Astronomy

64 ASTRONOMY • DECEMBER 2015

I

n response to my August

2013 column, “Elvis and

the alphabet,” in which I

made reference to the Lunar

X, Richard Edmonds of

Flagstaff, Arizona, emailed: “You

didn’t include an image of the

X and I didn’t retain my copy of

the September 2012 issue where

you featured it and may have

included an image. I searched

my recent lunar photographs

and found this image. Is this the

Lunar X to which you refer?”

I looked at the image. It

wasn’t. The X that I described

is the one associated with the

crater Werner, located near the

lunar meridian about a third

of the way up from the lunar

south pole and visible for only a

few hours around First Quarter

Moon. The X that Edmonds

found is close to the crater

Mutus near the lunar south pole

and is observable for several

consecutive evenings after Full

Moon. He had stumbled upon

it while “strolling” around a

19-day-old Moon with a 10-inch

OBSERVINGBASICS

BY GLENN CHAPLE

The Mutus X

Seek out this interesting feature of light and shadow

a few days after Full Moon.

month but that lunar libration

[the Moon’s side-to-side and

up-and-down wobble] has a

significant effect on the shad-

owing that can bring out the X

in sharp contrast. Several times,

even with an active imagina-

tion, the X was not recognizable

due to libration.”

Now it’s your turn to dis-

cover the Mutus X. The labeled

guide on this page, taken from

Edmond’s all-Moon photo,

retraces the path I took from

Theophilus to the X. Conduct

your search a few days after

Full Moon when the terminator

(the dividing line between night

and day on the lunar surface)

reaches the eastern edges of

the Sea of Tranquillity and the

Sea of Nectar. Make the crater-

hop with low power, and then

switch to high magnification

(10 0 x or more).

Once you’ve spotted the

Mutus X, be sure to look a

little farther south to another

interesting feature Edmonds

encountered. “By the same

strolling method that netted the

X,” Edmonds relates, “this guy’s

face popped out at me. This one

was quite startling considering I

was not expecting it. A bit com-

ical when you get used to it.”

This miniature “Man in the

Moon” is formed by the craters

Schmidt-Cassegrain telescope

and imaging equipment.

Mutus is in an area littered

by craters like dimples on a golf

ball. To find the Mutus X, I’d

need to crater-hop much the way

I star-hop when seeking a deep-

sky object in a star-rich region.

Fortunately, Edmonds had

included a whole Moon image

that pinpointed its position.

On the evening of Sept-

ember 22, 2013, 4½ days after

Full Moon, I tried my luck.

Starting with the prominent

three-crater chain formed

by Theophilus, Cyrillus, and

Catharina, I jumped to the cra-

ter Fracastorius on the southern

shore of the Sea of Nectar and

then to Piccolomini farther

south. A southeastward jaunt

from Piccolomini brought me

to the huge crater Janssen and

then, with a southward turn,

to a crater group surround-

ing Hommel. Continuing the

southerly drift finally brought

me to the crater Mutus and, just

below it, the X.

Without the chart, I doubt I

would have found the Mutus X.

Barely half the size of Jupiter’s

disk, it was just visible through

my 4.5-inch ref lector at 150x

and still appeared small in a

10-inch ref lector at 208x. Its

image contorted by atmospheric

turbulence, it was indeed a

challenge to capture!

After spending a year study-

ing the Mutus X, Edmonds

concludes: “It takes an 18- to

19-day-old Moon to really see

it. ... It seems to result in part

from a shadow on the western

side of Mutus F [a companion

crater to Mutus] and a smaller

crater immediately to the north.

I would say the X is visible every

Simpelius and Simpelius A (the

eyes) and Schomberger (the

mouth). Between the eyes and

mouth, shadows in a small cra-

ter create nostrils.

Last July, three days after

Full Moon, I checked out the

Mutus X and then looked for

the face. Even with low mag-

nification, it was easily visible.

The smile was wider than

that in the image Edmonds

sent (shown above), stretching

into adjacent Schomberger C

and creating a wide troll-like

grin. The following night,

the mouth was limited to just

Schomberger Crater, becom-

ing the silly grin Edmonds had

imaged — from troll to droll in

a single evening!

His experience leads

Edmonds to surmise, “I’m sure

there are other real and imagi-

nary objects to be found on

the Moon.” There are! As the

terminator drifts east to west

across our satellite’s surface,

dozens of clair-obscur (liter-

ally, light and shadow) features

come and go. For an extensive

list, log on to http://www.the-moon.

wikispaces.com/clair-obscur.

Questions, comments,

or suggestions? Email me at

[email protected]. Next

month: The LVAS Observer’s

Challenge! Clear skies!

BROWSE THE “OBSERVING BASICS” ARCHIVE AT http://www.Astronomy.com/Chaple.

While searching his images of the Moon for the Lunar X, the photographer came across

two interesting features near the crater Mutus. RICHARD EDMONDS

Corrections

On p. 47 in the August

issue, the Big Bear Solar

Observatory was incor-

rectly cited as closing in

2017. Officials say they
      expect funding to continue
      for the foreseeable future.
      — Astronomy Editors

On p. 58 in the August

issue, “8 Metis” should be

“9 Metis” under the illus-

tration. — Astronomy Editors

FROM OUR

INBOX

Theophilus

Cyrillus

Catharina

Fracastorius

Piccolomini

Janssen

Hommel

Mutus

“The Face” Mutus X