This Week's Sky at a Glance, January 30 – February 8

FRIDAY, JANUARY 30

■ The gibbous Moon shines amidst Jupiter, Pollux, and Castor tonight. That's their order of brightness, fr0m brightest to faintest. Can you get a photo that shows all of them well, despite their vast brightness differences? Your difficulty doing this will show what a wide working range of brightnesses ("dynamic range") your eyes have in a given scene, compared to most cameras.

■ Through the moonlight after nightfall, find the Great Square of Pegasus sinking in the west. It's tipped onto one corner with brighter Saturn glowing to its lower left.

Meanwhile the Big Dipper is creeping up in the north-northeast, tipping upward on its handle.

SATURDAY, JANUARY 31

■ Now the Moon shines to the lower left of Jupiter, Pollux, and Castor at dusk. By late evening the Moon is much higher and directly left of the others.

SUNDAY, FEBRUARY 1

■ Full Moon. It's exactly full at 5:09 p.m. EST, so it rises very nearly at sunset (for North America). And for all practical purposes it comes up precisely opposite the setting Sun's location on the horizon.

Darkness tonight will reveal the Sickle of Leo to the Moon's lower left (east), as shown below. By midnight the scene climbs and rotates so that the Moon, very high, will be directly right of the Sickle.

■ Algol should be at its minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 7:36 p.m. EST. It takes several hours after that to fully rebrighten.

MONDAY, FEBRUARY 2

■ The Moon occults Regulus. This evening the Moon, barely past full, will pass in front of the 1st-magnitude star Regulus as seen from most of North America except the far West, Alaska, and the Gulf Coast.

The Moon will be only a day past full and 99% illuminated. Regulus will disappear on the Moon's bright sunlit limb, so you'll need a telescope to separate it from the brilliant lunar glare. The star will reappear up to an hour or more later from behind the very thin crescent of darkness along the Moon's other limb. Again you'll need a telescope.

For a sense of how faint Regulus really is compared to the Moon a day past full, below is part of a frame from Noeleen Lowndes's time lapse of the very similar Regulus occultation on February 11-12, 2017.

Both the star's disappearance and reappearance will happen with the Moon nicely high in the eastern sky for the East Coast, and lower in the east the farther west you are. In in much of the Pacific time zone only the reappearance will happen after moonrise. The West Coast itself misses out entirely.

See map and timetables. The first two tables, with predictions for many locations, are long. The first table gives the times of the star's disappearance behind the Moon's bright edge; the second gives its reappearance out from behind the Moon's thin dark edge. Scroll to be sure you're using the correct table; watch for the new heading as you scroll down. The first two letters are the country name; CA is Canada, not California. The times are in UT (GMT) February 3rd. UT is 5 hours ahead of Eastern Standard Time, 6 hours ahead of CST, 7 ahead of MST, and 8 ahead of PST.

For instance: Use the first table to see that for Minneapolis, Regulus disappears on the Moon's bright limb at 7:43 p.m. February 2nd CST, when the Moon is 11° high in the east (at azimuth 84°). The second table tells that Regulus reappears at 8:42 p.m. CST for Minneapolis, with the Moon now 21° high.

■ Today is the center of winter. We cross the midpoint between the December solstice and the March equinox at 4:11 p.m. EST (21:11 UT). That minute is the exact bottom of the wheel of the year, astronomically speaking.

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

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

TUESDAY, FEBRUARY 3

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

About an hour after dark tonight, the waning gibbous Moon will rise about a fist at arm's length below Regulus.

WEDNESDAY, FEBRUARY 4

■ Jupiter's moon Io starts to cross Jupiter's face at 10:20 p.m. EST (7:20 p.m. PST), followed by its tiny black shadow 37 minutes later. Io exits the other side of Jupiter at 12:36 a.m. EST, again followed by its shadow 37 minutes later.

Meanwhile, Jupiter's Great Red Spot should be on the planet's central meridian around 10:38 p.m. EST.

THURSDAY, FEBRUARY 5

■ Io emerges from eclipse out of Jupiter's shadow at 10:35 p.m. EST. Watch for it to slowly swell into view about a third of a Jupiter-diameter out from Jupiter's east (following) limb.

FRIDAY, FEBRUARY 6

■ The biggest well-known asterism in the sky 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, go upper left to Procyon, then Pollux and Castor (ignoring brilliant Jupiter). Then straight up to 2nd-magnitude Menkalinan and brilliant Capella nearly overhead, then down to Aldebaran high in the south-southwest, then down to Orion's bright foot Rigel, and back to Sirius. Betelgeuse shines inside the Hexagon, off center.

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

Now take the line from Aldebaran to Capella, turn it to go from Aldebaran to Betelgeuse instead, and the Winter Hexagon becomes a variant: the Heavenly G.

SATURDAY, FEBRUARY 7

■ The waning gibbous Moon rises around 11 p.m. with Spica 2° to its upper right. They draw farther apart until Spica is lost in Sunday's brightening dawn.

