This Week’s Sky at a Glance, February 10 – 18

The February full Moon is always in (or near) Leo.

The February full Moon is always in or near Leo.

Friday, February 10

• Full Moon (exactly so at 7:33 p.m. EST). A very deep penumbral eclipse of the Moon happens  around sunset or in early evening for most of the Americas. See our article with timetable, February’s Deep Penumbral Lunar Eclipse, and the February Sky & Telescope, page 48.

Look for Regulus 6° or 7° to the Moon's lower left as darkness comes on for North America, as shown here. By midnight, Regulus is directly to the Moon's left.

Saturday, February 11

• Now the Moon shines below Regulus and the Sickle of Leo after dark, as shown here.

Sunday, February 12

• Zenith star: sometime around 7 or 8 p.m. (depending on how far east or west you live in your time zone), zero-magnitude Capella passes closest to your zenith. At almost the same minute, zero-magnitude Rigel, the leading foot of Orion, crosses the meridian due south.

Monday, February 13

• The sky's biggest asterism (informal star pattern) is the Winter Hexagon, filling the southern sky after dinnertime. Start with brilliant Sirius at the Hexagon's bottom. Going clockwise from there, march through Procyon, Pollux and Castor, Menkalinan and Capella nearly overhead, then down to Aldebaran, Rigel in Orion's foot, and back to Sirius. Betelgeuse sparkles inside the Hexagon, off center.

Moon and Jupiter at dawn, Feb. 15 and 16, 2017

The Moon rises with Jupiter late on the nights of February 14th and 15th. By dawn the following mornings, they're on display high in the southwest.

Tuesday, February 14

• The Moon rises around 9 or 10 p.m., with Jupiter following up below it 30 or 40 minutes later. Then only 10 or 15 minutes later, fainter Spica follows Jupiter (look to Jupiter's lower right). By dawn on the 15th the trio has moved over to the high southwest, as shown here.

Wednesday, February 15

• Orion is now high in the southeast at nightfall. Left of Orion's upper part is Gemini, headed by Castor and Pollux at far left. The stick-figure Twins are still lying on their sides. Well below their legs is bright Procyon in little Canis Minor: the doglet whose top is barely visible in profile in a dark sky. He's currently vertical. Procyon marks his rump.

Thursday, February 16

• The inside of the Winter Triangle (Betelgeuse, Sirius, and Procyon) looks pretty empty. But of course it's not. It's full of dim Monoceros, the Unicorn, with the winter Milky Way and telescopic deep-sky sights — as told in Fred Schaaf's "Under The Stars" column in the February Sky & Telescope, page 45.

Friday, February 17

• By 9 p.m. or so, the Big Dipper stands on its handle in the northeast. In the northwest, Cassiopeia also stands on end at about the same height. As spring approaches, the Dipper will rise higher and Cassiopeia will move lower.

Saturday, February 18

• Last-quarter Moon (exact at 2:33 p.m.). Before dawn on Sunday the 19th, look for it in the south-southeast. Antares and upper Scorpius are below and lower right of it. Saturn is farther to its lower left.

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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 guide to astronomy.

Pocket Sky Atlas, jumbo edition

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but it's less than one per square degree on the sky. Also plotted are many hundreds of telescopic galaxies, star clusters, and nebulae. Shown above is the new Jumbo Edition for easier reading in the night. Click image for larger view.

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 new 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 with Red Spot on Jan. 24, 2017

Jupiter on January 24th, imaged by Christopher Go. South is up. Upper left of the Great Red Spot is small, pale-orange Oval BA. The separation between them has increased in recent weeks. In the northern hemisphere, tiny white outbreaks have appeared in the North Equatorial Belt at about the same longitude as the Red Spot. Will they grow?

Mercury has sunk away deep into the glow of sunrise.

Venus dazzles high in the west-southwest during twilight, then lower in the west after dark until setting around 9 p.m.  Venus is at its peak brightness, magnitude –4.8, all February. Upper left of it, spot tiny orange Mars, only 0.4% as bright.

In a telescope Venus is a thick crescent. It's growing larger as it approaches us, now about 37 arcseconds from cusp to cusp. For the rest of the winter Venus will continue to enlarge as its phase wanes down to a super-thin crescent.

Venus in a telescope is least glary when viewed in bright twilight. So get your scope on it as soon as you can see it naked-eye, even before sunset.

Mars (magnitude +1.2) is the faint "star" upper left of Venus. They're 6° to 7° apart this week, starting to widen. In a telescope Mars is just a tiny fuzzblob 5 arcseconds wide.

Vesta, the brightest asteroid, is visible in binoculars at magnitude 6.8 as it moves through Gemini near Pollux and Castor. Article and finder chart.

Jupiter (magnitude –2.2, in Virgo) rises around 10 p.m. and blazes high in the south in the hours before dawn. Spica dangles 3½° lower right of it after they rise, and more directly below it before dawn. Jupiter is creamy white; Spica is an icier shade of white with a trace of blue (once it's fairly high).

In a telescope Jupiter is 40 arcseconds across its equator, on its way to 44 arcseconds in late March and April. It will reach opposition on April 7th.

Jupiter by Juno, Feb. 2, 2017

Jupiter's south polar region, as seen by the Juno orbiter looking down at the pole on February 2nd. Damian Peach assembled this composite from Juno's raw images; click for full-size view. At high latitudes, Jupiter's clouds meander around and fail to form up into belts and zones. But at the very highest latitudes, note the thin polar vortex and the even smaller round polar white spot. The small orange spot on the right-hand limb is Oval BA; compare with the equator-on view from Earth above.

Saturn (magnitude +0.5, in southern Ophiuchus) rises in the early morning hours and stands in the southeast before and during dawn. Redder Antares, magnitude +1.0, twinkles 17° to Saturn's right.

Uranus (magnitude 5.8, in Pisces) is still well up in the southwest right after dark, to the upper left of Venus and Mars. Finder chart showing its background stars.

Neptune is lost in evening twilight.

Jupiter's Great Red Spot, 2003 - 2016

Jupiter's Great Red Spot from 2003 to 2016 (starting from the top), showing its changing color and surroundings. Damian Peach assembled this composite from his consistent images taken across the years. Its brick-red color continues in 2017. North is up.

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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 (UT, UTC, or GMT) minus 5 hours.

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"This adventure is made possible by generations of searchers strictly adhering to a simple set of rules. Test ideas by experiments and observations. Build on those ideas that pass the test. Reject the ones that fail. Follow the evidence wherever it leads, and question everything. Accept these terms, and the cosmos is yours."
— Neil deGrasse Tyson, 2014


"Objective reality exists. Facts are often determinable. Science and reason are no political conspiracy; they are how we discover objective reality. Civilization's survival depends on our ability, and willingness, to do this."
— Alan MacRobert, your Sky at a Glance editor


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


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