This Week’s Sky At a Glance, March 5 – 13 – Sky & Telescope


■ High in the southwestern sky, Mars is passing about 3° left of the Pleiades this evening and tomorrow evening, as shown below.

Mars passes the Pleiades. By next Friday the 12th, it will be 5° to the Pleiades’ upper left. (The blue 10° scale is about the size of your fist at arm’s length.)

■ February was Orion’s month to stand at his at his highest in the south in early evening. Now March pushes him westward and brings his dog, Canis Major sporting Sirius, onto the meridian.

In a moonless dark sky, the stars of Canis Major can be connected to form a nice dog profile, but through a brighter sky only his five brightest stars show well. These form the unmistakable Meat Cleaver. Sirius and Murzim (to its right) are the Cleaver’s wide top end, with Sirius sparkling on its top back corner. Down to Sirius’s lower left is the Cleaver’s other end, including its short handle, formed by the triangle of Adhara, Wezen, and Aludra. The Cleaver is chopping toward lower right.

■ Want to try for Sirius B, the famous white dwarf? Sirius A and B are now at the apparent widest of their 50-year orbit, 11 arcseconds apart, and will remain so for the next several years before they start closing up again. You’ll want at least an 8-inch scope, a night of really excellent seeing (keep checking night after night), Sirius at its very highest like it is now, and 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 with a bit of tape. Looking through the eyepiece, use a pencil point to maneuver the strip into sharp focus. At the scope, hide blinding Sirius A just behind the strip’s edge.

■ Up in early dawn Saturday morning? Spot the waning Moon in the south with, before the sky gets too bright, Antares about 12° to its right (for North America), amid upper Scorpius.


■ With the Moon gone from the evening sky, this is a fine week to look for the zodiacal light if you live in the mid-northern latitudes. At this time of year the ecliptic tilts high upward from the west horizon at nightfall. 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 tilted to the left, aligning along the constellations of the zodiac.

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

■ Also for these moonless nights: Certain deep-sky objects hold secret surprises within or near them. Get out your telescope and sky atlas for a go at Bob King’s eight Hidden Gems in Common Deep-Sky Objects now in evening view.


The brightest asteroid, 4 Vesta, is just past opposition in Leo and shining at a binocular-easy magnitude 5.8. Use the finder chart with the article about Vesta in the March Sky & Telescope, page 48. If you were to swap Vesta in for our Moon, “the asteroid would look like a baby white potato with an apparent diameter of 4.7 arcminutes, about half the width of the Moon’s Mare Imbrium. But Vesta would look spotlight-bright because it’s nearly four times as reflective as our satellite neighbor.”


■ On the traditional divide between the winter and spring sky is the dim constellation Cancer. It’s between Gemini to its west and Leo to its east. Cancer holds something unique: the Beehive Star Cluster, M44, in its middle.

The Beehive shows dimly to the naked eye if you have little or no light pollution. With binoculars it’s easy, even under worse conditions. Look for it a little less than halfway from Pollux in Gemini to Regulus in Leo.

■ “Ken’s Cancer Cascade” may sound like a terrible event at a hospital, but it’s actually a long asterism of a star line, Kemble’s Cascade style, 2° long at the Cancer-Gemini border. See Ken Hewitt-White’s “All Around the Beehive” article, photos, and chart in the March Sky & Telescope, page 54.

■ As dawn brightens on Tuesday and Wednesday mornings, the waning crescent Moon poses with Saturn, Jupiter, and Mercury very low in the southeast. See the second panel in “This Week’s Planet Roundup” below.


■ Bright Sirius, in the south these evenings, is the bottom star of the 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.

■ Using binoculars or a telescope at low power, examine the spot 4° south of Sirius (directly below it when near 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 there? That’s the open star cluster M41, about 2,200 light-years away. Its total magnitude adds up to 5.0, not at all hard in binoculars and obvious in a telescope.

Sirius, by comparison, is only 8.6 light-years away and shines 400 times brighter.


■ By nightfall, the Big Dipper is high in the northeast and beginning to tip left. Look left of its center, by about three fists at arm’s length, for Polaris in the dim Little Dipper. 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 (similar to Polaris in brightness) and below it, fainter Pherkad. Find these two “Guardians of the Pole” to Polaris’s lower right by about a fist and a half at arm’s length.

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


■ Left of Orion and above Sirius is dim Monoceros, the Unicorn. If you’re a binocular observer, maybe you know of the showy star cluster NGC 2244, the long rectangle of a thing in the dim Rosette Nebula in Monoceros’s stick-figure head. But how about subtler, looser NGC 2232 some 10° south if it, just above the Unicorn’s forefoot? See the chart and discussion in Matt Wedel’s Binocular Highlight in the March Sky & Telescope, page 43.


■ Spot Arcturus, the Spring Star, very low in the east-northeast after nightfall and higher in the east later in the evening. 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 (using the combined light of Alpha Cen A and B; they appear as one to the unaided eye).

For northerners who can never see Canopus or Alpha Cen, Arcturus is bested by Sirius alone. However, Vega and Capella are very close on its heels.


■ 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.

But did you know that if you follow the Pointers backward the opposite way, you’ll land in Leo?

Draw a line diagonally across the Dipper’s bowl from where the handle is attached, continue far on, to go to Gemini.

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 come to Capella.

■ New Moon (exact at 5:21 a.m. EST).

Daylight-saving time begins, for most for North America, at 2 a.m. tonight. Clocks spring forward an hour. Tonight there will be no such thing as 2:30 a.m. local civil time.


This Week’s Planet Roundup

Mercury, Jupiter, and Saturn wait for you very low in bright dawn. Jupiter and Saturn are getting a little higher and easier to see each morning, while lower Mercury continues to maintains its altitude and brightness. Look very low in the east-southeast about 30 minutes before sunrise, as shown below. With the sky that bright, bring binoculars.

Mercury is about magnitude +0.1, Saturn is magnitude +0.7, and Jupiter is mag –2.0.

Jupiter and Mercury are coming off their March 5th conjunction, while Saturn looks on. They widen from 1° apart on the morning of Saturday the 6th to 6½° apart on Friday the 12th.

Venus is out of sight in conjunction with the Sun.

Mars (magnitude +1.0, in Taurus) passes the Pleiades early this week, as shown at the top of this page. Look high in the west in early evening. Left of Mars shines Aldebaran, essentially the twin of Mars in brightness now as well as very nearly so in color. Their separation shrinks from 11° to 9° this week. They’ll be passing 7° apart at the turn of spring on March 20th.

In a telescope Mars is a mere 6 arcseconds wide: a tiny bright blob.

Uranus (magnitude 5.8, in western Aries) is far below Mars in early evening. Look for it right after dark before it sinks lower. Finder chart.

Neptune is in conjunction with the Sun.

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

Eastern Standard Time, EST, is Universal Time minus 5 hours. (Universal Time is also known as UT, UTC, GMT, or Z time. For the down-and-dirty details see Time and the Amateur Astronomer.)

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.

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 magnitude 9.75). And be sure to read how to use sky charts with a telescope.

You’ll also want a good deep-sky guidebook, such as Sky Atlas 2000.0 Companion by Strong and Sinnott, or the bigger (and illustrated) Night Sky Observer’s Guide 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.”

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.

“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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