This Week's Sky at a Glance, March 6 – 15

FRIDAY, MARCH 6

■ Pollux and Castor in Gemini, with their overpowering visitor Jupiter, pass nearly overhead in mid-evening this week if you live in the world's mid-northern latitudes. The Twin's head stars go smack overhead if you're near latitude 30° north: Austin, Houston, the US Gulf Coast, northernmost Africa, Tibet, Shanghai.

The "twin" heads of the Gemini figures are fraternal twins at best. Pollux is visibly brighter than Castor, and it is pale orange-yellow compared to Castor's white. And as for their physical nature, they're not even the same species.

Pollux is a single orange giant. Castor is a binary pair of two much smaller, hotter, white main-sequence stars, a fine double in amateur telescopes. A scale model: if Castor A and B were a tennis ball and a golf ball, they'd be about a half mile apart.

Moreover, Castor A and B are each closely orbited by an unseen red dwarf — a dim marble in our scale model, each just a foot or so from its white-hot primary.

And a very distant tight pair of red dwarfs, Castor C, is visible in amateur scopes as a single, 10th-magnitude speck 70 arcseconds south-southeast of the main pair. In our scale model, they would be a pair of marbles about 3 inches apart at least 10 miles from Castor A and B.

Space is big.

SATURDAY, MARCH 7

■ After sundown this evening and tomorrow evening, Saturn will be just 1.1° from Venus very low in the west. It's upper left of Venus this evening, then lower left of it tomorrow evening as shown in the scene below.

Find a spot with a very low view due west, and bring binoculars or a wide-field telescope. Good luck. Saturn will be only 1/100 as bright as Venus!

■ Daylight-saving time, observed in most of North America, begins at 2:00 a.m. Sunday morning. Clocks "spring ahead" one hour. Daylight time for North America runs from the second Sunday in March to the first Sunday in November; the rules last changed in 2007. Daylight time is not used in Hawaii, Saskatchewan, Puerto Rico, or in most of Arizona.

SUNDAY, MARCH 8

■ Arcturus, the Spring Star, now rises in the east-northeast about an hour after complete nightfall, depending on your latitude. It climbs higher in the east into better visibility later in the evening, shining brightly. By modern measurements Arcturus is visual magnitude –0.05, making it the fourth-brightest nighttime star. It's bested only by Sirius, Canopus, and Alpha Centauri (counting the combined light of Alpha Cen A and B; they appear single to the unaided eye).

For northerners who can never see Canopus or Alpha Cen, Arcturus is outshone by Sirius alone, which now glitters toward the south-southwest after dark. However, Vega and Capella are very close on the heels of Arcturus, brightness-wise.

MONDAY, MARCH 9

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

■ Many binocular observers check in on the 5th-magnitude open cluster M41 just 4° south of Sirius. And now the sky is free of troublesome moonlight in early evening. But how many observers then look the other way from Sirius for the cluster M50? It's 10° north-northeast from Sirius, dimmer, smaller and more subtle than M41.

Find it by sweeping from Sirius first to Theta Canis Majoris, the 4th-magnitude pointy nose of the Big Dog's stick figure, then on again nearly as far in the same direction and just a touch to the left. M50 is not exactly easy, but it's there. I can spot it without too much difficulty using 10x50 binoculars through moderate suburban light pollution. Averted vision helps.

If you're trying under difficult conditions, get more detailed guidance using the Pocket Sky Atlas, chart 27. The more exactly you know the spot to examine for a difficult deep-sky object, the more likely you are to be able to detect it. Take time. Keep at it.

M41 is about 2,300 light-years from us; M50 is about 2,900.

■ A double eclipse-emergence of Jupiter's satellites happens for East Coast telescope users. Io will reappear out of Jupiter's shadow at 8:12 p.m. EST, followed by slower-moving Callisto reappearing more slowly 25 minutes later, at 8:37 p.m. EST.

Watch for Io to emerge about half a Jupiter-diameter east of Jupiter's edge. Callisto reappears about three times farther out. It may still be twilight depending on your location, but Jupiter's moons show pretty well through late twilight.

■ Before dawn Tuesday morning, peek out a south window to greet the nearly-last-quarter Moon hanging less than 2° below orange Antares.

TUESDAY, MARCH 10

■ Jupiter's Great Red Spot should cross Jupiter's central meridian around 9:50 p.m. EDT.

