This Week’s Sky at a Glance, February 12 – 20 – Sky & Telescope


■ Orion stands his highest within the south by about Eight p.m., wanting smaller than you in all probability bear in mind him showing early within the winter when he was low. You’re seeing the “Moon illusion” impact. Constellations, not simply the Moon, look greater after they’re low.

Under Orion’s toes, and to the appropriate of Sirius now, hides Lepus the Hare. This is a constellation with a join-the-dots that basically appears like what it is alleged to be. He’s a crouching bunny, along with his nostril pointing decrease proper, his faint ears extending up towards Rigel (Orion’s brighter foot), and his physique bunched to the left. His brightest two stars, third-magnitude Alpha and Beta Leporis, kind the front and back of his neck.


■ By 9 p.m. or so, the Big Dipper stands on its deal with within the northeast. In the northwest, Cassiopeia additionally stands on finish (its brighter finish) at about the identical top. Between them is Polaris.


■ Have you ever carefully in contrast the colours of Betelgeuse, Aldebaran, and Mars? This winter you could have a good probability to take action! Can you detect any distinction of their colours at all?Betelgeuse is the highest-left nook of Orion’s shiny sample, excessive within the south in early night. Aldebaran is 2 fists at arm’s size to the appropriate of Betelgeuse. Mars is now the identical distance decrease proper of Aldebaran.

I am unable to see any colour distinction between the 2 stars. Yet Aldebaran, spectral kind K5 III, is commonly referred to as an “orange” big, whereas Betelgeuse, spectral kind M1-M2 Ia, is often referred to as a “red” supergiant. Their temperatures are certainly barely totally different: 3,900 Kelvin and three,600 Kelvin, respectively.

Mars, in the meantime, appears to me appears very barely extra yellowish than both star.

A complication: Betelgeuse is brighter than the opposite two, and to the human eye, the colours of shiny objects seem, falsely, to be desaturated: tending paler (whiter) than they are surely. You can get a barely higher learn on the colours of shiny stars by defocusing them a bit to unfold their mild over a bigger space of your retina.


■ Right after evening is absolutely darkish this week, the W of Cassiopeia shines excessive within the northwest, standing virtually on finish. The brightest star between Cassiopeia and the zenith, at that point for the world’s mid-northern latitudes, is Alpha Persei (Mirfak). Around and higher left of it’s the Alpha Persei Cluster: a giant, very free swarm of modestly shiny stars concerning the dimension of your thumbtip at arm’s size. They present finest in binoculars.Alpha Per is a true member of the cluster. It and the remainder of the group are about 560 mild-years away.


■ Sirius the Dog Star blazes excessive within the southeast after dinnertime, the brightest star of Canis Major. Spot it decrease left of Orion. In a darkish sky with plenty of stars seen, the celebs of Canis Major may be related to kind a convincing canine profile. He’s at present prancing on his hind legs; he wears Sirius on his chest.

But via the sunshine air pollution the place most of us stay, solely his 5 brightest stars are simply seen. These kind a quick-dealt with meat cleaver. Sirius is the cleaver’s prime again nook, its blade faces proper, and its stubby deal with is all the way down to the decrease left.


■ The Moon shines under Mars this night (by about 12° for North America). Look to the Moon’s proper by the identical distance, and there are the brightest stars of Aries, magnitudes 2.0, 2.6, and three.9 from prime to backside.

Above Mars by a lesser distance are the Pleiades.


■ Mars shines over the Moon as the celebs come out this night, as proven under. Later within the night the scene rotates clockwise with respect to your horizon, placing Mars to the Moon’s higher proper.

They seem solely about 4° aside throughout night for North America. In bodily distance, although, Mars is 515 instances farther away: 11 mild-minutes in comparison with the Moon’s 1.Three mild-seconds. And, Mars is twice as giant in diameter because the Moon.

The Moon, waxing via first quarter, passes related-wanting Mars and Aldebaran excessive within the night sky.FRIDAY, FEBRUARY 19

■ First-quarter Moon (precisely so at 1:47 p.m. EST). The Moon shines between Aldebaran and the Pleiades excessive within the night, as proven above.


■ Now spot Aldebaran under the Moon, as proven above.

