THE USM SOUTHWORTH PLANETARIUM
207-780-4249     www.usm.maine.edu/planet
70 Falmouth Street     Portland, Maine  04103
43.6667° N                   70.2667° W
Altitude:   10 feet below sea level
Founded January 1970
Julian date:  2458652.5
                      "We love the Universe .  It's great!"

THE DAILY ASTRONOMER
Tuesday, June 18, 2019
More Moon Demytification

Ask most scientists and they'll tell you, either lamentably or cheerfully,
that no matter how long they labor or how ardently they strive, they'll
never solve all the mysteries.   Quite often, in fact, the answer to one
question will prompt others: like the fearsome Hydra sprouting two heads
out of each bloodied stump, just to wax poetic.      Well, yesterday's moon
demystification article has lead to other moon based questions and myths
that we want to promptly address before moving on to other topics.

*THE MOON REFLECTS MOST OF THE  SUNLIGHT IT RECEIVES?*
Status:   MYTH
The moon reflects about six percent of all incidental sunlight on average.
Astronomers measure the ratio of a body's reflected to incidental sunlight
with a value called "albedo."   A body with an albedo of 0 absorbs all
incoming light.  A body with an albedo of 1 reflects all incoming light.
 The moon's albedo is 0.07.
This number is an average as the darker parts of the moon such as the
"maria," absorb more light that surrounding regions.

*THE MOON IS THE LARGEST MOON IN THE SOLAR SYSTEM?*
Status:  MYTH...with qualifications

In absolute terms, the moon ranks fifth in size of all the moons in the
solar system.       The moon's diameter is 3,475 kilometers.     Jupiter's
largest moon, Ganymede, with a diameter of 5,262 kilometers, is the solar
system's biggest moon.     However, in terms of  size relative to orbiting
body, the moon ranks second.     Pluto's moon Charon is the largest moon in
the solar system when measured relative to its parent body. A it is about
1/9th as massive as Pluto, Charon actually doesn't revolve around Pluto.
Instead, Pluto and Charon revolve around a common barycenter.  However, if
one subscribes to the preposterous notion that Pluto isn't a planet, then,
yes, when measured in relation to its parent body, Earth's moon is the
solar system's largest.

*PIECES OF THE MOON ARE SCATTERED ON EARTH?*
Status:  FACT

Scientists know that Earth's surface contains innumerable pieces of the
moon, more formally known as "lunar meteorites."      When an asteroid
strikes the moon, fragments of the moon will be propelled about the lunar
terrain.  As the moon's gravity is about one-sixth that of Earth,  many of
these pieces achieve escape velocity and fly away from the moon.
Naturally, many of these dislodged pieces will crash onto the nearest large
body to the moon, our planet Earth.   Researchers are able to identify
lunar meteorites by chemical analysis:  they will match the composition of
moon rocks that astronauts brought back to Earth on purpose.

[image: image020.jpg]
A* lunar meteorite *found in Antarctica in January 1989.


*ALL THE MOON WALKERS HAVE DIED?*
Status:  MYTH
Twelve astronauts walked on the moon's surface.  Neil Armstrong, the first
astronaut to set foot on the moon and Eugene Cernan, the last astronaut to
walk on the moon, have both died.   However, four other moon walkers still
remain:

Buzz Aldrin (Apollo 11)
David Scott (Apollo 15)
Charlie Duke (Apollo 16)
and
Harrison Schmidt (Apollo 17)

*THE AMERICAN FLAG HAS BEEN BLEACHED WHITE?*
Status:  Almost certainly true
The American flag was vibrantly colored with the red, white and blue when
it was planted in the lunar soil.  However, after the passage of so many
years under the scorching Sun, the flag has most likely been bleached
white.     We know, ourselves, that clothes can and do fade here on Earth
if they worn outside excessively.  However, on the moon, the Sun is much
harsher owing to the  the lack of any protective atmosphere.      Colors
fade rapidly.

*THE FOOTPRINTS LEFT BY THE ASTRONAUTS ARE STILL ON THE MOON'S SURFACE?*
Status: FACT

If we teleported to the moon right now, we'd see the astronauts' footprints
pressed onto the lunar soil looking so fresh one would have thought the
astronauts had just left them.    The moon lacks Earth's erosion mechanisms
of wind and water, so craters and other imprints will remain on the moon
for quite a long time.     In fact, the astronauts' footprint will only be
wicked away by the tediously slow process of micrometeorite impacts.  We
estimate that the footprints, if left alone, will remain on the moon for at
least the next 500,000 years!