SUNDAY, FEBRUARY 8

■ The last-quarter Moon rises around 1 a.m. tonight. (It's exactly last quarter at 7:43 a.m. EST Monday morning.) If you're up in the cold hour before the start of dawn, spot Antares and the other stars of upper Scorpius a fist or two to the Moon's lower left, and Spica about twice as far to the Moon's upper right.

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This Week's Planet Roundup

Mercury and Venus are still buried deep in the sunset, but just wait a week or two.

Mars will remain out of sight behind the glare of the Sun all winter and most of the spring.

Jupiter (magnitude –2.6) shines in the middle of Gemini. Jupiter is almost a month past its January 9th opposition, so it shines well up in the east during dusk: the first "star" to show through the fading twilight. Jupiter dominates the higher east after dark. Castor and Pollux remain nearby.

Jupiter is highest in the south, and thus telescopically sharpest, by 9 or 10 p.m. It's still 46 or 45 arcseconds wide. See "Jupiter Rules!" in the January Sky & Telescope, page 48, which includes a map of its dark belts and bright zones.

Saturn (magnitude +1.1, in Pisces) is the brightest dot low in the west-southwest at nightfall, lower left of the Great Square of Pegasus. It sets in the west around 8 or 9 p.m.

In a telescope Saturn's rings are still very thin but gradually opening up, now tilted 2° to our line of sight. The rings' thin black shadow on Saturn's globe is slowly widening too. But the seeing so low will almost certainly be poor.

Uranus (magnitude 5.7, in Taurus 5° south of the Pleiades) is very high in the south these evenings. At high power in a telescope it's a tiny but non-stellar dot, 3.6 arcseconds wide. You'll need a detailed finder chart to identify it among similar-looking faint stars, such as the chart in the November Sky & Telescope, page 49.

Neptune is a telescopic "star" of magnitude 7.9, a dim speck just 2.2 arcseconds wide 2° from low Saturn. For Neptune you'll need an even more detailed finder chart.

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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.

For the attitude every amateur astronomer needs, read Jennifer Willis's Modest Expectations Give Rise to Delight.

Once you get a telescope, to put it to good use you'll want 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. Both show all 30,000 stars to magnitude 7.6, and 1,500 deep-sky targets — star clusters, nebulae, and galaxies — to search out among them.

Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; nearly three times as many, as well as many more deep-sky objects. It's currently out of print, but maybe you can find one used.

The next up, once you know your way around well, are the even larger Interstellarum Deep-Sky Atlas (with 201,000+ stars to magnitude 9.5 and 14,000 deep-sky objects selected to be detectable by eye in very large amateur telescopes), and Uranometria 2000.0 (332,000 stars to mag 9.75, and 10,300 deep-sky objects).

Read How to Use a Star Chart with a Telescope. It applies just as much to electronic charts on your phone or tablet — which many observers find handier and more versatile, if perhaps less well designed, than charts on paper.

You'll also want a good deep-sky guidebook. A beloved old classic is the three-volume Burnham's Celestial Handbook. It was my bedside reading for years. An impressive more modern one is the big Night Sky Observer's Guide set (2+ volumes) by Kepple and Sanner. The pinnacle for total astro-geeks is the new Annals of the Deep Sky series, currently at 11 volumes as it works its way forward through the constellations alphabetically. So far it's up to H.

Can computerized telescopes replace charts? Well, I used to say this:

"Not for beginners, I don't think, unless you prefer spending your time getting finicky technology to work rather than learning how to explore through the sky yourself. 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 and a curious mind.' Without these, 'the sky never becomes a friendly place.' "

Well, things change. The technology has continued to improve and become more user-friendly — particularly with software that can now recognize any star field to determine exactly where the telescope is pointed — finally bypassing all aiming imperfections in the mount, tripod, gears, bearings and other mechanics, or in the user's skill in setting up.

The latest revolution is the rise of small, imaging-only "smartscopes." These take advantage of not only today's pointing technology, but also the vastly better capabilities of imaging chips and processing compared to the human retina and visual cortex. The most sophisticated image stacking and processing can also come built in. The result is decent deep-sky imaging from shockingly small, low-priced units. The image may be viewable on your phone or computer as it builds up in real time. Small smartscopes can enable direct contributions to citizen-science projects.

These are changing the hobby at the entry level. For more on this revolution see Richard Wright's "The Rise of the Smart Telescopes" in the November 2025 Sky & Telescope. And read the magazine's review of this especially small one.

If you get a larger, more conventional computerized scope that allows direct visual use, make sure that its drives can be disengaged so you can swing it around and point it readily by hand when you want to, rather than only slowly by the electric motors (which eat batteries).

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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; and whatever may be our wishes, our inclinations, or the dictates of our passion, they cannot alter the state of facts and evidence."
            — John Adams, 1770

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