This Week’s Sky at a Glance, January 26 – February 3


Moon, Pleiades, Hyades on Jan. 26 and 27, 2018

The Moon visits the Pleiades and the Hyades as it crosses Taurus after first quarter.

Friday, January 26

• The waxing gibbous Moon, two days past first quarter, shines to the right of Aldebaran and lower left of the Pleiades this evening, as shown here (for the middle of North America).

• Later, the Moon's dark limb occults Aldebaran as seen from far northwestern North America during the early-morning hours of Saturday; map and timetables.

Saturday, January 27

• After dark you'll find the Great Square of Pegasus sinking in the west, tipped onto one corner. Meanwhile the Big Dipper is creeping up in the north-northeast, tipped up on its handle.

Sunday, January 28

• As soon as it's fully dark, spot the big, equilateral Winter Triangle high in the southeast under the Moon. Sirius is its brightest and lowest star. Betelgeuse stands above Sirius by about two fists at arm's length. To the left of their midpoint is Procyon.

And, standing directly above Procyon now (depending on your latitude) is 3rd-magnitude Gomeisa, or Beta Canis Minoris, the only other easy naked-eye star of Canis Minor.

Monday, January 29

• Look left of the Moon this evening for Pollux with Castor over it. Farther to the Moon's lower right is brighter Procyon. Far lower right of Procyon is Sirius, brightest of all.

• Orion, high to the upper right of Sirius, is the brightest of the 88 constellations. But his main pattern is surprisingly small compared to some of his dimmer neighbors. The biggest of these is Eridanus the River to his 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 cowering under Orion's feet, isn't much smaller than he is.

Tuesday, January 30

• Now Pollux and Castor are high above the Moon. Procyon shines to the Moon's left.

Total eclipse of the Moon before or during dawn Wednesday morning the 31st for western North America and Hawaii. Farther east, in the Central and Eastern time zones, the eclipse is still only partial by the time the Moon sets (and the Sun rises). The eclipse will be seen on the evening of the 31st for Australia and eastern Asia local date. For all the details see Make the Most of January’s Total Lunar Eclipse (with map) and The Trifecta Lunar Eclipse.

Wednesday, January 31

• Full Moon (exact at 8:27 a.m. Eastern Standard Time). The Moon this evening shines between Cancer and Leo, well to the upper right of Regulus.

• Before dawn Thursday morning, about 1½ hours before your local sunrise time, Jupiter shines high in the south. Lower left of it by 12° is dimmer Mars, magnitude 1.2. Mars on Thursday morning is passing right between Beta Scorpii above it and the Omega1,2 Scorpii pair just below it. The four of them create an interesting, nearly vertical little line 1.2° tall. Binoculars give a fine view of it.

Lower left of Mars by 8° is Mars-colored Antares.

And if you draw a straight line from Jupiter through Mars and extend it another 30°, you come to Saturn glowing low in the southeast.

Thursday, February 1

• The waning gibbous Moon rises around the very end of twilight. Once the Moon is well up, look for Regulus to its upper right and Algieba farther to the Moon's upper left. These are the brightest two stars in the Sickle of Leo.

• Algol shines at its minimum brightness, magnitude 3.4 instead of its usual 2.3, for a couple hours centered on 11:30 p.m. Eastern Standard Time.

Friday, February 2

• 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, Menkalinan and Capella on high, down to Aldebaran, then to Rigel in Orion's foot, and back to Sirius.

Betelgeuse shines inside the Hexagon, off center.

Saturday, February 3

• 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. "Leo announces spring," goes an old saying. Actually, Leo showing up in the evening announces the cold, messy back half of winter. Come spring, Leo will already be high.


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 guide to astronomy.

Pocket Sky Atlas, 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 above is the Jumbo Edition for easier reading in the night. Larger view. Sample chart.

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, is the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.

You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, or the bigger 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."

This Week's Planet Roundup

Jupiter on Jan. 7, 2018

Jupiter's Great Red Spot is still as prominently orange as it was during last year's observing season. Christopher Go in the Philippines took this image before dawn on January 7th, using a 14-inch scope and video stacking during poor seeing. To simulate the view in the eyepiece of a telescope, squint your eyes and view the screen from a distance. Your amount of squinting can simulate the view in a 3-inch to a 16-inch scope. South is up.

Mercury is lost in the sunrise.

Venus remains hidden deep in the sunset.

Mars and Jupiter (magnitudes +1.2 and –2.0, respectively) rise in the east-southeast in the hours after midnight. They're high in the south by early dawn. Jupiter, the first up, is the brightest point in the pre-dawn sky, shining in dim Libra. Mars glows to Jupiter's lower left in the head of Scorpius. Mars passes Beta Scorpii this week; see the January 31 entry above. Jupiter and Mars are 10° apart on the morning of January 27th, widening to 13° apart by February 3rd.

Lower left of Mars is Mars-colored Antares, almost the same brightness.

Saturn (magnitude +0.5, in Sagittarius) is becoming easy to see low in the southeast around the beginning of dawn, if the air is good and clear. About 45 or 50 minutes before sunrise, look for it 30° lower left of Mars.

Uranus (magnitude 5.8, in Pisces) is still well up in the southwest right after dark.

Neptune (magnitude 7.9, in Aquarius) is sinking away low in the west-southwest after dark. Use our Uranus and Neptune finder charts.


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


"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


"Objective reality exists. Facts are often determinable. Vaccines save lives. Carbon dioxide warms the globe. Bacteria evolve to thwart antibiotics, because evolution. Science and reason are not fake news, not a liberal conspiracy. Civilization's survival depends on our ability, and willingness, to use them."
— Alan MacRobert, your Sky at a Glance editor


"Facts are stubborn things."
— John Adams, 1770


"The most damaging consequences of [the current] Truth Decay include the erosion of civil discourse, political paralysis, alienation and disengagement of individuals from political and civic institutions, and uncertainty over national policy."
RAND Corporation report, January 2018


One thought on “This Week’s Sky at a Glance, January 26 – February 3

  1. Anthony BarreiroAnthony Barreiro

    I wonder if the aphorism that Leo announces Spring comes from the Celtic calendar, where the seasons begin on the cross-quarter days with the equinoxes and solstices marking the seasonal midpoints. If Spring begins at Imbolc on February 2, then what you’re calling the cold, messy, back half of Winter would be considered the rich, fertile front half of Spring.

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