This Week's Sky at a Glance, February 2 – 11

FRIDAY, FEBRUARY 2

■ Jupiter is three months past its November 2nd opposition, so it's traveling eastward again against the background stars ("direct motion" as opposed to retrograde). Once the night is fully dark, notice the curved line that Jupiter makes with Alpha Arietis and Alpha Trianguli to the upper right of it, as shown below. That line was nearly straight at the beginning of the year, when Jupiter was at its stationary point. Watch the line grow more bent as Jupiter continues eastward against the stars through the rest of the winter.

■ Last-quarter Moon (exactly so at 6:18 p.m. EST). The Moon rises in the east-southeast around 1 a.m. Saturday morning. It's below Spica, and it's three times that far to the lower right of Arcturus.

SATURDAY, FEBRUARY 3

■ Sirius the Dog Star blazes well up in the southeast by midevening. It's the brightest star of Canis Major. In a dark sky where lots of stars are visible, the constellation's points can be connected to make a convincing dog seen in profile. He's currently standing on his hind legs, facing right. Sirius is on his chest like a dogtag, to the right or lower right of his faint triangular head.

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

■ On Saturday morning the 4th the waning crescent Moon rises around 2 or 3 a.m., lighting the head of Scorpius. By early dawn they're high in the south-southeast, as shown below.

SUNDAY, FEBRUARY 4

Today is the center of winter; we cross the midpoint between the December solstice and the March equinox at 10:16 a.m. EST (15:16 UT). That minute is the very bottom of the wheel of the year, astronomically speaking.

In ancient Gaelic cultures this day was Imbolc: one of the four "cross-quarter" days between the solstices and the equinoxes. The others were May Eve, Lammas, and Halloween, but since then our calendar has shifted a bit from the cross-quarter points.

Groundhog Day (like its German weather-predicting predecessor, Badger Day) was originally the winter cross-quarter day. But now Groundhog Day is considered to be fixed as February 2nd, avoiding the need for yearly adjustments.

Sadly, records since 1887 show that the famous Punxsutawney Phil's weather-prediction record has actually been worse than random.

MONDAY, FEBRUARY 5

■ Soon after dark, face east and crane your neck to look almost straight up. Or lie on your back with your feet to the east and look overhead.

That bright star there is Capella, the Goat Star. Upper right of it, by a couple of finger-widths at arm's length, is a small, narrow triangle of 3rd and 4th magnitude stars known as "The Kids." Though they're not exactly eye-grabbing, they form a never-forgotten asterism with Capella.

TUESDAY, FEBRUARY 6

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

Well 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 topmost outline. 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 with them through light pollution.

■ For Easterners this evening, Io transits Jupiter's face from 6:11 p.m. EST to 8:22 p.m. EST. The sky may still be too bright to see Io entering, but you can watch it leaving.

Io's tiny black shadow follows behind, crossing Jupiter from 7:31 to 9:40 p.m. EST.

■ Dawn challenge: In the dawn of Wednesday morning the 7th, Venus and the very thin waning Moon are low in the southeast. Much more challenging will be fainter Mars and Mercury. They're to Venus's lower left, as shown below. You'll want a flat horizon and optical aid! Good luck.

WEDNESDAY, FEBRUARY 7

■ Orion is the brightest of the 88 constellations, but despite its brightness and fame, its main pattern is surprisingly small compared to some of its dimmer neighbors. The biggest of these is Eridanus the River to its west, enormous but hard to trace. Dimmer Fornax the Furnace, to Eridanus's lower right, is almost as big as Orion! Even the main pattern of Lepus, the Hare crouched under the Hunter's feet, isn't much smaller than he is.

Do you know the constellation down below Lepus? It's a tough one: Columba the Dove, faint, sprawly, and to my eye not a bit dove-like. 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 (the front of the bunny's neck) and extend it an equal distance straight on.

THURSDAY, FEBRUARY 8

■ Have you ever closely compared the colors of Betelgeuse and Aldebaran? Can you detect any difference in their colors at all? I can't. 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: looking 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.

