Some daily events in the changing sky for April 10 – 18.
Forgotten but not gone? Comet Lulin remains within telescopic reach at 9th magnitude, in the feet of Gemini in the western sky just after dark. The window of moonless early evenings begins opening around Saturday April 11th. Use our chart. Good luck.
The Comet Yi-SWAN challenge. It isn't much at magnitude 8½, but this new comet is far north crossing the bright pattern of Cassiopeia this week. It's getting quite low in the northwest just after dusk — lower than it is in the northeast just before the first light of dawn. However, the Moon was full on Thursday the 9th, so the only moonless time to look for the comet this week will be right after dusk, starting about April 11th. Next week will be better, with the comet higher before dawn (but no brighter). See our AstroAlert with the comet's positions for plotting on your star atlas. Again, good luck.
Friday, April 10
Saturday, April 11
Sunday, April 12
Monday, April 13
Tuesday, April 14
Wednesday, April 15
Thursday, April 16
Friday, April 17
Saturday, April 18
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 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 even more detailed 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? 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 and a curious mind." Without these, they note, "the sky never becomes a friendly place."
More beginners' tips: "How to Start Right in Astronomy".
This Week's Planet Roundup
Mercury (about magnitude –1) has its best evening apparition of the year this week and next. Look for it low in the west about 40 minutes after sunset. It gets higher later in the week.
Venus (magnitude –4.5) is low in the dawn. Look for it above the eastern horizon about 60 to 30 minutes before sunrise. Don't confuse it with Jupiter, higher and far to the right in the southeast. (You can find your local sunrise time from our online almanac. If you're on daylight saving time like most of North America, make sure the Daylight Saving Time box is checked.)
In a telescope, Venus is a thickening and shrinking crescent. The best telescopic views come in full morning daylight, with Venus higher in steadier air.
Mars (magnitude +1.2) is very low in the sunrise glow, to the lower right of Venus. Use big binoculars. Good luck.
Jupiter (magnitude –2.1, in Capricornus) shines in the southeast during early dawn.
Saturn (magnitude +0.6, near the hind foot of Leo) shines high in the southeast at dusk and highest in the south around 9 or 10 p.m. Regulus, a little less bright, sparkles 16° (roughly one and a half fist-widths at arm's length) to Saturn's upper right in early evening, and more directly to its right in late evening.
In a telescope, Saturn's rings are 4° from edge on. They'll close to exactly edge-on next September 4th, when, unfortunately, Saturn will be out of sight practically in conjunction with the Sun.
Uranus (6th magnitude) is hidden low in the sunrise glow, in the background of Venus and Mars.
Neptune (8th magnitude) is also in the glow of dawn, in the background of Jupiter.
Pluto (14th magnitude, in northwestern Sagittarius) is in the south-southeast before the first light of 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 (known as UT, UTC, or GMT) minus 4 hours.
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