This Week’s Sky at a Glance, February 14 – 22

Share With Your Friends

Betelgeuse remains dim. Orion’s Betelgeuse, always slightly variable, is in an unusually low dip: it’s still about V magnitude +1.6 instead of its more typical +0.5.

Orion is high in the southeast to south these evenings, looking distinctly abnormal to those who know him well, with his two shoulders basically equal. The other shoulder is bluish-white Bellatrix, visual magnitude +1.6, but that’s actually a poor comparison star because of its very different color. As we age our eye lenses yellow, so older people see the world through yellow filters. For instance I’m 68, so I see Bellatrix looking maybe 0.3 magnitude fainter than Betelgeuse even when their measured V magnitudes are the same at +1.6.

And no, this does not mean Betelgeuse is about to go supernova. Not for maybe 100,000 years.

Mercury and Venus in twilight, early Feb. 2020

Venus continues to point the way down to Mercury in twilight. Catch fading Mercury while you still can.

Mars, Jupiter, Saturn in early dawn, Feb. 15, 2020

Three dawn planets are gathering closer together in the southeast. (The visibility of faint points in bright twilight is exaggerated here.)

Moon, Mars, Jupiter, Saturn at dawn, Feb. 18-20, 2020

Now the Moon passes through the dawn planet array. (For clarity, the Moon is shown three times its actual apparent size.)

Mars, Jupiter, Saturn at dawn, Feb. 22, 2020

By week’s end Mars has drawn a bit closer to Jupiter and Saturn. It will walk the line between them from March 20th to 31st.

Friday, Feb. 14

• By 8 or 9 p.m. now, the Big Dipper stands vertically on its handle in the northeast. In the northwest, Cassiopeia also stands on end at about the same height. Between them is Polaris. Winter’s end is in sight.

Saturday, Feb. 15

• Last-quarter Moon (exact at 5:17 p.m. EST.) The Moon rises around 1 or 2 a.m. tonight with the head of Scorpius following up just below it. By the beginning of dawn Sunday they’re nice and high in the south-southeast. At that time Antares is the brightest star under the Moon, and the last to fade out in the oncoming light of day.

Sunday, Feb. 16

• High in the northern sky these evenings, in the seemingly empty wastes between Capella overhead and Polaris due north, sprawls big, very dim Camelopardalis, the Giraffe — perhaps the biggest often-visible constellation you don’t know. Unless you have a really dark sky, you’ll need binoculars to work out its nondescript pattern using the constellation chart in the center of Sky & Telescope — a challenge project that will build your skills for correctly relating what you see in binoculars to what you see, much smaller, on a sky map.

If you’re new at this, start with brighter, easier constellations and save the shy Giraffe until you get
good at it.

Monday, Feb. 17

Occultation of Mars. Early Tuesday morning, the bright limb of the thick waning crescent Moon occults Mars (just 5.2 arcseconds in diameter) for much of North and Central America. Near the East Coast the event happens in daylight with the Moon nicely high in the south. Farther west it happens in morning twilight or pre-dawn darkness. Mars emerges from behind the Moon’s dark limb up to an hour or more later. Map, and local timetables for the disappearance and (starting about halfway down) the reappearance.

Tuesday, Feb. 18

• In early dawn Wednesday, the crescent Moon shines near Jupiter low in the southeast.

Wednesday, Feb. 19

• Right after dark the W of Cassiopeia shines high in the northwest, standing almost on end. The brightest star between Cassiopeia and the zenith, at that time for the world’s mid-northern latitudes, is Alpha Persei (Mirfak). Around and upper left of it is the Perseus OB1 Association: a loose swarm of modestly bright stars about the size of your thumbtip at arm’s length. They show well in binoculars.

A stellar association is a group of stars born around the same place and time but too large and loose to hold together gravitationally as a longer-lasting star cluster.

