Astronomy

50 ASTRONOMY • DECEMBER 2018

photo purporting to show the creature’s
silhouetted head and neck rising out of
the loch’s waters, right? While that photo
has been discredited, we can find Nessie’s
shadow extending onto the northeastern
side of the crater Ptolemaeus’ f loor as
the Sun rises higher in its sky. Named
by Colorado amateur Joe Adlhoch, the
effect is due to the combined shadow
of the crater’s jumbled rim and the
small interior crater Ammonius. Try

a magnification of 150x or higher for the

best views.

LUNAR CITY

(Lunar Day 8) On July 12, 1822, German

physician and astronomer Baron Franz von

Gruithuisen was observing through his

2.4-inch refractor when he thought he saw

something unusual north of the partially

f looded crater Schröter. The area is com-

posed of a series of ridges emerging from

the surrounding Mare Insularum. A cen-

tral ridge combines several parallel ridges

spread diagonally to either side to create

a unique herringbone pattern. As the low

angle of the Sun lit the region, Gruithuisen

interpreted what he saw as a city, complete

with buildings, streets, walls, and a temple.

He christened his discovery Wallwerk.

Take a look the next time the Sun is rising

over this area and see if you can imagine

Gruithuisen’s “city.”

HESIODUS SUNRISE RAY

(Lunar Day 8.3) Look along the terminator

the night after First Quarter for the craters

Pitatus and Hesiodus, which touch one

another. As the Sun just rises in their sky, a

gap in the adjoining walls casts a long sun-

rise ray that looks like a searchlight beam

across the otherwise shadowed crater f loor.

Crank up the magnification past 100x to

examine the ray’s appearance.

EYES OF CLAVIUS

(Lunar Day 8.5) Clavius is the third-largest

lunar crater visible from Earth. You’ll also

find several craters on its f loor, which

spans 136 miles (225 km). When light from

the rising Sun first strikes the rims of two

of these, known as Clavius C and Clavius

D, it looks as though there are two hollow

eyes staring up from Clavius’ shadowed

f loor. Binoculars are enough to see Clavius

looking intently back at you.

QUINCUNX

(Lunar Day 8.7) If you’re familiar with

dice, then you’ve seen a quincunx even if

you didn’t know it by name. A quincunx is

an arrangement of five objects, with four

at the corners of a square or rectangle and

the fifth at its center. The best example of a

quincunx is the five on a die. For the pur-

poses of this story, the Moon rolls the dice

every time the Sun rises over the mighty

crater Copernicus. Just to its north, several

peaks in Montes Carpatus poke up from

the surrounding plain. As sunlight begins

to slip down the wall of Copernicus, it

also just strikes the five highest mountain

peaks, lighting them up in an almost per-

fect quincunx pattern. The Quincunx was

first spotted, and subsequently christened,

by Michael Rowles of Crofton, Maryland,

on the evening of May 11, 2011.

EIN MOUNTAINS

(Lunar Day 9) In case you missed the

Quincunx, those same Montes Carpatus

morph into a pattern resembling the let-

ters E-i-N as the Sun continues to rise in

When the Moon is 8½ days past New,

sunrise above Clavius Crater causes its

two largest craterlets, Clavius D (the

larger one) and Clavius C, to form the

Eyes of Clavius. This image was taken

March 13, 2011, at 19h44m UT. DAMIAN PEACH

The larger Moon image

locates Hesiodus

Crater, and the smaller

image zooms in to

reveal the well-defined

Hesiodus Sunrise Ray

(in the smaller crater

to the left of Pitatus

Crater at center).

STEFAN SEIP/A S TROMEETING.DE