■ First-quarter Moon tonight (exactly first-quarter at 10:01 a.m. on this date EST). Just lower right of the Moon, by about 2° or 3° for North America, spot the Pleiades as shown below. Their tiny dipper shape sits horizontal at nightfall. The Moon passes closer by the Pleiades for Europe. It occults some of them for southern Africa.

Moon passing the Pleiades and Aldebaran, Feb. 16-17, 2024
The first-quarter Moon joins the Pleiades and Aldebaran this evening. (The Moon is shown about three times its actual apparent diameter.)


■ Right after night is completely dark, the W of Cassiopeia shines high in the northwest, standing almost on end. Near the zenith is bright Capella.

The brightest star about midway between Cassiopeia and Capella (and a little to the left) is Alpha Persei, magnitude 1.8. It lies on the lower-right edge of the Alpha Persei Cluster: a large, elongated, very loose swarm of fainter stars about the size of your thumbtip at arm's length. At least a dozen are 6th magnitude or brighter, bright enough to show well in binoculars even through the moonlight this evening.

Alpha Per, a white supergiant, is a true member of the group and is its brightest light. It and the rest are about 560 light-years away.


■ Canopus, the second-brightest star after Sirius, happens to lie almost due south of Sirius: by 36°. That's far enough south that it never appears above your horizon unless you're below latitude 37° N (southern Virginia, southern Missouri, central California). And near there, you'll need a very flat south horizon.

Canopus crosses the south point on your horizon just 21 minutes before Sirius does. So, when to look? Canopus is due south when Beta Canis Majoris — Murzim the Announcer, the star about three finger-widths to the right of Sirius — is at its highest due south over your landscape. That's about 8 or 9 p.m. now, depending on how far east or west you live in your time zone. Drop straight down from Murzim then.

■ Algol should be at minimum light, magnitude 3.4 instead of its usual 2.1, for about two hours centered on 8:21 p.m. EST. Comparison-star chart (with north up. Celestial north is the direction to Polaris as you look across the sky.)


■ Face southeast after dark. The bright gibbous Moon shines about midway between Procyon below it and brighter Capella near the zenith.

To the right of the Moon, Aldebaran and the Pleiades stack themselves above Orion.

Much closer to the Moon's left or lower left are Pollux and, above it, slightly fainter Castor.


■ The waxing gibbous Moon shines close to Pollux this evening, while Castor watches from a little above. Binoculars help through the moonlight.


■ Not long after dark, the Big Dipper, standing on its handle, is as high in the northeast as Cassiopeia has descended to in the northwest. Cas also is standing on end. The wheel of the year is turning.

A dawn challenge. Venus and Mars are in conjunction Thursday morning, just above the east-southeast horizon when dawn is brightening as shown below. About 40 minutes before sunrise, pick up Venus only a few degrees above the true horizon. Then, use a telescope to try for the tiny orange fuzzblob of Mars 0.6° to Venus's lower left. Good luck. Mars is only 1/120 as bright!

Venus and Mars will be in conjunction just above the east-southeast horizon as dawn brightens on the morning of Feb. 22, 2024.
Venus and tiny, faint, difficult Mars will be in close conjunction just above the east-southeast horizon as dawn brightens Thursday morning. (The visibility of the faint objects in bright twilight is exaggerated.)


■ The Moon this evening forms an isosceles (two sides equal) triangle with, to its lower left, two stars of Leo: Regulus and lesser Gamma Leonis (Algieba).


■ It's not spring for another month, but the Spring Star Arcturus seems eager to thrust itself into view. It rises above the east-northeast horizon soon after dusk now, depending on your latitude.

To see where to watch for this, find the Big Dipper as soon as the stars come out; it's high in the northeast. Follow the curve of its handle down and around to the lower right by a little more than a Dipper-length. That's the spot on the horizon to watch.

By 10 or 11 p.m. Arcturus dominates the eastern sky.

■ Full Moon tonight (exactly full at 7:30 a.m. Saturday morning EST). At sunset the Moon is already rising in the east. By nightfall you'll see that the Moon is almost straight between Regulus 3° to its right and lesser Gamma Leonis 5° to the Moon's left. Binoculars will help you spot them through the moonlight, especially if there's any haze in the sky.

Watch the Moon pull away eastward from those stars through the hours of the night.


■ Have you ever tried for Sirius B, the famous white dwarf? Sirius A and B are now at the widest apparent separation of their 50-year orbit, 11 arcseconds apart, and will remain so for the next couple years before they start closing up again. You'll want at least an 8-inch telescope (preferably larger), a night of really excellent steady seeing (keep checking night after night; the seeing makes all the difference for spotting Sirius B), extreme high power, and Sirius standing at its highest like it is now. See the Sirius-B-hunting tips in Bob King's article Sirius B – A New Pup in My Life.

