#astronomy This Week’s Sky at a Look, January 17 – 25

January 17, 2020 - Comment

Friday, Jan. 17 • Final-quarter Moon (actual at 7:58 a.m. on this date EST). By the point the Moon rises tonight round 1 a.m., it is going to have waned barely previous exactly half-lit. It’s going to be on the dim toes of Virgo, with Spica to its higher proper and brilliant Arcturus larger to


Friday, Jan. 17

• Final-quarter Moon (actual at 7:58 a.m. on this date EST). By the point the Moon rises tonight round 1 a.m., it is going to have waned barely previous exactly half-lit. It’s going to be on the dim toes of Virgo, with Spica to its higher proper and brilliant Arcturus larger to its higher left.

To the Edge ... and Beyond

The anticenter of the Milky Manner, the purpose reverse the galactic middle in Sagittarius, lies on the junction of Taurus, Auriga and Gemini close to El Nath (Beta Tauri). Face this level, and summery Sagittarius is immediately behind your head.

Saturday, Jan. 18

• Is your sky darkish sufficient so that you can see the winter Milky Manner? In mid-evening now it runs vertically up and throughout the zenith: from Canis Main low within the southeast, up between Orion and Gemini, by means of Auriga and Perseus nearly straight overhead, and down by means of Cassiopeia, Cepheus, and Cygnus to the northwest horizon.

Sunday, Jan. 19

Algol Star Map

Algol was the primary eclipsing variable star found. Good comparability stars for it are Gamma (γ) Andromedae to Algol’s west, magnitude 2.1, and Epsilon (ε) Persei to its east, magnitude 2.9.

• Algol shines at its minimal brightness, magnitude three.four as a substitute of its ordinary 2.1, for about two hours centered on 7:25 p.m. EST. Algol takes a number of extra hours to rebrighten. At any random time you look up at Algol, you’ve solely a 1-in-30 likelihood of catching it at the least 1 magnitude fainter than regular.

• Simply as daybreak begins on Monday morning, about 90 minutes earlier than your native dawn, look low within the southeast for the waning crescent Moon with Mars and Antares hanging beneath it. Lesser, whiter stars of Scorpius are scattered round them and to their proper.

Monday, Jan. 20

Dimmed Betelgeuse. The purple supergiant Betelgeuse marking Orion’s shoulder has at all times been barely variable, however recently it has been in an unusually low dip: As of January 16th it was round visible magnitude +1.5 as a substitute of its extra typical +zero.5. Its fading appears to have stopped. It is clearly fainter than Aldebaran, magnitude +zero.9, with which it is usually in contrast. Go look! It is a sight you’ve got in all probability by no means seen earlier than and should by no means once more. Learn Bob King’s What’s Up With Betelgeuse?

And no, this doesn’t imply Betelgeuse is about to go supernova, regardless of the overinflated hype going round. Sure, it is nearing the top of its life — however on an astronomical timescale! Anticipate to attend one thing like 100,000 years.

Tuesday, Jan. 21

• Sirius twinkles brightly beneath Orion within the southeast after dinnertime. Round eight p.m., relying in your location, Sirius shines exactly beneath fiery Betelgeuse in Orion’s shoulder. How precisely are you able to time this occasion to your location, maybe utilizing the vertical fringe of a constructing? Of the 2, Sirius leads early within the night; Betelgeuse leads later.

• As daybreak brightens on Wednesday morning, spot the slim waning crescent Moon fairly low within the southeast. The bulge of its curve factors decrease left to even-lower Jupiter, 6° or 7° from it (at daybreak for North America). The Moon occults Jupiter for New Zealand and components of Australia round 3h January 23rd UT.

Wednesday, Jan. 22

• The Gemini twins lie on their sides on January evenings, left of Orion. Their head stars, Castor and Pollux, are farthest from Orion, one over the opposite. Castor is the highest one. The Castor determine’s toes are simply left of Orion’s very dim Membership.

Thursday, Jan. 23

• Zero-magnitude Capella, very excessive within the east after darkish, and zero-magnitude Rigel, in Orion’s foot, have nearly the identical proper ascension. This implies they cross your sky’s meridian at nearly precisely the identical time: round 9 p.m. now, relying on how far east or west you reside in your time zone. (Capella goes precisely by means of your zenith in the event you’re at latitude 46°N.) So every time Capella passes highest, Rigel at all times marks true south over your panorama, and vice versa.

