 What
were you doing exactly 40 years ago this month?
For those of us who were around way
back in July 1969, we were anticipating the greatest technological
accomplishment of the age. We were
waiting for Apollo 11. It was a
moment frozen in time when the world's population joined hands in a collective
"can-you-believe-it" moment.
We
can recapture some of that excitement by visiting the Moon not just once, but
throughout the entire month as we mark the 40th anniversary of Apollo 11.
July
opens with a huge waxing gibbous Moon looming in the southeast after sunset.
On July 1, sunrise will have just come to the magnificent crater Copernicus, lying as an island among the flat lava plain known as Oceanus
Procellarum, the Ocean of Storms.
The
next night, sunlight awakens Sinus Iridum.
This crescent-shaped "
Bay
of
Rainbows
" is actually half of the rim of a large impact crater flooded by lava from
Mare Imbrium more than 3 billion years ago.
As
time passes toward Full Moon on July 7, watch as the brilliant rays of ejected
material surrounding Copernicus appear to almost explode like a burst of
fireworks. A smaller display
surrounds the crater Kepler, west
(left) of Copernicus, while a huge skyrocket blasts away from the crater Tycho.
The
Moon rises later after sunset on each succeeding evening as the terminator
sweeps across the disk from lunar east to west.
Tranquility Base, where Neil Armstrong and Edwin Aldrin left their
historic footprints, sees the Sun set on July 12.
By
the following night, the terminator will have swept near three prominent craters
in a north-south line. The largest,
spanning some
93 miles
in diameter, is Ptolemaeus. To its
south, we have Alphonsus, at
71 miles
across. Smallest of the three is Arzachel,
59 miles
across. A larger crater, Albategnius
(
82 miles
), lies between the three and the terminator, while Purbach
(
71 miles
) is just to their south. By the
next night, all five will lie in darkness.
The
Moon. Map based Virtual
Lunar Atlas software, available for free at http://www.ap-
i.net/avl
Image © Virtual Moon Atlas/JPL.
Used with permission. Read
more about VMA at http://www.cloudynights.com/item.php?item_id=1811
Come
the last week of the month, the Moon rejoins the evening sky.
Can you spot the thin crescent of the day-old Moon on July 22?
How about July 23? It takes a
near-perfect western horizon and haze-free skies to see such a young Moon.
There
is more to see than just the slender crescent, however.
Look carefully and you will see the entire outline of the lunar disk,
including the greater portion not yet illuminated directly by sunlight.
This effect is known as earthshine. Were we on the Moon, we would see
Earth going through phases just like the Moon, but in reverse order.
In other words, when we see a crescent Moon here on Earth, an astronaut
on the Moon would see a gibbous Earth.
By
July 23, Mare Crisium comes into
view. Two nights later, Mare
Fecunditatis has seen the Sun rise. Can
you see two craters along its eastern shore, Langrenus
and Petavius?
They span
80 miles
and
100 miles
, respectively.
Mare
Tranquilitatis and Tranquility Base see
sunrise on July 27. Sorry, you won't
see the flag, but the landing site is near the southwestern shore (lower left
edge) of the mare's dark gray outline.
First
Quarter on July 28 is wonderful through binoculars.
That night, sunlight just grazes the Caucacus
and
Apennine
Mountains
that mark the western rim of Mare
Serenitatis.
But
my favorite phase of all comes two nights later, when magnificent Clavius
sees first light. Clavius,
136 miles
in diameter, is large enough to be visible through 7x binoculars when it rides
the terminator, as it will that night. Look
for it among the rugged highlands near the Moon's southern edge, or limb.
By
month's end, the terminator is back where we began, bringing dawn to Copernicus
and the
Ocean
of
Storms
.
How
many of the surface features listed here are you able to identify through your
binoculars? Can you spot others not
mentioned? Drop me a line at phil@philharrington.net
and let me know. I'd like to include
them on our next trip to the Moon.
Till
next month, remember that two eyes are better than one.
--------------------------------------------
Phil Harrington's
Binocular Universe is copyright
2009 by Philip S. Harrington. All rights reserved.
No reproduction, in whole or in part, beyond single copies for use by an
individual, is permitted without written permission of the copyright holder.
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