This Week’s Sky at a Glance, January 19 – 27

 

Betelgeuse in Orion's shoulder stands straight over Sirius at some particular time these evenings — but when does it happen for your particular site? (To make the brightest stars show especially large in this image, legendary sky photographer Akira Fujii stretched a women's nylon stocking over his camera lens as a diffuser.)

Friday, January 19

• Sirius twinkles brightly below Orion in the southeast. Sometime around 8 p.m., depending on your location, Sirius shines precisely below fiery Betelgeuse in Orion's shoulder, as captured at right. How accurately can you time this event for your location, perhaps using a plumb bob or the vertical edge of a building?

Of the two, Sirius leads early in the evening, and Betelgeuse leads later. Welcome to pre-telescopic astronomy.

• The Moon is still just a thin waxing crescent, and in any case it sets pretty soon after dark. So: is your sky dark enough for you to see the winter Milky Way? The Milky Way runs up from Canis Major low in the southeast, then between Orion and Gemini, through Auriga and Perseus almost overhead, and down through Cassiopeia, Cepheus, and Cygnus to the northwest horizon. The Milky Way goes right across your zenith around 9 p.m. (depending on your location).

Saturday, January 20

• Zero-magnitude Capella high overhead, and equally bright Rigel in Orion's foot, are at almost the same right ascension. This means they cross your sky’s meridian at almost exactly the same time: around 9 p.m., depending on how far east or west you live in your time zone. (Capella goes exactly through your zenith if you're at latitude 46° north: Portland, Oregon; Montreal; central France.)

So whenever Capella passes its very highest, Rigel always marks true south over your landscape, and vice versa.

Sunday, January 21

• The waxing crescent Moon remains up in the west-southwest after dark now. Right after dusk, look to the Moon's left (by about two fists at arm's length) for orange Beta Ceti, 2nd magnitude. That's about as bright as the stars of the Great Square of Pegasus — which you'll find balancing on one corner a little farther to the Moon's upper right.

Monday, January 22

• Orion is now high in the southeast right after dark, and he's highest due south around 10 p.m.  Orion is the brightest of the 88 constellations, but his main pattern is surprisingly small compared to some of his dimmer neighbors. The biggest of these is Eridanus the River to his west, enormous but hard to trace. Dimmer Fornax the Furnace, to Eridanus's lower right, is almost as big as Orion! Even the main pattern of Lepus, the Hare cowering under Orion's feet, isn't much smaller than he is.

Tuesday, January 23

• Face east after dark and look very high for brilliant Capella, the Goat Star. To the right of it, by a couple of finger-widths at arm's length, is a small, narrow triangle of 3rd and 4th magnitude stars known as "the Kids." Though they're not exactly eye-grabbing, they form a never-forgotten asterism with Capella.

Around 9 p.m. they all pass straight overhead (for skywatchers at mid-northern latitudes).

Wednesday, January 24

• First-quarter Moon (exact at 5:20 p.m. EST). The Moon shines next to the dim Head of Cetus; look for Alpha Ceti (Menkar), magnitude 2.5 and tinted orange, about 10° to the Moon's left soon after dark (for North America).

A similar distance below the Moon, and a bit left, is Mira, Omicron Ceti, the prototype red long-period variable star. Mira is at its peak brightness this week, about magnitude 3.5. See Bob King's article Mira Makes January Nights “Wonderful”, with sky chart.

Thursday, January 25

• Now Menkar shines about 10° below the Moon by mid-evening. And you'll find the Pleiades about half again that far above the Moon.

Moon, Pleiades, Hyades on Jan. 26 and 27, 2018

The Moon visits the Pleiades and the Hyades as it crosses Taurus after first quarter.

Friday, January 26

• The Moon, two days past first quarter, shines to the right of Aldebaran and lower left of the Pleiades this evening, as shown here (for the middle of North America).

• Later, the Moon's dark limb occults Aldebaran as seen from far northwestern North America during the early-morning hours of Saturday. Map and timetables.

Saturday, January 27

• After dark the Great Square of Pegasus is sinking in the west, tipped onto one corner. Meanwhile the Big Dipper is creeping up in the north-northeast, tipped up on its handle.

• Start planning for the total lunar eclipse that will come on the morning of January 31st for western North America and Hawaii. The eclipse happens on the evening of the 31st for Australia and eastern Asia local date. See the January Sky & Telescope, page 48.

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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, and hundreds of telescopic galaxies, star clusters, and nebulae among them. Shown above is the Jumbo Edition for easier reading in the night. Larger view. 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, 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 on Jan. 7, 2018

Jupiter's Great Red Spot is still as prominently orange as it was during last year's observing season. Christopher Go in the Philippines took this image before dawn on January 7th, using a 14-inch scope and video stacking during poor seeing. To simulate the view in the eyepiece of a telescope, squint your eyes and view the screen from a distance. Your amount of squinting can simulate the view in a 3-inch to a 16-inch scope. South is up.

Mercury is lost in the glow of sunrise.

Venus remains hidden very deep in the sunset.

Mars and Jupiter (magnitudes +1.3 and –1.9, respectively) rise in the east-southeast around 2 or 3 a.m. and are high in the south-southeast by early dawn. Jupiter, the first up, is the brightest point in the sky. Mars glows to Jupiter's lower left. They're 7° apart on the morning of January 20th, widening to 10° apart by the 27th.

Lower left of Mars, look for Antares and the rest of upper Scorpius.

Saturn (magnitude +0.5) is becoming more easily visible very low in early dawn. About 45 minutes before sunrise, look for it above the southeast horizon a good 43° to the lower left of Jupiter. Don't confuse Saturn with twinkly orange Antares about halfway back toward Jupiter, or twinkly Altair far to the left due east.

Uranus (magnitude 5.8, in Pisces) is still high in the southwest right after dark.

Neptune (magnitude 7.9, in Aquarius) is getting low in the west-southwest right after dark. Use our Uranus and Neptune finder charts online or in the October Sky & Telescope, page 50.

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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 (also called UT, UTC, GMT, or Z time) minus 5 hours.

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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

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"Objective reality exists. Facts are often determinable. Vaccines save lives. Carbon dioxide warms the globe. Bacteria evolve to thwart antibiotics, because evolution. Science and reason are not fake news, not a liberal conspiracy. Civilization's survival depends on our ability, and willingness, to use them."
— Alan MacRobert, your Sky at a Glance editor

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

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"The most damaging consequences of [the current] Truth Decay include the erosion of civil discourse, political paralysis, alienation and disengagement of individuals from political and civic institutions, and uncertainty over national policy."
RAND Corporation report, January 2018


 

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