Friday, Jan. 24

• Proper after darkish face east and look very excessive for brilliant Capella, the Goat Star. To the fitting of it, by a few finger-widths at arm’s size, is a small, slender triangle of third and 4th magnitude stars generally known as “the Children.” Although they are not precisely eye-grabbing, they kind a never-forgotten asterism with Capella.

• New Moon (actual at four:42 p.m. EST).

Saturday, Jan. 25

• After darkish now the Nice Sq. of Pegasus is declining low within the west, tipped onto one nook. It’s miles to the higher proper of Venus. In the meantime the Massive Dipper is creeping up within the north-northeast, tipped up on its deal with.

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Wish to change into a greater astronomer? Be taught your manner across the constellations. They’re the important thing to finding all the things fainter and deeper to hunt with binoculars or a telescope.

That is an outside nature passion, chilly or not! For an easy-to-use constellation information overlaying the entire night sky, use the large month-to-month map within the middle of every situation of Sky & Telescope, the important information to astronomy.

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The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and a whole lot of telescopic galaxies, star clusters, and nebulae amongst them. Proven above is the Jumbo Version for simpler studying within the night time. Pattern chart.

When you get a telescope, to place it to good use you will want an in depth, large-scale sky atlas (set of charts). The fundamental customary is the Pocket Sky Atlas (in both the unique or Jumbo Version), which reveals stars to magnitude 7.6.

Subsequent up is the bigger and deeper Sky Atlas 2000.zero, plotting stars to magnitude eight.5; practically thrice as many. The following up, as soon as your manner round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) and Uranometria 2000.zero (stars to magnitude 9.75). And skim the best way to use sky charts with a telescope.

You will additionally need a good deep-sky guidebook, equivalent to Sue French’s Deep-Sky Wonders assortment (which incorporates its personal charts), Sky Atlas 2000.zero Companion by Sturdy and Sinnott, or the larger Night time Sky Observer’s Information by Kepple and Sanner.

Can a computerized telescope substitute charts? Not for rookies, I do not assume, and never on mounts and tripods which might be lower than top-quality mechanically (which means heavy and costly). And as Terence Dickinson and Alan Dyer say of their Yard Astronomer’s Information, “A full appreciation of the universe can’t come with out growing the abilities to search out issues within the sky and understanding how the sky works. This information comes solely by spending time beneath the celebs with star maps in hand.”

This Week’s Planet Roundup

Mercury is hidden deep within the glow of sundown.

Venus (magnitude –four.zero, in Aquarius) is that brilliant level shining within the southwest throughout and after twilight. In a telescope Venus nonetheless seems small (14 arcseconds) and gibbous (77% sunlit), however it is going to enlarge in dimension and wane in part because it shines within the night for the subsequent 4 months.

Mars (magnitude +1.5, within the toes of Ophiuchus close to the top of Scorpius) glows modestly within the southeast earlier than and through early daybreak, not very excessive. It is a very tiny four arcseconds in diameter.

Decrease proper or proper of it, by 5° to 7° for North America, twinkles Mars-colored Antares, which at magnitude 1.1 is noticeably brighter than Mars is now (not counting results of atmospheric extinction).

Jupiter (magnitude –1.9, in Sagittarius) could be very low within the glow of dawn. About 30 minutes earlier than sunup, use binoculars to assist scan for it simply above the southeast horizon, far decrease left of faint Mars.

Saturn is out of sight deep within the dawn glow.

Uranus (magnitude 5.eight, in southern Aries) and Neptune (magnitude 7.9, in japanese Aquarius) stand excessive within the south-southwest and low within the southwest, respectively, proper after darkish. Use our finder charts for Uranus and Neptune.

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 upon longitude (primarily Moon positions) are for North America.

Japanese Normal Time (EST) is Common Time (UT, UTC, GMT, or Z time) minus 5 hours.

Audio sky tour. Out beneath the night sky together with your earbuds in place, take heed to Kelly Beatty’s month-to-month podcast tour of the heavens above. It is free.



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