Dr. Robert Agnew (shown above sitting atop an ancient Mayan observatory
in Mexico) is a Professor of Music and
Humanities at Edison State College in Piqua, Ohio. Born in Youngstown, Ohio, Robert has a Masters Degree
from Bowling Green State University and a Ph.D. from Michigan State University
Hidden
Mysteries of the Moon
For many amateur
astronomers, the Moon is an object to avoid. Indeed, its light makes
seeing dim objects, like galaxies, nebulae, and globular clusters, very
difficult - if not impossible.
But
the Moon truly is an amazing satellite, and is well worth frequent
observation. Not only are we fortunate enough to have such a large,
airless, and waterless world near us (the fact that the moon is airless
and waterless means that erosion will not constantly change the surface
- and we can see the actual result of asteroid and meteorite
bombardment, early volcanic activity, and crustal movement spanning
billions of years), but it also provides a seemingly endless variety of
shapes and structures through the telescope.
Since
the observation is best near the terminator (the line between the light
and dark sides of the Moon), and the terminator moves from night to
night, the view is constantly changing.
Among
my favorite objects on the Moon are Domes and Rilles, primarily because
they are fairly difficult to view and are amazingly subtle. Domes are
certainly a result of ancient volcanic activity, but their origins are
not entirely understood. They are low, rounded elevations and are a
great test of an observer’s patience and fortitude. Rilles
are narrow valleys caused by lava flows on the ancient Lunar surface,
and are equally difficult to observe.
Probably
the best way to get a feel for my fascination with these objects is to
quote from my Night-Sky Journal.
December
10, 2005:
“To the southwest of Copernicus is a small crater,
Hortensius, with a series of small domes to its north. The terminator
was just at that point, and I could see the sun outlining the top of
the largest dome just north of Hortensius, and some of the other domes,
though the play of light at the terminator made for a difficult
determination of true shapes. The effect was magical!”
December
12, 2005:
“North
of Herodotus and west of Aristarchus is a volcanic dome, known as Cobra
Head, that appeared quite mountainous. Moving northwest from Cobra Head
is a long, magnificent rille known as Schröter’s
Valley. It forms an irregular half-circle, extending 160 kilometers and
measuring about 10 kilometers wide near the Cobra Head. To observe this
was like traveling to a fascinating and exotic land in a sci-fi
novel.”
December
13, 2005:
“Visible
tonight were the Rümker Hills, a volcanic dome measuring about
65 kilometers across. They appeared as a dark uplift, resembling a
short mountain chain in an otherwise featureless part of the moon. The
Rümker Hills are the smallest and northernmost of three
volcanic complexes. They are truly striking!”
December
19, 2005: On the eastern
side of crater Janssen, a series of small craters looked like the last
part of a flat stone skipping on water (they appeared to get closer and
closer as they entered Janssen). There is an arcuate rille in the west,
interior that is absolutely fabulous through the eyepiece (its origin
is still a mystery - and it is the only major rille in the highlands).
January
20, 2006:
“I’ve
searched for the Valentine Dome several times before, but did not
manage to observe it until this morning. The Valentine Dome lies just
southeast of the Caucasus Mountains, with a stranded mountain helping
to point to the Dome as one moves from the southern tip of Montes
Caucasus east to the Valentine Dome.
It
was not on the terminator, but was obviously close enough to
distinguish readily (the light must be right or there is no chance of
seeing this subtle feature). I got a splendid look at this broad (30
kilometers wide), low (100 meters high) volcanic dome. To me, it looked
much more like a beetle or a scarab than a valentine (so called because
of its heart shape), but it was certainly an interesting formation.
The
Valentine Dome is noticeably bright on its southern end, actually a
triplet of small hills protruding from it.”
It
is quite understandable why some amateur astronomers, instead of
cursing the Moon, devote most of their attention to observing our
beautiful celestial companion.
Making
a “small step” of introducing yourself to Lunar
observation can, indeed, give you a “giant leap” of
breathtaking objects, as foreign and as strange as any that can be seen
through a backyard telescope, with enough variety to last a lifetime!
©
Article & image Dr. Robert Agnew 2008/2009
