■ 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, as shown below. Its precise position will depend on your location and time.

Cover the Moon with a fingertip to help reveal the stars. Watch the Moon pull away eastward from them along its orbit through the night.

Full Moon in Leo at dusk, Feb. 23-24, 2024
Once it's finally dark Friday evening, cover the dazzling full Moon with your fingertip to reveal the stars nearby.

■ It isn't spring for another month, but the Spring Star Arcturus seems eager to hoist 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.


■ February has been Orion's month to stand at his highest in the south in early evening. But down behind him follows his dog, Canis Major, sporting brilliant Sirius on his chest.

Sirius is not only the brightest star in our sky after the Sun, it's also the closest naked-eye star after the Sun, at 8.6 light-years, for those of us at mid-northern latitudes.

Alpha Centauri is the actual closest star at 4.3 light-years, but you have to be farther south to see it. And in the northern sky three dim red dwarfs are closer than Sirius, but these require binoculars or a telescope.


■ Another way Sirius is special: it's the bottom star of the bright, equilateral Winter Triangle. The other two stars of the Triangle are orange Betelgeuse to Sirius's upper right (Orion's shoulder) and Procyon to Sirius's upper left. The Winter Triangle perfectly balances on Sirius in early evening.


■ A real Sirius challenge: Have you ever tried for Sirius B, the famous white dwarf? Sirius A and B are now at their widest apparent separation in 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 your target standing at its highest like it does now after dinnertime. Use the 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.


■ This is a fine week to look for the zodiacal light if you live in the mid-northern latitudes, now that the early-evening sky is moonless and the ecliptic is tilting high upward from the western horizon at nightfall. From a clear, clean-aired dark site, look west at the very end of twilight for a vague but huge, tall pyramid of pearly light. It's tilted to the left, aligned along constellations of the zodiac.

What you're seeing is sunlit interplanetary dust orbiting the Sun near the ecliptic plane.


■ After dinnertime at this time of year, five carnivore constellations are rising upright in a row from the northeast to south. They're all presented in profile with their noses pointed up and their feet (if any) to the right. These are Ursa Major the Big Bear in the northeast (with the Big Dipper as its brightest part), Leo the Lion in the east, Hydra the Sea Serpent in the southeast, Canis Minor the Little Dog higher in the south-southeast, and bright Canis Major the Big Dog in the south.


■ High in the northern sky these evenings, in the seemingly empty wastes between Capella overhead and Polaris due north, sprawls big, dim Camelopardalis, the Giraffe — perhaps the biggest often-visible constellation you don't know. Unless you have a good dark sky, you'll need binoculars to work out its large, nondescript pattern using the constellation chart in the center of Sky & Telescope — a challenge project that will build your skills for correctly relating what you see in binoculars to what you see, much smaller, on a sky map.

If you're new at this, start with brighter, easier constellations and save the shy Giraffe until you get good at it.


■ Sirius blazes high in the south on the meridian by about 8 p.m. now. Using binoculars or a scope at low power, examine the spot 4° south of it (directly below it when on the meridian). Four degrees is somewhat less than the width of a typical binocular's or finderscope's field of view. Can you see a little patch of speckly gray haze? That's the open star cluster M41, about 2,300 light-years away. Its total magnitude adds up to 5.0.

Sirius, by comparison, is only 8.6 light-years away — and being so near, it shines some 400 times brighter than the entire cluster.

■ Late these moonless evenings, as Ursa Major climbs high in the northeast, go on a telescopic galaxy hunt in and around its star pattern with Ted Forte's "Galaxy-Hopping in the Great Bear" in the March Sky & Telescope, page 18.


■ The last-quarter Moon rises around 1 or 2 a.m. tonight. (It's exactly last quarter at 10:23 a.m. EST Sunday morning.) The rising Moon shines very close to Antares, especially as seen from the East Coast. In fact the Moon occults Antares soon after rising as seen from much of the American South and Midwest.

Map and timetables for this event. The first two tables, for many cities, are very long. The first gives the times of Antares's disappearance behind the Moon's bright limb; the second its reappearance out from behind the Moon's dark limb. Scroll to be sure you're using the correct table; watch for the new heading as you scroll down. The first two letters in each entry are the country abbreviation. The times are in UT (GMT) March 3rd. UT is 5 hours ahead of Eastern Standard Time, 6 hours ahead of CST, 7 ahead of MST, and 8 ahead of PST.

For instance: Use the first table to see that for Atlanta, Antares disappears on the bright limb at 2:04 a.m. March 3rd EST when the Moon is only 4° high in the east-southeast (azimuth 126°). Then it reappears from behind the dark limb at 2:56 a.m. EST when the Moon is 13° high in the southeast. The latter is clearly the better event!

By dawn on the 3rd, the Moon has moved farther to Antares's east as indicated below.

The waning Moon before dawn crosses Scorpius and Sagittarius, March 2-6, 2024.
In the summer-preview sky that we see before dawn, the waning Moon crosses Scorpius and Sagittarius.


■ Look east after dusk this week for the constellation Leo already climbing well up the sky. Its brightest star is Regulus. The Sickle of Leo (about a fist and a half tall) extends upper left from there.

■ These moonless nights are a fine time to collect some telescopic triple stars with Bob King's new guide to 17 of them: Winter's Finest Triple Stars, with finder charts and data about each trio. Yes, Iota Cancri and Beta Mon are famous. Bet you didn't know about the others.

This Week's Planet Roundup

Mercury is out of sight in conjunction with the Sun.

Venus, magnitude –3.9, rises in the southeast while dawn is brightening. Try for it very low maybe 40 or 30 minutes before sunrise.

Mars, magnitude +1.3, remains near Venus but is less than 1% as bright.

Jupiter, magnitude –2.2 in Aries, is the bright white dot high in the west in twilight; lower as evening grows later. It sets around 10 or 11 p.m. In a telescope, Jupiter has shrunk to only 36 arcseconds wide.

Jupiter is now 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 cross the line between those two. The three form a perfectly straight line on Wednesday the 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 in conjunction with the Sun.

Uranus, magnitude 5.7 in Aries, is 9° above Jupiter. Use the finder charts in last November's Sky & Telescope, pages 48-49.

Neptune is lost in the afterglow of sunset.

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 if you want, rather than only slowly by the electric motors.

However, finding faint telescopic objects 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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