FRIDAY, FEBRUARY 9

■ After it’s good and dark, look due east, not very high, for twinkly Regulus. Extending upper left from it is the Sickle of Leo, a backward question mark. It's about as long as a fist and a half at arm's length. "Leo announces spring," goes an old saying. Actually, Leo showing up in the evening announces the cold, wet, sloppy back half of winter. Come spring, Leo will already be high.

■ New Moon (exact at 6:59 p.m. EST).

SATURDAY, FEBRUARY 10

■ Binocular observers often check in on the 5th-magnitude open cluster M41 just 4° south of Sirius. But how many then look the other way from Sirius for 6th-magnitude M50? It's 10° north-northeast from Sirius, dimmer, smaller and more subtle than M41. Find it by sweeping first to Omicron Canis Majoris, the 4th-magnitude pointy nose of the Big Dog's stick figure, then on again nearly as far in the same direction. It's not exactly easy, but it's there.

M50 really is the smaller and fainter of the two. Both clusters are at nearly the same distances from us: 2,500 light-years for M41 and 2,900 for M50.

For more finding help see Matt Wedel's Binocular Highlight column, with chart, in the February Sky & Telescope, page 43. With big enough binoculars you can also try for the asterism "Pakan's 3" that he plots nearby.

SUNDAY, FEBRUARY 11

■ It's not a big hop from a red supergiant, Betelgeuse, to a red dwarf nearby. Have you ever seen a red dwarf star at all? These are the most common stars in space, but they're so intrinsically dim that not one is among the 6,000 stars visible to the naked eye on even the darkest nights. One of the nearest and brightest red dwarfs lies just 3° west of Procyon, which is nicely placed left of Betelgeuse. The shy little glimmerer is Luyten's Star, also known as GJ 273, and at visual magnitude 9.9 it's in range of many small telescopes. Use the finder charts with Bob King's article Catch Luyten's Star.

This humble object is very close to us as stars go, 12.3 light-years away compared to Betelgeuse's 650. So by no surprise it's also a high proper motion star; it creeps across its celestial backdrop by 3.7 arcseconds per year. This means that a careful visual telescope user might detect its motion in as little as about 3 years, writes King, "depending on its proximity to field stars and the making and breaking of distinctive alignments with other stars." He suggests, "Make an initial observation, note the position in a sketch, map or photo, and then return a couple years later. Hey, no hurry."

To locate and identify Luyten's Star with King's charts you'll need to be good at telescopic star-hopping. This is an essential skill for any telescope user to develop to not get lost when hunting in space. See How to Use a Star Chart with a Telescope, and expect a certain amount of frustration at first. Everyone goes through this. Don't give up.

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This Week's Planet Roundup

Mercury, magnitude –0.3, is virtually out of sight very low in the glow of sunrise.

Venus, magnitude –3.9, shines in the low southeast during dawn. It gets a little lower every morning.

Mars, only magnitude +1.3, remains deep in the sunrise.

Jupiter, magnitude –2.3 in Aries, is that bright white dot very high in the south-southwest at nightfall, and lower in the southwest later. It sets by midnight. In a telescope Jupiter has shrunk to only 39 arcseconds wide.

Saturn, magnitude +1.0 in Aquarius, glimmers very low in the west-southwest in twilight. It sets barely after twilight's end. Good luck.

Uranus, magnitude 5.7 in Aries, remains lurking in the darkness 11° east (upper left) of Jupiter during evening. In a telescope at high power Uranus is a tiny but distinctly nonstellar ball, 3.7 arcseconds in diameter. Locate and identify it using the finder charts in the November Sky & Telescope, pages 48-49.

Neptune, magnitude 7.9, is low in the west-southwest right after dark.

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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 minus 5 hours. UT is also known as UTC, GMT, or Z time.

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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 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.

Once you get a telescope, to put it to good use you'll need 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), which shows all 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 mag 9.75). And 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 computerized telescopes replace charts? Not for beginners I don't think, especially not on mounts and tripods that are less than top-quality mechanically. Unless, that is, you prefer spending your time getting finicky technology to work rather than learning the sky. 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."

If you do get a computerized scope, make sure the drives can be disengaged so you can swing it around and point it readily by hand rather than only slowly by the electric motors.

However, finding a faint telescopic object the old-fashioned way with charts isn't simple either. Learn the tricks at How to Use a Star Chart with a Telescope. 

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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 naked-eye 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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