■ Last-quarter Moon tonight (exactly last-quarter at 5:39 a.m. EDT Wednesday morning). The Moon rises around 3 a.m. local daylight-saving time. By the beginning of Wednesday's dawn it will be well up in the south-southeast in the feet of Ophiuchus, left of Scorpius.

WEDNESDAY, MARCH 11

■ Bright Sirius now stands due south on the meridian just as the last of twilight fades away. Sirius is the bottom star of the big, equilateral Winter Triangle. The triangle's other two stars are orange Betelgeuse to Sirius's upper right (Orion's shoulder) and Procyon to Sirius's upper left. This is the time of year when the Winter Triangle balances on Sirius shortly after dark.

THURSDAY, MARCH 12

■ As evening proceeds, Sirius shines brilliantly in the south-southwest. Lower left of it, by about one fist, is the triangle of Aludra, Wezen, and Adhara, from left to right. They form Canis Major's tail, rear end, and hind foot, respectively. Or alternatively, the handle and the lower end of the Meat Cleaver.

Just left or upper left of the triangle, forming a 3rd- and 4th-magnitude arc that's just a bit wider than the triangle, are the three uppermost stars of the constellation Puppis. This is not a puppy, despite following right behind the Big Dog. It's the Poop Deck (stern) of the giant ancient constellation Argo Navis, the ship of Jason and the Argonauts. These three are the only stars of Argo that are readily visible naked-eye from mid-northern latitudes.

Just 1.5° upper right of the middle of the three, binoculars on a dark night will show the little 6th-magnitude open cluster M93. It's elongated northeast-southwest. See Matt Wedel's Binocular Highlight column and chart in the March Sky & Telescope, page 43. He says that in big 15x binoculars, the cluster "has a distinct cat's-eye shape."

FRIDAY, MARCH 13

■ Big Dipper lore: The Big Dipper glitters softly high in the northeast these evenings, standing on its handle. You probably know that the two stars forming the front of the Dipper's bowl (currently on top) are the Pointers; they point to Polaris, currently to their left or lower left.

And, you may know that if you follow the curve of the Dipper's handle out and around by a little more than a Dipper length, you'll arc to Arcturus, now rising in the east-northeast.

But did you know that if you follow the Pointers backward the opposite way, you'll land in Leo? Go four or five fists at arm's length.

Draw a line diagonally across the Dipper's bowl from where the handle is attached, continue far on, and you go to Gemini (about four fists).

And look at the two stars forming the open top of the Dipper's bowl. Follow this line past the bowl's lip far across the sky, and you cruise to Capella (about five fists).

SATURDAY, MARCH 14

■ Little Dipper lore: Use the Pointer stars atop the Big Dipper, standing high in the northeast, to locate Polaris three fists to their left. It's the end of the Little Dipper's handle.

Polaris is a respectable 2nd magnitude. But other than Polaris, all you may see of the Little Dipper through light pollution are the two stars forming the outer edge of its bowl: Kochab (also 2nd magnitude) and below it Pherkad, 3rd magnitude. Find these two "Guardians of the Pole" about a fist and a half at arm's length to Polaris's lower right.

They're called the Guardians because they forever march around and around Polaris, which very nearly marks the North Celestial Pole.

Now is the time of year when the two Guardians line up exactly vertically around the end of twilight.

SUNDAY, MARCH 15

■ We're just five days from the official (astronomical) beginning of spring: Earth will cross the March equinox point in its orbit on March 20th this year, at 10:46 a.m. EDT.

■ On the traditional divide between the winter and spring sky lies the dim constellation Cancer. It's now very high toward the south-southeast in early evening, between Gemini to its west and Leo to its east.

Cancer holds something unique in its middle: the Beehive Star Cluster, M44. The Beehive shows dimly to the naked eye if you have little or no light pollution. Where to look? The Beehive is a bit less than halfway from Pollux in Gemini to Regulus in Leo. With binoculars it's easy, even under mediocre sky conditions. Look for a scattered clump of faint little stars, magnitudes 6½ on down.

Use a telescope to hunt out the much smaller, fainter open cluster M67 some 9° below the Beehive. Find M67 1.8° due west of 4th-magnitude Alpha Cancri.

---

This Week's Planet Roundup

Mercury and Mars are hidden in the glare of the Sun.