The Pup is east-northeast of the Dog Star and 10 magnitudes fainter: one ten-thousandth as bright. As Bob recommends, put a homemade occulting bar across your eyepiece's field stop: a tiny strip of aluminum foil held to the field stop with a bit of tape, with one edge crossing the center of the field. Use a pencil point to nudge the edge of the foil into sharp focus as you look through the eyepiece, holding it up to the light indoors.

In the telescope, rotate the eyepiece and hide blinding Sirius A just behind the strip's east-northeastern edge.


■ It's not spring for another month, but the Spring Star Arcturus seems eager to thrust itself into view. It rises above the east-northeast horizon around 8 or 9 p.m. now, depending on your latitude.

To see where to watch for this, find the Big Dipper as soon as the stars come out; it's high in the northeast. Follow the curve of its handle down and around to the lower right by a little more than a Dipper-length. That's the spot on the horizon to watch.

By 10 or 11 p.m. Arcturus dominates the east.

This Week's Planet Roundup

Mercury is out of sight in conjunction with the Sun.

Venus, magnitude –3.9, rises in the southeast as dawn gets under way. It's still hanging low there when dawn grows too bright for it.

Mars, magnitude +1.3, remains deep in the sunrise.

Jupiter, magnitude –2.2 in Aries, is the bright white dot high in the southwest at dusk; lower in the west-southwest later. It sets in the west by about 11 p.m. In a telescope, Jupiter has shrunk to only 36 arcseconds wide.

Jupiter is now almost midway between Hamal (Alpha Arietis) a fist-width to its right, and Menkar (Alpha Ceti) a fist-width to its left. The two stars are magnitudes 2.0 and 2.5, respectively. As Jupiter creeps eastward against the stars this week, watch it draw closer to the line between those two. The three will form a perfectly straight line on February 28th.

Jupiter with Great Red Spot, Jan. 17, 2024
Jupiter's Great Red Spot side on January 17th, imaged by Christopher Go. South here is up. The Red Spot has become paler and less prominent in recent years. We've adjusted the contrast of the image to approximate Jupiter's visual appearance. To get a better idea of Jupiter as seen in a telescope at high power, stand far back from your screen and squint a bit.

Saturn is lost deep in the sunset.

Uranus, magnitude 5.7 in Aries, is 10° upper left of Jupiter. In a telescope at high power Uranus is a tiny but distinctly nonstellar ball, 3.7 arcseconds in diameter. Locate and identify it using the finder charts in the November Sky & Telescope, pages 48-49.

Neptune, magnitude 7.9, is lost in the evening twilight.

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 and graphics that also depend on longitude (mainly Moon positions) are for North America.

Eastern Standard Time (EST) is Universal Time minus 5 hours. UT is also known as UTC, GMT, or Z time.

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 a more detailed 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.

Once you get a telescope, to put it to good use you'll need a much more detailed, large-scale sky atlas (set of charts). The basic standard is the Pocket Sky Atlas (in either the original or Jumbo Edition), which shows all stars to magnitude 7.6.

Pocket Sky Atlas cover, Jumbo edition
The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and hundreds of telescopic galaxies, star clusters, and nebulae among them. Shown here is the Jumbo Edition, which is in hard covers and enlarged for easier reading outdoors by red flashlight. Sample charts. More about the current editions.

Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; nearly three times as many. The next up, once you know your way around, are the even larger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to mag 9.75). And read How to Use a Star Chart with a Telescope. It applies just as much to charts on your phone or tablet as to charts on paper.

You'll also want a good deep-sky guidebook. A beloved old classic is the three-volume Burnham's Celestial Handbook. An impressive more modern one is the big Night Sky Observer's Guide set (2+ volumes) by Kepple and Sanner.

Can computerized telescopes replace charts? Not for beginners I don't think, especially not on mounts and tripods that are less than top-quality mechanically. Unless, that is, you prefer spending your time getting finicky technology to work rather than learning the sky. And 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."

If you do get a computerized scope, make sure the drives can be disengaged so you can swing it around and point it readily by hand rather than only slowly by the electric motors.

However, finding a faint telescopic object the old-fashioned way with charts isn't simple either. Learn the tricks at How to Use a Star Chart with a Telescope

Audio sky tour. Out under the evening sky with your
earbuds in place, listen to Kelly Beatty's monthly
podcast tour of the naked-eye heavens above. It's free.

"The dangers of not thinking clearly are much greater now than ever before. It's not that there's something new in our way of thinking, it's that credulous and confused thinking can be much more lethal in ways it was never before."
            — Carl Sagan, 1996

"Facts are stubborn things."
             John Adams, 1770


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