• in early dawn Thursday, the Moon hangs closely to the lower right of Saturn (for North America). They’re just over the southeast horizon to the lower left of Jupiter. Bring binoculars.

Thursday, Feb. 20

• With the Moon out of the evening sky, this is a fine week to look for the zodiacal light if you live in the mid-northern latitudes — now that the ecliptic tilts high upward from the western horizon at nightfall. From a clear, clean-aired, dark site, look west at the very end of twilight for a vague but huge, tall pyramid of pearly light. It’s tilted to the left, aligning along the constellations of the zodiac. You’re looking at sunlit interplanetary dust orbiting the Sun near the ecliptic plane.

Friday, Feb. 21

• High over Venus after dark are the two brightest stars of Aries, lined up almost vertically.

High above Aries and perhaps a bit left are the Pleiades. Venus is a good 42° away from the Pleiades right now. But watch for the next six weeks as they head straight toward each other. On the evening of April 3rd, Venus will shine just inside the cluster’s edge.

Saturday, Feb. 22

• Have you ever seen Canopus, the second-brightest star after Sirius? In one of the many interesting coincidences that devoted skywatchers know about, Canopus lies almost due south of Sirius: by 36°. That’s far enough south that it never appears above your horizon unless you’re below latitude 37° N (southern Virginia, southern Missouri, central California). And there, you’ll need a very flat south horizon. Canopus crosses the south point on the horizon just 21 minutes before Sirius does.

When to look? Canopus is due south when Beta Canis Majoris — Murzim the Announcer, the star
about three finger-widths to the right of Sirius — is at its highest due south over your
landscape. That’s about 8 p.m. now, depending on how far east or west you are in your time zone. Look
straight down from Murzim then.

• Some telescopic deep-sky objects hold secret surprises in or near them. Get out your telescope and sky atlas for a go at Bob King’s eight Hidden Gems in Common Deep-Sky Objects now in evening view.


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.

Jumbo Pocket Sky Atlas cover

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. 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, are the even larger Interstellarum atlas (stars to magnitude 9.5) and 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

Mercury fades and drops down into the sunset this week. Early in the week it’s still in good view in twilight very low in the west, far lower right of brilliant Venus (about 27°, roughly three fists at arm’s length). On February 14th Mercury is still bright at magnitude +0.2, but by the 18th it’s much less noticeable at +1.6. And by then it’s also getting lower.

Venus (magnitude –4.2, in Pisces) is the big bright “Evening Star” shining in the west during and after dusk. To its right as the stars come out is the Great Square of Pegasus, standing on one corner. Venus doesn’t set until about two hours after the end of twilight.

In a telescope Venus is 17 arcseconds in diameter and gibbous (67% sunlit). It will enlarge in size and wane in phase through winter and much of the spring, passing through dichotomy (half-lit phase) in late March before turning into a dramatic thin crescent in May.

Mars (magnitude +1.2, in Sagittarius) glows in the southeast before and during early dawn. Don’t confuse it with Antares, shining with the same color and brightness some 20° to Mars’s upper right. Mars is still a tiny 5 arcseconds in diameter. But it’s on its way to a fine opposition in October when it will reach 22.6 arcseconds wide.

Jupiter (magnitude –1.9, in Sagittarius) is lower left of Mars in early dawn. No other point there is nearly as bright.

Saturn (magnitude +0.6, also in Sagittarius) is emerging low in the dawn 10° lower left of Jupiter, about a fist at arm’s length. Binoculars will help as the sky brightens.

Uranus (magnitude 5.8, in southwestern Aries) is high in the southwest right after the end of twilight, hiding in the dark some 20° above Venus. Finder chart (without Venus).

Neptune is sinking into the sunset.

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, GMT, or Z time) minus 5 hours.

Audio sky tour. Out under the evening sky with your earbuds in place, listen to Kelly Beatty’s monthly podcast tour of the heavens above. It’s free.

Source link

Share With Your Friends