Venus, bright at magnitude –3.9, gleams low in the western twilight, a little less low each week. Look for it due west about 30 or 40 minutes after sunset. Around then it will still be almost a fist at arm's length above horizontal. It sets near the end of twilight.

Saturn is passing Venus far in the background. At magnitude +1.0 Saturn is only 1% as bright as Venus. Binoculars will help!

On Friday March 6th, find Saturn 2° upper left of Venus. That's hardly more than a finger's width at arm's length, or about a third the width of a typical binocular's field of view. On March 7th and 8th catch Saturn just 1.1° to Venus's left.

Each day after that, Saturn sinks another 1° below Venus until it's finally gone from view.

Jupiter is bright and easy nearly overhead as you face south when the stars come out. Jupiter shines at magnitude –2.4, making it the brightest point in the night sky. It soon shifts to the very high southwest, then moves lower as the evening grows late. Jupiter sets around 3 a.m.

In a telescope Jupiter is 42 arcseconds wide. It's been shrinking and fading a bit as Earth pulls farther ahead of it in our faster orbit around the Sun.

Uranus (magnitude 5.8, in Taurus 5° SSW of the Pleiades) is high in the southwestern sky these evenings. At high power in a telescope it's a tiny but non-stellar dot, 3.6 arcseconds wide. You'll need a detailed finder chart to identify it among similar-looking faint stars, such as the chart in last November's Sky & Telescope, page 49.

Neptune, at magnitude 8.0 near sinking Saturn, is completely lost in the 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. Eastern Daylight Time (EDT) is Universal Time minus 4 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.

For the attitude every amateur astronomer needs, read Jennifer Willis's Modest Expectations Give Rise to Delight.

Once you get a telescope, to put it to good use you'll want 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. Both show all 30,000 stars to magnitude 7.6, and 1,500 deep-sky targets — star clusters, nebulae, and galaxies — to search out among them.

Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; nearly three times as many, as well as many more deep-sky objects. It's currently out of print, but maybe you can find one used.

The next up, once you know your way around well, are the even larger Interstellarum Deep-Sky Atlas (with 201,000+ stars to magnitude 9.5 and 14,000 deep-sky objects selected to be detectable by eye in very large amateur telescopes), and Uranometria 2000.0 (332,000 stars to mag 9.75, and 10,300 deep-sky objects).

Read How to Use a Star Chart with a Telescope. It applies just as much to electronic charts on your phone or tablet — which many observers find handier and more versatile, if sometimes less well designed and contextualized, than charts on paper.

You'll also want a good deep-sky guidebook. A beloved old classic is the three-volume Burnham's Celestial Handbook. It was my bedside reading for years. An impressive more modern one is the big Night Sky Observer's Guide set (2+ volumes) by Kepple and Sanner. The pinnacle for total astro-geeks is the new Annals of the Deep Sky series, currently at 11 volumes as it works its way forward through the constellations alphabetically. So far it's up to H.

Can computerized telescopes replace charts? Well, I used to say this:

"Not for beginners, I don't think, unless you prefer spending your time getting finicky technology to work rather than learning how to explore through the sky yourself. 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, 'the sky never becomes a friendly place.' "

But, things change. The technology has continued to improve and become more user-friendly — particularly with software that can now recognize any star field to determine exactly where the telescope is pointed — finally bypassing all aiming imperfections in the mount, tripod, gears, bearings and other mechanics, or in the user's skill in setting up.

The latest revolution is the rise of small, imaging-only "smartscopes." These take advantage of not only today's pointing technology, but also the vastly better capabilities of imaging chips and image processing compared to the human retina and visual cortex. The most sophisticated image stacking and processing can also come built right in. The result is decent deep-sky imaging from shockingly small, low-priced units. The image may be viewable on your phone or computer as it builds up in real time. Some can directly enable contributions to citizen-science projects.

Smartscopes are changing the hobby at the entry level. For more on this revolution see Richard Wright's "The Rise of the Smart Telescopes" in the November 2025 Sky & Telescope. And read the magazine's review of this especially small one.

If you get a larger, more conventional computerized scope that allows direct visual use, make sure that its drives can be disengaged so you can swing it around and point it readily by hand when you want to, rather than only slowly by the electric motors (which eat batteries).

---

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; and whatever may be our wishes, our inclinations, or the dictates of our passion, they cannot alter the state of facts and evidence."
            — John Adams, 1770

---

---