Friday, February 3

  • After dinnertime, the waxing gibbous Moon shines high in the southeast. Look to its upper left for bright Capella, to its upper right for Aldebaran, lower right for Orion, and lower left for Gemini including Castor and Pollux.
  • The near-Earth asteroid 433 Eros is still in its closest pass by Earth since 1975. It's magnitude 8.6 all week but starts fading around mid-February. Eros is rapidly heading south; find it moving from Sextans into Hydra using our charts in the January Sky & Telescope, page 52, or online.

    Saturday, February 4

  • The Moon shines in the feet of Gemini this evening, with Castor and Pollux to its left and Orion farther to its right. Well below the Moon sparkles Procyon.

    Sunday, February 5

  • This evening spot Pollux and Castor upper left of the Moon, and Procyon to the Moon's lower right. Farther below the Moon is the much dimmer Head of Hydra asterism.

    Monday, February 6

  • Action at Jupiter! Io reappears out of eclipse from Jupiter's shadow at 7:10 p.m. EST. Then Europa emerges from behind Jupiter's eastern limb at 7:48 p.m. EST. Eleven minutes later, Europa vanishes into eclipse by Jupiter's shadow at 7:59 p.m. EST, to reappear at 10:25 p.m. EST. All these events happen on or just off the planet's eastern (following) limb.

    Meanwhile, Jupiter's Great Red Spot transits the planet's central meridian around 9:32 p.m. EST.

    For timetables of all of Jupiter's satellite doings and Red Spot transits in February, see the February Sky & Telescope, page 53.

    Watch the Moon advance eastward past Regulus and Mars. (This scene is drawn for the middle of North America. European observers: move each Moon symbol a quarter of the way toward the one for the previous date. The blue 10° scale is about the size of your fist held at arm's length. For clarity, the Moon is shown three times actual size.)

    Sky & Telescope diagram


    Tuesday, February 7

  • Full Moon (exact at 4:54 p.m. EST). The Moon shines in western Leo. Look lower left of the Moon for Regulus, as shown here.

    Wednesday, February 8

  • The evening Moon in the eastern sky is to the lower right of Regulus and farther upper right from Mars, as shown here.
  • Saturn is at its stationary point. It now starts moving west against the stars (retrograding), on its way to opposition April 15th.

    Thursday, February 9

  • The waning gibbous Moon rises in mid-evening with Mars and fainter Denebola lined up to its left, as shown here.
  • Uranus is 0.3° south (lower left) of Venus right after dark.

    Friday, February 10

  • In the western sky, bright Jupiter and brighter Venus are 30° apart and closing. Watch the gap between them narrow by 1° per day as they approach their March 13th conjunction.

    Saturday, February 11

  • Algol in Perseus is at its minimum light, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 10:50 p.m. EST (7:50 p.m. PST).

    Want to become a better amateur astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.

    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. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).

    Sky Atlas 2000.0 (the color Deluxe Edition is shown here) plots 81,312 stars to magnitude 8.5. That includes most of the stars that you can see in a good finderscope, and typically one or two stars that will fall within a 50× telescope's field of view wherever you point. About 2,700 deep-sky objects to hunt are plotted among the stars.

    Alan MacRobert


    Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The standards are the little Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger and deeper Sky Atlas 2000.0 (stars to magnitude 8.5); and the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts effectively.

    You'll also want a good deep-sky guidebook, such as Sue French's new Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, the bigger Night Sky Observer's Guide by Kepple and Sanner, or the classic if dated Burnham's Celestial Handbook.

    Can a computerized telescope replace charts? I don't think so — not for beginners, anyway, and especially not on mounts that are less than top-quality mechanically. 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."

    This Week's Planet Roundup

    Venus on Feb. 3, 2012

    Venus is almost always totally featureless to visual observers, but digital stacked-video imaging can sometimes bring out the planet's subtle cloud patterns. These are especially visible in the near ultraviolet (UV). S&T's Sean Walker took these images through color filters on the evening of February 3rd, using the same equipment described for Mars below.