■ Have you ever seen Canopus, the second-brightest star after Sirius? In one of many attention-grabbing coincidences identified to devoted skywatchers, Canopus lies virtually due south of Sirius: by 36°. That’s far sufficient south that it by no means seems above your horizon except you are under latitude 37° N (southern Virginia, southern Missouri, central California). And there, you may want a very flat south horizon. Canopus crosses the south level on the horizon simply 21 minutes earlier than Sirius does.

When to look? Canopus is due south when Beta Canis Majoris — Murzim the Announcer, the star about three finger-widths to the appropriate of Sirius — is at its highest due south over your panorama. That’s in all probability someday between Eight and 9 p.m. now, relying on how far east or west you reside in your time zone. Look straight down from Murzim then.


This Week’s Planet Roundup

Mercury, Venus, Jupiter, and Saturn are very deep within the glow of dawn. Venus this week sinks under any probability of recognizing, however the different three are getting a little larger daily. Mercury remains to be method too faint, however you may need a probability at Saturn and decrease however brighter Jupiter. You’ll want binoculars or ideally a huge-area telescope. The diagram under units the scene on the 14th; it is for 20 minutes earlier than dawn at 40° north latitude. Good luck!

Four of the 5 bare-eye planets are grouped low shortly earlier than dawn, the place they might all defy statement. Mars (magnitude +0.7, in japanese Aries) continues to fade. It shines pale yellow-orange excessive within the west-southwest proper after darkish, beneath the Pleiades. Left of the Pleiades shines Aldebaran, basically Mars’s twin now in brightness in addition to colour. In a telescope Mars is barely 7 arcseconds huge, however at least your scope ought to present its gibbous form.

At Mars itself it is a busy time for arriving spacecraft. The United Emirates’ Hope craft and China’s Tianwen-1 braked into Mars orbit simply a few days in the past. NASA’s Perseverance rover ought to land on February 18th.

Why are the missions bunched collectively? Because the minimal-power switch orbit to get from Earth to Mars turns into accessible solely when the 2 planets prepare themselves a specific method with respect to one another each 2.14 years. Dedicated observers will acknowledge this as Mars’s synodic interval — the identical as its common time from one opposition to the subsequent.

Uranus (magnitude 5.8, in western Aries) is roughly 15° under Mars in early night. In binoculars Uranus is a little pinpoint “star.” But with an obvious diameter of three.5 arcseconds, it is a tiny, fuzzy ball at excessive energy in even a pretty smallish telescope with sharp optics — throughout spells of excellent seeing. Finder chart (with out Mars).

Neptune is misplaced in night twilight.

All descriptions that relate to your horizon — together with the phrases up, down, proper, and left — are written for the world’s mid-northern latitudes. Descriptions that additionally rely on longitude (primarily Moon positions) are for North America.

Eastern Standard Time, EST, is Universal Time minus 5 hours. (Universal Time is also called UT, UTC, GMT, or Z time. For extra see Time and the Amateur Astronomer.)

Want to develop into a higher astronomer? Learn your method across the constellations. They’re the important thing to finding all the pieces fainter and deeper to hunt with binoculars or a telescope.

This is an outside nature interest. For a simple-to-use constellation information overlaying the entire night sky, use the massive month-to-month map within the heart of every problem of Sky & Telescope, the important journal of astronomy.

Once you get a telescope, to place it to good use you may want a detailed, giant-scale sky atlas (set of charts). The primary customary is the Pocket Sky Atlas (in both the unique or Jumbo Edition), which exhibits stars to magnitude 7.6.

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and lots of of telescopic galaxies, star clusters, and nebulae amongst them. Shown right here is the Jumbo Edition, which is in exhausting covers and enlarged for simpler studying open air at evening. Sample charts. More concerning the present editions.Next up is the bigger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; practically thrice as many. The subsequent up, as soon as you already know your method round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to magnitude 9.75). And you should definitely learn the way to use sky charts with a telescope.

You’ll additionally need a good deep-sky guidebook, corresponding to Sky Atlas 2000.0 Companion by Strong and Sinnott, or the larger (and illustrated) Night Sky Observer’s Guide by Kepple and Sanner.

Can a computerized telescope change charts? Not for newbies, I do not suppose, and never on mounts and tripods which can be lower than prime-high quality mechanically, that means heavy and costly. And as Terence Dickinson and Alan Dyer say of 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.”

Audio sky tour. Out beneath the night sky with yourearbuds in place, take heed to Kelly Beatty’s monthlypodcast tour of the heavens above. It’s free.

“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.”            — John Adams, 1770


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