All five naked-eye planets are visible in early dawn — and Mercury is easier this week than last. See our article It's Not Over Till the Fast Planet Sinks. Media and bloggers: Use the info and graphics in our press release.
Friday, January 29
• Sirius blazes high in the south on the meridian by about 10 p.m. now. Using binoculars, examine the spot 4° south of Sirius (directly below it when on the meridian). Four degrees is somewhat less than the width of a typical binocular's field of view. Can you see a little patch of gray haze there? That's the open star cluster M41, about 2,200 light-years away. Sirius, by contrast, is only 8.6 light-years away. No wonder it looks so bright.
• The eclipsing variable star Algol will be at its minimum light, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 9:05 p.m. EST.
• If you go out Saturday morning for the dawn planet panorama, you'll find the waning Moon upper left of Spica, as shown above. Off to their left, Mars will be 1½° above fainter Alpha Librae, a wide binocular double star.
Saturday, January 30
• As soon as it's fully dark, spot the equilateral Winter Triangle in the southeast. Sirius is its brightest and lowest star. Betelgeuse stands above Sirius by about two fists at arm's length. To the left of their midpoint shines Procyon.
And standing directly above Procyon now (depending on your latitude) is 3rd-magnitude Beta Canis Minoris, the only other easy naked-eye star of Canis Minor.
Sunday, January 31
• Algol should be at minimum light for a couple hours centered around 5:54 p.m. EST. Watch it brighten through the rest of the evening.
• Last-quarter Moon tonight (exact at 10:28 p.m. EST). The Moon rises around 1 a.m. tonight, in company with Mars. By the dawn of Monday the 1st they're high in the south. Look for 3rd-magnitude Alpha Librae (Zubenelgenubi) 1° south of Mars.
Monday, February 1
• In early dawn of Tuesday the 2nd, the Moon shines over the head of Scorpius about midway between Mars and Saturn.
Tuesday, February 2
• In early dawn of Wednesday the 3rd, you'll find Saturn and Antares below the waning Moon, as shown above.
Wednesday, February 3
• Orion stands high in the southeast to south these evenings, proudly displaying the sky's brightest orange-red supergiant, Betelgeuse, in his armpit. But did you know about the redder carbon stars glimmering faintly elsewhere in upper Orion? See the February Sky & Telescope, page 44, and tote out your scope.
Thursday, February 4
• In early dawn Friday morning the 5th, catch the crescent Moon pointing the way down to Venus and Mercury, as shown at right.
Friday, February 5
• On Saturday morning the 6th, the crescent Moon, vibrant Venus, and shy Mercury form a triangle low in the southeast, as shown here.
Saturday, February 6
• Bright Capella high overhead, and equally bright Rigel in Orion’s foot, are at almost the same right ascension. This means they cross your sky’s north-south meridian at almost the same time (around 8 p.m. now, depending on how far east or west you live in your time zone). So whenever Capella passes its very highest overhead, Rigel marks true south over your landscape. And vice versa.
Want to become a better astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.
This is an outdoor nature hobby. 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 guide to astronomy.
Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The basic standard is the Pocket Sky Atlas (in either the original or new Jumbo Edition), which shows stars to magnitude 7.6.
Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5, nearly three times as many. Next up, once you know your way around, is the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.
You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, or the bigger Night Sky Observer's Guide by Kepple and Sanner.
Can a computerized telescope replace charts? Not for beginners, I don't think, and not on mounts and tripods that are less than top-quality mechanically (meaning heavy and expensive). 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
All five classical naked-eye planets are visible during dawn, as shown at the top of this page.
Mercury and Venus are low in the southeast. Look about 45 to 60 minutes before your local sunrise time. Venus is bright and obvious at magnitude –3.9. Look lower left of it for fainter Mercury, magnitude 0. They're 8° apart on the morning of January 30th, and 5° apart by the time the Moon poses with them on February 5th and 6th.
Saturn (magnitude +0.5, in Ophiuchus) shines in the south-southeast, far to Venus's upper right. Spot twinkly orange Antares (magnitude +1.1) 8° to the lower right of Saturn. In a telescope, Saturn's rings this year are tilted a wide-open 26° from edgewise.
Mars (magnitude +0.8, in Libra), glows yellow-orange farther to the upper right: due south in early dawn. In a telescope it's still a small 7 arcseconds in diameter. Notice its gibbous shape; Mars is nearly at western quadrature (90° west of the Sun). Mars will be more than twice as wide, 18.6 arcseconds, when closest to Earth in late May and early June.
Jupiter (magnitude –2.4, between Leo and Virgo) rises in the east around 8 or 9 p.m., shines highest in the south around 2 or 3 a.m., and moves over to dominate the southwest by the time the other planets are up in early dawn.
Uranus (magnitude +5.9, in Pisces) is still in the west right after dark. Finder chart.
Neptune (magnitude +8.0, in Aquarius) is sinking away into the sunset.
Planet Nine (probably fainter than magnitude 22, and probably not in the zodiac) seems reasonably likely to be out there, but we can't say where. It could be anywhere along a wide sheaf of orbits supposedly inclined roughly 30° to the ecliptic. And it's most likely to be near its aphelion, hundreds or even 1,000 a.u. away.
All descriptions that relate to your horizon — 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) is Universal Time (UT, UTC, or GMT) minus 5 hours.
“This adventure is made possible by generations of searchers strictly adhering to a simple set of rules. Test ideas by experiments and observations. Build on those ideas that pass the test. Reject the ones that fail. Follow the evidence wherever it leads, and question everything. Accept these terms, and the cosmos is yours.”
— Neil deGrasse Tyson