2022, December 11: Andromeda Galaxy, Star Cluster, Nightly Planet Display


December 11, 2022: The Andromeda galaxy and a globular star cluster are visible above Jupiter and Saturn during the evening.  Mars joins the other two planets for a nightly display.

Photo Caption – (11 Dec. 1972) — The Lunar Module (LM) is in the background of this view of the Taurus-Littrow landing site. (NASA Photo)


by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:08 a.m. CST; Sunset, 4:20 p.m. CST.  Check local sources for sunrise and sunset times for your location.

Today’s sunset time is the earliest of the year.  This continues through the 14th.

Jupiter’s Great Red Spot’s transit times, when it is in the center of the planet in the southern hemisphere: 7:49 UT, 17:44 UT; Dec. 12, 3:40 UT.  Convert the time to your time zone. In the US, subtract five hours for EST, six hours for CST, and so on.  Use a telescope to see the spot.  Times are from Sky & Telescope magazine

This is the 50th anniversary of the last Apollo lunar mission – Apollo 17.  December 11, 1972, was the mission’s fifth calendar day. On this day, Eugene Cernan and Harrison Schmitt landed on the moon.  Ronald Evans remained in the command module.

From NASA’s summary of the event: “Landing occurred at 19:54:58 GMT (02:54:58 p.m. EST) on 11 December at 110:21:58, mission elapsed time. The spacecraft landed in the Taurus-Littrow region at latitude 20.19080° north and longitude 30.77168° east, within 656 feet of the planned landing point. Approximately 117 seconds of engine firing time remained at landing.”

Four hours later, the moon walkers emerged from the lunar lander for their first exploration of the surface that lasted over seven hours.  They used the third lunar rover to roll on the to set up experiments, take photographs and collect rocks.

Summaries of Current Sky Events

Here is today’s planet forecast:

Morning Sky

Chart Caption – 2022, December 11: The moon is lined up with Pollux and Castor before daybreak.

An hour before sunrise, the bright gibbous moon, 90% illuminated, is less than halfway up in the west.  The lunar orb, Pollux, and Castor – the Gemini Twins – seem to be in a line.

The moon is 3.0° to the left of Pollux and Castor is 4.5° farther to the right of its twin.  With the moon’s brightness, it may be necessary to block the moon’s glare with your hand as you would to shield your vision from the sun.

Chart Caption – 2022, December 11: Before sunrise, Mars is low in the west-northwest.

Mars is lower in the sky, less than 10° up in the west-northwest.  Past opposition, the planet is setting earlier each morning.

Evening Sky

Chart Caption – 2022, December 11: Jupiter and Saturn are in the southern sky after sundown.

Venus and Mercury are still hiding in bright twilight.  For sky watchers wanting a challenge, they can be found in the southwest twenty minutes after sundown. An unobstructed, cloudless horizon is needed to find them.  A binocular is needed to see them in the bright twilight.

First locate Venus with a binocular.  It is less then 5° up and less than 10° to the right of the southwest point.  Once it’s located, move it toward the lower right portion of the field of view.  Then in the upper left part of the field, Mercury is 5.4° to the upper left of Venus.

The five bright planets are in the sky now.  Perhaps Jupiter is visible without optical aid in the southeastern sky.  Saturn is very difficult to find at this time because it is dim. In about two weeks the five bright planets are visible simultaneously after sunset in a darker sky

Chart Caption – 2022, December 11: Jupiter and Saturn are in the southern sky after sundown.

By an hour after sunset, Venus and Mercury are below the southwest horizon.  Bright Jupiter stands out about halfway up in the south-southeast.   The Jovian Giant is slowly moving eastward against the stars of Pisces.

Saturn, also moving eastward, is with the stars of eastern Capricornus, less than 40° to the lower right of Jupiter and about one-third of the way up in the south-southwest.

Chart Caption – 2022, December 11: Pegasus and Andromeda are high in the southern sky. Look for a globular star cluster (M 15) and a galaxy (M 31) with a binocular.

Without the moon during the early evening, dimmer stars are visible, especially away from the permanent glow of outdoor lights.  Pegasus and Andromeda are higher in the southern sky than Jupiter and Saturn.

