This Week's Sky at a Glance, February 5 – 13

FRIDAY, FEBRUARY 5

■ Before and during early dawn on Saturday morning the 6th, spot the waning crescent Moon in the south-southeast with Antares some 4° or 5° to its lower right, as shown below.

■ High in the northern sky these moonless 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 really dark sky, you'll need binoculars to work out its 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 constellation map.

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

SATURDAY, FEBRUARY 6

■ The sky's biggest asterism (informal star pattern) — at least the biggest that's widely recognized — is the Winter Hexagon. It fills the sky toward the east and south these evenings. Start with brilliant Sirius at its bottom. Going clockwise from there, march up through Procyon, Pollux and Castor, then Menkalinan and Capella on high, down to Aldebaran, then to Rigel in Orion's foot, and back to Sirius. Betelgeuse shines inside the Hexagon, well off center.

The Hexagon is somewhat distended. But if you draw a line through its middle from Capella down to Sirius, the "Hexagon" is fairly symmetric with respect to that axis.

■ Algol should be at its minimum brightness tonight, magnitude 3.4 instead of its usual 2.1, for a couple hours centered 12:46 a.m. EST ( 9:46 p.m. PST). Algol takes several additional hours to fade and to rebrighten.

SUNDAY, FEBRUARY 7

■ Have you ever closely compared the colors of Betelgeuse and Aldebaran? Can you detect any difference in their colors at all? I can't, really. Yet Aldebaran, spectral type K5 III, is often called an "orange" giant, while Betelgeuse, spectral type M1-M2 Ia, is usually called a "red" supergiant. Their temperatures are indeed a bit different: 3,900 Kelvin and 3,600 Kelvin, respectively.

A complication: Betelgeuse is brighter, and to the human eye, the colors of bright objects appear, falsely, to be desaturated: tending paler (whiter) than they really are. You can get a slightly better read on the colors of bright stars by defocusing them a bit, to spread their light over a larger area of your retina.

Compare them both to Mars. Mars is about two fists at arm's length lower right of Aldebaran and slightly fainter. To me, it seems to have a very slightly more yellowish hue than either star.

MONDAY, FEBRUARY 8

■ This being early February, Orion is now high in the south-southeast right after dark. Left of him is Gemini, headed up by Castor and Pollux at far left. The stick-figure Twins are still lying on their sides.

Below their legs is bright Procyon. Standing 4° above Procyon is 3rd-magnitude Gomeisa, Beta Canis Minoris, the only other easy naked-eye star of Canis Minor. The Little Dog is seen in profile, but only his back. Procyon marks his rump, Beta CMi is the back of his neck, and two fainter stars just above that are the top of his head and his nose. Those last two are only 4th and 5th magnitude, respectively. Binoculars help through light pollution.

For more about the Little Dog Star, see Fred Schaaf's "In Praise of Procyon" in the February Sky & Telescope, page 45.

TUESDAY, FEBRUARY 9

■ After it’s good and dark, look due east for twinkly Regulus, not very high. Extending upper left from it is the Sickle of Leo, a backward question mark, outlining the Lion's forequarters. "Leo announces spring," goes an old saying. Actually, Leo showing up after dark announces the cold, clammy, messy back half of winter. Come spring, Leo will already be high.

■ Algol should be at minimum light for a couple hours centered on 9:35 p.m. EST.

WEDNESDAY, FEBRUARY 10

■ A favorite field high overhead these nights is the rich Milky Way area at the dragging foot of the Castor stick figure, one of the Gemini twins. Here lie two 3rd-magnitude red giants and the big, filmy, distended speckle of the open star cluster M35, total magnitude about 5. But there's more: the compact cluster NGC 2129 gathered closely around a pair of 7th- and 8th-magnitude stars; the very loose group Collinder 29 bordered by a little Y asterism; and the deep red stars TV and 6 (or V) Geminorum. See Matt Wedel's Binocular Highlight column, "In the Twins' Toes," in the February Sky & Telescope, page 43, with chart. But a scope will do better than binocs.

THURSDAY, FEBRUARY 11

■ Sirius the Dog Star blazes high in the southeast after dinnertime, the brightest star of Canis Major. In a dark sky with lots of stars visible, the constellation's points can be connected to form a convincing dog profile. He's currently prancing on his hind legs; he wears Sirius on his chest.

But through the light pollution where most of us live, only his five brightest stars are easily visible. These form a short-handled meat cleaver. Sirius is the cleaver's top back corner, its blade faces right, and its stubby handle is down to the lower left.

■ New Moon (exact at 2:06 p.m. EST).

FRIDAY, FEBRUARY 12

■ Orion stands his highest in the south by about 8 p.m., looking smaller than you probably remember him appearing early in the winter when he was low. You're seeing the "Moon illusion" effect. Constellations, not just the Moon, look bigger when they're low.

■ Under Orion's feet, and to the right of Sirius now, 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.

SATURDAY, FEBRUARY 13

■ By 9 p.m. or so, the Big Dipper stands on its handle in the northeast. In the northwest, Cassiopeia also stands on end (its brighter end) at about the same height. Between them is Polaris.

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This Week's Planet Roundup

Mercury, Venus, Jupiter, and Saturn are gone from sight in the glare of the Sun. . . unless you want to try a super-hard challenge using a wide-field telescope maybe 10 minutes before sunrise late in the week. The diagram below sets the scene; it's for 20 minutes before sunrise at 40° north latitude, but clearly you'll need to wait a little longer for the planets to climb a bit while the sky grows even brighter. Jupiter and Venus may be the least hopeless. You can forget Saturn and especially Mercury.

Mars (magnitude +0.5, in Aries) shines pale yellow-orange high in the southwest right after dark. It sets in the west-northwest around 1 a.m. Mars is only 8 or 7 arcseconds wide now, but at least a telescope will show its gibbous shape.

At Mars itself, on the other hand, February is a busy month for arriving spacecraft. The United Emirates' Hope craft will take up high-altitude orbit on February 9th to study the planet's atmosphere. China's Tianwen-1 orbiter, lander and rover will arrive less than a day later. The largest and most ambitious mission is NASA's Perseverance rover, which will land on the 18th to, among other things, collect samples for future return to Earth and launch a miniature reconnaissance helicopter.

Why are the three missions bunched together? Because the minimum-energy transfer orbit to get a craft from Earth to Mars becomes available only when the two planets line up a particular way with respect to each other every 2.14 years. Dedicated Mars observers will recognize this as the synodic period of Mars with respect to Earth — the same as the average time from one opposition to the next. All three missions launched last July.

Uranus (magnitude 5.8, in Aries) is roughly 10° degrees below Mars in early evening. In binoculars Uranus is a little pinpoint "star." But with an apparent diameter of 3.5 arcseconds, it's a tiny, fuzzy ball at high power in even a smallish telescope with sharp optics — during spells of good seeing. Finder chart (without Mars).

Neptune (magnitude 8.0) is sinking out of sight in evening twilight.

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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 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 more see Time and the Amateur Astronomer.)

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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 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."

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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

 

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