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EI2GYB > ASTRO 25.02.23 13:41l 123 Lines 9264 Bytes #999 (0) @ WW
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Subj: This Week's Sky at a Glance, February 17 - 26
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This Week's Sky at a Glance, February 17 - 26
By: Alan MacRobert February 17, 2023
FRIDAY, FEBRUARY 17
Ý Jupiter and Venus are closing in on each other in the western evening twilight, as shown in the two scenes below.
They're on their way to an eye-grabbing conjunction on March 1st. That evening they'll be «ø apart and lined up horizontally (seen from the mid-latitudes of North America). Mark your calendar!
SATURDAY, FEBRUARY 18
Ý By 9 p.m. or so, the Big Dipper stands on its handle well up in the northeast. In the northwest, Cassiopeia also stands on end (its brighter end) at about the same height. Between them is Polaris.
Ý A project before moonlight returns later this week: Certain deep-sky objects hold special surprises within 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.
SUNDAY, FEBRUARY 19
Ý Have you ever seen Canopus, the second-brightest star after Sirius? Canopus lies almost due south of Sirius, by 36ø. That's far enough south that it never appears above your horizon unless you're below latitude 37ø 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? You'll know 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. Drop straight down from Murzim then.
MONDAY, FEBRUARY 20
Ý Spot the big, bright, equilateral Winter Triangle in the south-southeast. Sirius is its brightest and lowest star. Betelgeuse is above Sirius by about two fists at arm's length. Left of them shines Procyon.
Ý The Winter Triangle's inside is mostly filled by the front half of Monoceros, the dim Unicorn. It trots across the sky right behind Orion. With the Moon still out of the evening sky, now's a fine time to trace out the Unicorn's big, dim stick figure. Use the constellation chart in the center of the February or March Sky & Telescope.
Many binocular starwatchers know about Monoceros's distinctive star cluster NGC 2244, a boxy little rectangular pattern in the center of the vastly dimmer Rosette Nebula. It's right about where the Unicorn's eye might be in his triangular head. The brightest stars of the box pattern are 6th and 7th magnitude. Find them 10ø to the celestial east-southeast of Betelgeuse. The elongated rectangle currently stands upright.
If you've got big binoculars or a small telescope, try next for the larger but fainter Christmas Tree Cluster, NGC 2264, at 15 Monocerotis: the 5th-magnitude star marking the tip of the Unicorn's horn above the back of his head. The stars outlining the Christmas Tree are only 7th and 8th magnitude. The tree currently hangs downward from its base, marked by 15 Mon. For more see Matt Wedel's Binocular Highlight column and map in the February 2022 issue of Sky & Telescope, page 43.
Ý New Moon (exact at 2:06 a.m. EST on this date).
TUESDAY, FEBRUARY 21
Ý As soon as you first see Venus through the fading twilight this evening, look below it for the very thin waxing crescent Moon, just a day and a half old, as shown below.
WEDNESDAY, FEBRUARY 22
Ý Now the crescent Moon hangs hardly more than 1ø to the right of Jupiter over Venus, as shown above. Think photo opportunity! Get some nice scenery silhouetted in the foreground, zoom in, and prop your phone or camera on something solid so it can take time exposures.
THURSDAY, FEBRUARY 23
Ý Sirius blazes high in the south on the meridian by about 8 or 9 p.m. now. Using binoculars or a scope at low power, examine the spot 4ø south of Sirius (directly below it when on the meridian). Four degrees is somewhat less than the width of a typical binocular's or finderscope's field of view.
Can you see a little patch of speckly gray haze? That's the open star cluster M41, about 2,200 light-years away. Its total magnitude adds up to 5.0.
Sirius, by comparison, is only 8.6 light-years away - and shines some 400 times brighter.
FRIDAY, FEBRUARY 24
Ý After dinnertime at this time of year, five carnivore constellations are rising upright in a row from the northeast to south, as if out of hibernation. They're all seen in profile with their noses pointed up and their feet (if any) to the right. These are Ursa Major the Big Bear in the northeast (with the Big Dipper as its brightest part), Leo the Lion in the east, dim Hydra the Sea Serpent in the southeast, Canis Minor the Little Dog higher in the south-southeast, and bright Canis Major the Big Dog in the south.
SATURDAY, FEBRUARY 25
Ý It's not spring for another 3« weeks, but the Spring Star Arcturus seems eager to thrust itself into view. It rises above the east-northeast horizon around 9 or 10 p.m. now depending on your location.
To see where to watch for it to rise, find the Big Dipper as soon as the stars come out; it's high in the northeast. Follow the curve of its handle down and around to the lower right by a little more than a Dipper-length. That's the spot on the horizon to watch.
Atmospheric extinction keeps it dim when it rises. But by an hour later, Arcturus dominates the low eastern sky.
SUNDAY, FEBRUARY 26
Ý First-quarter Moon (exactly first quarter at 3:06 a.m. tonight EST). This evening the Moon shines between Aldebaran and the Pleiades, as shown below. Mars is off to the Moon's left.
This Week's Planet Roundup
Mercury is hidden deep in the sunrise.
Venus and Jupiter, the two brightest planets, shine boldly in the west-southwest at dusk. Venus is the lower and brighter one; they're magnitudes -3.9 and -2.1, respectively.
They're drawing closer together every day. On Friday the 17th they're 12ø apart and closing fast; a week later on the 24th they're only 5ø apart. They're on their way to a close conjunction on March 1st, when they'll pass just half a degree apart.
Telescopically Venus is a shimmering little gibbous ball, 12 arcseconds in diameter and 87% sunlit. Jupiter is 34 arcseconds wide. That's small for Jupiter; it's nearly on the other side of the solar system from us. Jupiter displays a strikingly dimmer surface brightness in a telescope. That's because it's nearly 7 times farther from the illuminating Sun than Venus is.
Use binoculars to check in on the pinpoint moons of Jupiter, very close to its globe.
Mars, in Taurus, shines very high toward the south right after dusk, almost overhead. It moves lower toward the west as evening grows late. Mars continues to fade, from magnitude +0.2 to +0.3 this week, and it's now only 9 arcseconds wide. That's probably too small to show visual details in most telescopes most nights, aside from its gibbous shape (90% sunlit, see below) and maybe signs of the North Polar Cap.
Spot Aldebaran, magnitude +0.8, below Mars in early evening (by 10ø). Later in the evening, Aldebaran is lower left of Mars.
Saturn is out of sight in conjunction with the Sun.
Uranus, magnitude 5.8 in southern Aries, is still fairly high in the southwest right after dark. It displays a tiny, very slightly blue-greenish gray disk 3.6 arcseconds wide. It a telescope at high power it's definitely non-stellar. See the Uranus finder charts in the November Sky & Telescope, page 49.
Neptune is out of sight in the afterglow of 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 and graphics that also depend on longitude (mainly 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.
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