The two constellations seem to be connected and are part of the Perseus legend.  Pegasus, the Great Winged Horse, is upside down for northern hemisphere sky watchers.  The Great Square is reasonably easy to locate.  In celestial artwork, the figure is emerging from clouds. Its neck and nose, Enif, extend westward.  Pegasus’ stars are about the brightness of those in the Big Dipper.

Photo Caption – The dazzling stars in Messier 15 look fresh and new in this image from the NASA/Hubble Space Telescope, but they are actually all roughly 13 billion years old, making them some of the most ancient objects in the Universe. (NASA Photo)

The globular cluster, Messier 15 (M 15 on the chart) is easy to locate.  From the countryside, it is visible to the unaided eye and easily through a binocular.  It appears in the same binocular field with Enif, making its location easy to find.

M 15 is about 40,000 light years away, outside the plane of the galaxy and contains hundreds of thousands of stars.

Globular star clusters, like M15, are different from galactic clusters, like the Pleiades star also known as the Seven Sisters.  Globulars revolve around the galactic center outside the plane of the galaxy, have more stars to make the globular appearance, have a distinguishable composition, and are older than stars inside the galactic plane.

About a century ago, the globulars’ locations were mapped.  This indicated the location of the Milky Way’s center, now thought to have a giant black hole, and the sun’s location away in the galactic suburbs.

Image Caption – The Andromeda Galaxy, also known as M31 since it is the 31st object on Messier’s list of diffuse sky objects, is the nearest large galaxy to our own Milky Way galaxy. Our galaxy is thought to look much like Andromeda. (NASA photo)

In addition to knowing the basic structure of the galaxy, another more famous feature, the Andromeda Galaxy, cataloged as Messier 31 (M 31 on the chart), is far beyond the constellation’s stars.  Its initial distance was first measured about the time the galaxy’s shape and structure were observed. Today, the galaxy’s distance is measured to be over 2 million light years.

The constellation Andromeda begins at Alpheratz – meaning “the horse’s navel.”  It is included in with the Great Square and could make Pegasus’ back legs. The galaxy is over two-thirds of the way up in the sky in the east.

M 31 is over 4° across, meaning that it is about eight times the apparent size of the moon.  It is best viewed with a binocular as it easily spills outside a telescopic eyepiece.

The Milky Way and the Andromeda Galaxy, along with over 20 other galaxies, anchor the Local group.  Southern hemisphere sky watchers are well-aware of the Magellanic Clouds, two satellite galaxies of the Milky Way, that are part of this clump of local galactic space.

With the moon out of the sky, attempt to find the globular and the galaxy during the early evening.

Chart Caption – 2022, December 11: Mars is in the east-northeast in front of Taurus.

At an hour after sundown, Mars is about 15° up in the east-northeast, retrograding in front of Taurus.  This illusion of westward motion continues for another month.  This evening it is 8.7° to the upper right of Elnath, the Bull’s northern horn, and 9.1° to the upper left of Aldebaran.

Photo Caption – The Pleiades star cluster. (U.S. Naval Observatory)

The Pleiades are above the Bull’s main features.  As a galactic star cluster, it has fewer stars and seemingly more space between them than a globular cluster.

By two hours after sundown, the three outer planets are making their best display.  Jupiter is halfway up in the south.  Mars is in the eastern sky, while Saturn is southwest.  Both are about 20° above their respective horizons.

Chart Caption – 2022, December 11: The moon is low in the east-northeast, four hours after sundown.

At four hours after sundown – seems late, but that’s about 8:30 p.m. CST in Chicago – the gibbous moon, 86% illuminated, is about 10° above the east-northeast horizon and 10.5° to the lower left of Pollux.

Jupiter (NASA Photo)

At 9:40 p.m., Jupiter’ Great Red Spot is in the middle of the planet in the southern hemisphere and visible through telescopes.  The planet is about one-third of the way up in the west-southwest, from Chicago.  Sky watchers farther westward see the planet high in the southern sky and in clearer air.

By tomorrow morning, Mars is low in the west-northwest.  The gibbous moon is in front of Cancer, less than halfway from Pollux to Regulus.



Leave a ReplyCancel reply