky and has returned very close to the point (near the Aquarius-Capricornus border) where Johann Galle first spotted it from Berlin Observatory on September 23rd of that year following a prediction by Urbain Le Verrier in France that a new planet should be there, based on gravitational perturbations of Uranus. See The Return of Neptune.Pluto (magnitude 14, in northwestern Sagittarius) is highest in the south before dawn.
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 (also known as UT, UTC, or GMT) minus 4 hours.
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