    S&T: Sean Walker


    .

    Mars on Feb. 5-6, 2012

    Mars had grown to 12.2 arcseconds wide by February 5th, when S&T's Sean Walker took this image with a 12.5-inch Newtonian reflector and a DMK 21AU618.AS video camera. South is up. The North Polar Cap is the most obvious feature, but it's already shrinking in the of the Martian northern-hemisphere spring. The subtle bright area just right of center is Elysium, next to dark Hyblaeus. Note the cloud at Olympus Mons on the sunset terminator (at left; celestial west), and the faint cloud haze along the morning limb (right; celestial east).

    S&T: Sean Walker


    Mercury is out of sight in conjunction with the Sun. By the end of February, however, it will be back in view having its best evening apparition of the year, low in the western twilight.

    Venus (magnitude –4.1, in Pisces) is the most brilliant “Evening Star” shining in the southwest during and after dusk. It doesn't set now until a good two hours after dark. Venus will continue to appear a little higher, and stay up a little later, each week all this winter. In a telescope it's still a small gibbous disk, 15 or 16 arcseconds in diameter and 72% sunlit, as seen above. It will reach half-lit phase (dichotomy) in mid- to late March.

    Mars (about magnitude –0.7, at the Leo-Virgo border) rises in the east around 8 p.m., far beneath Regulus and the Sickle of Leo. It's to the right or lower right of 2nd-magnitude Denebola. Mars is brightening rapidly as it approaches Earth. It shines highest in the south, in best telescopic view, around 2 or 3 a.m.

    Jupiter on Jan. 29, 2012

    Jupiter is shrinking as Earth leaves it farther behind, but Christopher Go in the Philippines caught some excellent seeing on January 29th for this extraordinary shot of developments around the Great Red Spot. South is up. Note the white turbulence on the following (right; celestial east) side, and the stark red part of the South Equatorial Belt on the spot's preceding side.The red transitions to white as it squeezes past the spot.

    Christopher Go


    In a telescope Mars has grown to about 12.4 arcseconds wide, close to the 13.9″ it will display when it's nearest to Earth in early March. Mars appears only slightly gibbous now: 97% sunlit.

    Jupiter (magnitude –2.3, still at the Aries-Pisces border) shines high in the south-southwest at dusk, moves lower toward the southwest as evening advances, and sets in the west around 11 or midnight. In a telescope Jupiter has shrunk to 39 or 38 arcseconds wide, as Earth pulls ahead of it in our faster orbit around the Sun.

    Saturn (magnitude +0.6, in Virgo) rises in the east around 11 and is shines highest in the south before dawn. Spica, a bit fainter at magnitude +1.0, is 7° to its right or upper right. Saturn's rings are now tilted a generous 15° from our line of sight. This is the most open the rings have appeared since 2007.

    Saturn on Jan. 21, 2012

    Saturn's rings are tipped a good 15° from our line of sight. South is up. Note the very pale light band in the north temperate region, apparently the remnant of the dramatic, billowing white outbreak that attracted so much attention last year. Christopher Go took this image on January 21, 2012.

    Christopher Go


    Uranus (magnitude 5.9, in Pisces) is in southwest after dark approaching Venus. Uranus will pass 0.3° south (lower left) of Venus on the evening of February 9th.

    Neptune is lost in 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 that also depend on longitude (mainly Moon positions) are for North America. Eastern Standard Time (EST) equals Universal Time (also known as UT, UTC, or GMT) minus 5 hours.

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    • About Alan MacRobert

    Alan M. MacRobert became an avid Sky & Telescope subscriber in 1966 at age 14, joined the editorial staff in 1982, and is now a senior contributing editor, semi-retired. He played a role in practically every part of the magazine and the company's other products for more than a generation, both on the amateur-observing side and the science-reporting side. In 1994 a book collection of his observing how-tos and telescopic sky tours was published as Star Hopping for Backyard Astronomers. He has produced This Week's Sky at a Glance online every week since 1989.

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