Some daily events in the changing sky for January 9 – 17.
Friday, January 9
Saturday, January 10
Sunday, January 11
Monday, January 12
Tuesday, January 13
Wednesday, January 14
Thursday, January 15
Friday, January 16
Saturday, January 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 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 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 is dropping low after sunset and is also fading fast. Early in the week it's still fairly easy to spot at magnitude 0 just above the west-southwest horizon in mid-twilight, very far to the lower right of Venus. But by the end of the week it's lost from view.
Venus (magnitude –4.5) is the dazzling "Evening Star" in the southwest during and after twilight. It doesn't set now until as late as about 9 p.m.
In a telescope Venus is 24 arcseconds wide and near dichotomy: half-lit. Venus will be exactly 50% illuminated on the evening of January 16th. But because the sunlight illumination is dimmer at the terminator, in a telescope the waning Venus usually looks exactly half-lit 5 or 10 days earlier than when it really is. How well can you determine this date? Telescopically, Venus is best seen in bright twilight or even broad daylight. (It's less glary when seen against a bright sky, and it's also higher.)
Mars remains hidden deep in the glow of sunrise.
Jupiter (magnitude –1.9) is pretty completely lost deep in the glow of sunset now. It you want to try for it anyway, use binoculars to look below Mercury shortly after sunset early in the week, as shown at the top of this page.
Saturn (magnitude +1.0, near the Leo-Virgo border) rises around 9 or 10 p.m. It's highest in the south around 3 or 4 a.m. Don't confuse Saturn with similarly-bright Regulus 22° (about two fist-widths at arm's length) to its upper right after they rise, and more directly to its right in the early-morning hours.
This week Saturn's rings are 0.9° to 1.0° from edge on. The rings will gradually open to 4° by late May, then will close to exactly edge-on early next September — when, unfortunately, Saturn will be out of sight in conjunction with the Sun. Saturn will again be poorly placed for our next ring-plane crossing 15 years hence. So now is the thinnest you can see Saturn's rings until 2038!
Uranus (magnitude 5.9, in Aquarius) is upper left of Venus in the evening sky. Use binoculars with our article and finder chart.
Neptune is getting lost in the sunset.
Pluto is hidden in the glow of sunrise.
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 Standard Time (EST) equals Universal Time (known as UT, UTC, or GMT) minus 5 hours.
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