Skywatcher's Guide: December 2023 and January 2024

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• Stars and Constellations
• Solar System
• Calendar of Night Sky Events
• Deep Sky
• Frequently Asked Questions

Stars and Constellations

In December, the summer constellations are still visible for the first few hours of the night towards the west.  The Summer Triangle is still fairly high, with Vega heading to the west-northwest, Deneb closest to the zenith, and Altair in the west-southwest.  The center of the Milky Way is now below the horizon, but there is still a good portion of our galaxy we can see streaking high across the sky. The fall sky is now very prominent, getting high in the eastern sky.  The "W" of Cassiopeia is very high in the north-northeast. In the absence of the Big Dipper (part of our spring sky) Cassiopeia can be used to locate the north star: The top (open side) of the "W" faces to the north, so in that direction look for a star about the same brightness as the main stars in Casssiopeia, and that will most likely be Polaris.  Next, the Great Square of Pegasus is nearly in the middle of the sky.  Andromeda is nearby in the northeast, with Perseus just below.  There is also a fairly bright star called Fomalhaut in the south, though its constellation Piscis Austrinus is not easy to distinguish.  Finally, the winter sky is beginning to come up along the eastern horizon.  Taurus the bull is now up in the east with the bright star Aldebaran and the Pleiades (aka the seven sisters or Subaru) star cluster.  Auriga the charioteer is also up in the northeast, with the bright star Capella.

In January, the summer constellations are now very low in the west.  Deneb is the highest point of the Summer Triangle in the northwest, with Vega below near the horizon, and Altair more towards the west.  The Milky Way continues to streak across the sky, though the summer portion is now giving way to the winter portion.  The fall constellations are now right in the middle of the sky.  More of the winter constellations are now up, most notably Orion the hunter in the east below Taurus.  Gemini the twins are also up in the east-northeast just below Auriga.

Interesting Stars Visible in December and January (from 7 to 10 PM)

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Solar System

Mercury is visible near the western horizon after sunset for the first part of December but passes between us and the Sun later in the month.  It will then be visible near the eastern horizon before sunrise for all of January.

Venus is high in the east before sunrise, getting a little lower each morning.

Mars is hidden by the glare of the Sun for most of December but will be visible in the east before sunrise in January.

Jupiter is in Aries and starts the night high in the southeast during December, moving to the south in January.

Saturn is in Aquarius and starts the night high in the south during December, moving to the southwest in January.

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Jupiter Great Red Spot Transits in December and January (from 7 to 10 PM)

Note: The GRS is visible on the disk of Jupiter for 50 minutes before and after meridian transit time.

DATE	MERIDIAN TRANSIT TIME
12/01/23	08:15 PM
12/03/23	09:53 PM
12/06/23	07:23 PM
12/08/23	09:01 PM
12/13/23	08:09 PM
12/15/23	09:47 PM
12/18/23	07:17 PM
12/20/23	08:56 PM
12/25/23	08:04 PM
12/27/23	09:43 PM
12/30/23	07:13 PM
01/??/24	??:?? PM

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Calendar of Night Sky Events

DATE	EVENT
12/07/22	Full Moon.
12/07/22	Mars at opposition. — The best time to see our red neighbor. More info
12/14/22	Peak of Geminids meteor shower.
12/16/22	Last Quarter Moon.
12/21/22	Mercury at greatest eastern elongation. — Visible in the west after sunset.
12/21/22	Southern Solstice. — Official beginning of our winter.
12/22/22	Peak of Ursids meteor shower.
12/23/22	New Moon.
12/29/22	Appulse of Mercury and Venus. — Separated by 1.4°
12/29/22	First Quarter Moon.
01/03/23	Peak of Quadrantids meteor shower.
01/04/23	Earth at perihelion. — Our closest approach to the Sun for the year.
01/06/23	Full Moon.
01/07/23	Mercury at inferior conjunction. — Passing between us and the Sun.
01/14/23	Last Quarter Moon.
01/21/23	New Moon.
01/22/23	Appulse of Venus and Saturn. — Separated by 0.4°
01/28/23	First Quarter Moon.
01/29/23	Mercury at greatest western elongation. — Visible in the east before sunrise.

