This Week's Sky at a Glance, February 25 – March 5

FRIDAY, FEBRUARY 25

■ After dark in late winter, five carnivore constellations are rising upright in a ragged 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. They 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 slithering up the southeast, Canis Minor the Little Dog higher in the south-southeast, and bright Canis Major the Big Dog in the south.

■ With the Moon not yet brightening the evening sky, and the ecliptic tilting high upward from the western horizon at nightfall, this is a fine week to look for the zodiacal light if you live in the world's mid-northern latitudes. From a clear, clean, dark site, look west at the very end of twilight for a vague but huge, tall pyramid of pearly light. It's rather narrow, tilted to the left, and aligned along the constellations of the zodiac. The centerline of the zodiacal light is exactly aligned on the ecliptic itself.

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

SATURDAY, FEBRUARY 26

■ Just a few degrees under the tail of Canis Major, binoculars can reveal the very loose, scattered star clusters Collinder 140 and Collinder 132. They look like hardly more than slight enhancements of the star field, a degree or so across. In each case their brightest few stars are 5th and 6th magnitude. You can nail their identification using the chart with Matt Wedel's Binocular Highlight column in the March Sky & Telescope, page 43.

These are real clusters, not just slight apparent bunchings of random stars at a variety of distances. "Collinder 140 lies about 1,300 light-years away," writes Wedel, "and Collinder 132 is a few hundred light-years farther out." Both are part of the Milky Way's local Orion Spur, of which we are a part.

■ Going deeper: Certain deep-sky objects come with secrets in or near them. With the evening sky still dark and moonless, get out your sky atlas and telescope for a go at Bob King's eight Hidden Gems in Common Deep-Sky Objects currently up in view.

SUNDAY, FEBRUARY 27

■ 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° directly south of Sirius (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 gray haze, very faintly speckled if your sky is good and dark? That's the open star cluster M41, about 2,200 light-years away and much richer and more compact than the two discussed above. Its total magnitude adds up to 5.0.

MONDAY, FEBRUARY 28

■ It's not spring for another three weeks. But the Spring Star Arcturus seems eager to jump into view. It rises above the east-northeast horizon only about an hour after full dark 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 is high up and dominates the eastern sky.

TUESDAY, MARCH 1

■ With the Moon gone and Monoceros walking across the south behind Orion, now's a fine time to trace out the Unicorn's big, dim stick figure. Use the constellation chart in the center of the February or March Sky & Telescope.

Many binocular starwatchers know about its distinctive star cluster NGC 2244, a boxy little rectangular pattern in the center of the vastly fainter Rosette Nebula. It's right about where the Unicorn's eye might be in his triangular head. The brightest stars of the pattern are 6th and 7th magnitude. Find then 10° to the celestial east-southeast of Betelgeuse. The elongated rectangle currently stands upright.

If you've got big binoculars or a small telescope, try next for the larger but fainter Christmas Tree Cluster, NGC 2264, at 15 Monocerotis: the 5th-magnitude star marking the tip of the Unicorn's horn above the back of its head. The stars outlining the Christmas Tree are 7th and 8th magnitude. The tree currently hangs downward from its base, marked by 15 Mon. See Matt Wedel's Binocular Highlight column and map in the February Sky & Telescope, page 43.

■ A dawn challenge: As the sky brightens a mere 20 minutes or so before sunrise Wednesday morning, use large binoculars or a wide-field telescope to scan just above the east-southeast horizon for Mercury and Saturn in conjunction, 0.7° apart. Look for them a good 22° lower left of bright Venus. Saturn is the fainter one, to Mercury's upper left. You'll need a very flat, open horizon in that direction.

WEDNESDAY, MARCH 2

■ Want to try for Sirius B, the notoriously difficult white dwarf companion of Sirius? Sirius A and B now appear their farthest apart in their 50-year orbit, separated by 11.3 arcseconds (they're exactly farthest apart next year, if you're picky), and they'll remain very nearly as wide for the next few years before they start closing up again.

You'll want at least an 8- or 10-inch scope and a night of really excellent seeing. Keep checking night after night; top-notch seeing makes all the difference for spotting Sirius B. The time to try is when Sirius stands at its very highest, as it does now in early evening. 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 of the foil crossing the center of the field. Hide blinding Sirius A just behind the strip's eastern edge.

■ New Moon (exact at 12:35 p.m. Eastern Standard Time).

THURSDAY, MARCH 3

■ It's March, so Orion stands a little west of due south now. Under Orion's feet, and to the right of Sirius, hides Lepus the Hare. Like Canis Major, this is a constellation with a connect-the-dots that really looks like what it's supposed to be. He's a crouching bunny, with his nose pointing lower right, his faint ears extending up toward Rigel (Orion's brighter foot), and his body bunched to the left. His brightest two stars, 3rd-magnitude Alpha and Beta Leporis, form the back and front of his neck, respectively.

■ And what's under Lepus? Columba the Dove, a dim scattering. See the constellation chart in the center of the February Sky & Telescope. Its brightest star, Alpha Columbae or Phact, is magnitude 2.6. To find it, draw a line from Rigel through Beta Leporis and extend it the same distance straight on.

■ Tonight Algol should be at minimum light, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 12:17 a.m. EST; 9:17 p.m. PST. Algol takes several more hours to fade and to rebrighten.

FRIDAY, MARCH 4

■ February was Orion's month to stand at his highest in the south in early evening. Now March pushes him westward and brings his dog to center stage on the meridian: Canis Major, sporting 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 living at mid-northern latitudes.

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

SATURDAY, MARCH 5

■ Look east after dusk this week for 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. The sickle includes Algieba, second in brightness to Regulus by only a small amount.

 

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This Week's Planet Roundup

Venus and much fainter Mars continue in the early dawn as shown at the top of this page. Look southeast.

Mercury is much lower in the dawn, some 22° to Venus's lower left. And now Saturn emerges from the sunrise glare. It comes to conjunction with Mercury on the morning of March 2nd, when they're only 0.7° apart. Mercury that morning is the brighter one; Saturn glimmers to its upper left.

Jupiter has sunk out of sight in the sunset.

Uranus (magnitude 5.8, in Aries) is in the west right after dark. Finder chart.

Neptune has followed Jupiter down into the sunset glow.

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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 (also called UT, UTC, GMT, or Z time) minus 5 hours.

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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 magazine of 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 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. 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 magnitude 9.75). And be sure to 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 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. 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."

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

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"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