Sky This Week

What to look for in the Night Sky this week with a quick Survey at the bottom.


■ 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.



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.

Courtesy of Sky & Telescope senior editor Alan MacRobert
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