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Deep Sky

The summer Milky Way is now partially below the horizon at the beginning of the night, but the winter Milky Way is getting more and more prominent.  There are many open star clusters that can be seen with only binoculars scanning this part of the sky.  For example we have the asterism of the Coathanger between Aquila and Cygnus in the fainter constellation of Vulpecula.  The Pleiades (M45) is visible naked-eye in the east just above the face of Taurus which itself is another cluster called the Hyades.  We also have the Double Cluster in Perseus high in the north-northeast.  Finally, the constellation of Auriga in the northeast contains M36, M37, and M38 in close proximity.

There aren't as many globular clusters we can see this time of year, but there are still a few.  M15 is visible near the head of Pegasus in the west-southwest.  The next brightest one is M2 in Aquarius to the southwest.

For nebulae, we have several in the plane of the galaxy, one of which is the North America Nebula (C20) to the west-northwest in Cygnus.  The spectacular Orion Nebula (M42) is now just rising at the beginning of the night in the east. For planetary nebulae we have the Ring Nebula (M57) in Lyra, the Dumbell Nebula (M27) in Vulpecula, and the Blue Snowball (C22) in Andromeda.

And now the galaxies:  Our neighbor the Andromeda Galaxy (M31) is now very high in the middle of the sky and is visible on dark nights with the naked eye.  Also nearby is the Triangulum Galaxy (M33), visible with binoculars.

Interesting Deep Sky Objects to Observe during December and January (during observatory hours)

DESIGNATION	NAME	APPARENT MAGNITUDE	APPARENT SIZE	DISTANCE (LIGHT-YEARS)	TYPE
Messier 45	Pleiades	1.6	110'	440	open cluster
Messier 31	Andromeda Galaxy	3.4	3° x 1°	2,900,000	spiral galaxy
Messier 44	Beehive Cluster	3.7	95'	577	open cluster
Messier 42	Orion Nebula	4	85' x 60'	1400-1600	diffuse nebula
Messier 33	Triangulum Galaxy	5.7	67' x 42'	3,000,000	spiral galaxy
NGC 7293	Helix Nebula	7.3	16'	450	planetary nebula
Messier 27	Dumbbell Nebula	7.4	8' × 6'	1,250	planetary nebula
NGC 7009	Saturn Nebula	8	36"	2,400	planetary nebula
Messier 81	Bode's Galaxy	8.5	21'	1,200,000	spiral galaxy
Messier 57	Ring Nebula	8.8	1'	2,300	planetary nebula
Messier 82	Cigar Galaxy	9.5	14'	1,200,000	galaxy

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Frequently Asked Questions

What is happening in space in 2023?

There are several events coming up that we can look forward to whether you have a telescope or just like following astronomy/space news.

One of the most exciting events is an annular solar eclipse happening on Oct 14.  It is partially visible (about 78%) from Tucson, but if you want to see the "ring of fire" you only need to travel as far as the four corners region or central New Mexico.

For meteor showers, your best bets are the Lyrids (Apr 22), the Perseids (Aug 13), the Orionids (Oct 21), and the Geminids (Dec 14).

There are also several exciting space launches scheduled for 2023.  Some of these dates are tentative, but here is what we can look forward to.  A lunar lander called Peregrine is expected to launch in the first quarter of the year.  JUICE, which will explore Juipter's moon Ganymede, is scheduled to launch in April.  The Venus Life Finder is scheduled for May, which will search for biosignatures in Venus's atmosphere.  IM-1 and IM-2, lunar exploration missions with multiple components, are scheduled for March and the second quarter of the year, respectively.  Chandrayaan-3, containing another lunar rover is scheduled for June.  A private crewed flight around the Moon called DearMoon and a lunar lander called SLIM are anticipated in 2023, but dates are pending.  The lunar lander Luna 25 is scheduled for July.  The return of OSIRIS-REx's sample of asteroid Bennu will happen in September.  The asteroid mission Psyche is currently scheduled for October.  Another mission containing a lunar rover called MoonRanger is scheduled for November. There are many more scientific missions such as space telescopes and earth satellites to keep an eye out for as well.

Finally, there are a few major anniversaries to note:  April marks the 50th anniversary of the launch of Pioneer 11, the first mission to visit Saturn.  In May is the 50th anniversary of SkyLab, the first US space station.  And in November is the 50th anniversary of the launch of Mariner 10, the first spacecraft to visit Mercury.

So you see there's a lot happening in 2023.  So keep your eyes on the sky!

If you have any questions you'd like me to answer in the next issue of SWG, please let me know.  I'm also happy to take suggestions or comments, and also pictures if you'd like to send them.  Happy viewing!

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