Some daily events in the changing sky for April 9 – 17.
Friday, April 9
Saturday, April 10
Sunday, April 11
Monday, April 12
Tuesday, April 13
Wednesday, April 14
Thursday, April 15
Later, as Mercury and the Moon set and night comes on, the huge, tall, tilted pyramid of the zodiacal light will come into view — if you're far from light pollution.
Friday, April 16
Saturday, April 17
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'll need a detailed, large-scale sky atlas (set of charts; the standards are Sky Atlas 2000.0 or the smaller Pocket Sky Atlas) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion by Strong and Sinnott, the more detailed and descriptive Night Sky Observer's Guide by Kepple and Sanner, or the classic Burnham's Celestial Handbook). Read how to use them effectively.
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 Roundup
Mercury and Venus are still together in the west-northwest during twilight, but Mercury is fading fast as it drops away from bright Venus. Look for it to Venus's lower right, farther every day. Venus is magnitude –3.9. Mercury is magnitude +0.1 on April 9th, +0.5 on the 11th, +0.9 on the 13th, +1.4 on the 15th, and +2.0 on the 17th.
Have you ever viewed Mercury as a tiny crescent in a telescope? Now's the time to try; see chart. The best views come long before sunset. See the April Sky & Telescope, page 53, for more on observing this tricky planet telescopically.
Mars, dimming into the distance at magnitude +0.4, shines very high in the southwest during evening. It's in Cancer, left of Pollux and Castor and above Procyon. With binoculars, watch Mars closing in on the Beehive Star Cluster, M44. At the end of the week Mars passes just to the cluster's north.
In a telescope Mars is gibbous and shrinking: from 8.6 to 8.0 arcseconds in diameter this week. Can you still see its north polar cap, diminishing as the Sun rises higher on it in the Martian spring?
Jupiter (magnitude –2.1) is low in the glow of dawn. Look for it just above the eastern horizon about 40 minutes before your local sunrise time.
Saturn (magnitude +0.7, in the head of Virgo) is in the southeast after dark and shines highest in the south around 11 p.m. In a telescope Saturn's rings are tilted only 2.4° from edge-on. They'll narrow to 1.7° from mid-May through early June, then begin widening again.
Uranus and Neptune are hidden in the glow of sunrise.
Pluto (magnitude 14, in northwestern Sagittarius) is highest in the south just 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.
"Rational and innocent entertainment of the highest kind."
— John Mills, 19th century Scottish manufacturer and founder of Mills Observatory, on amateur astronomy.
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