66 ASTRONOMY • OCTOBER 2019
OBSERVING BASICS
International Observe the Moon Night
(InOMN) will occur on the evening of Saturday,
October 5. Held annually since 2010 — tradi-
tionally on a Saturday in September or October during the
First Quarter Moon, when the Moon is at its best for tele-
scopic viewing — InOMN encourages people around the
world to observe and learn about the Moon. Below are
some interesting facts that you might want to
share with your guests should you take part in
a public InOMN event.- The Moon is one-quarter the diam-
eter of Earth and roughly a quarter million
miles (400,000 kilometers) away. If Earth were
shrunk to the size of a basketball, on average,
the Moon would be the size of a tennis ball
about 25 feet (7.5 meters) away. - Lunar daytime (sunrise to sunset) lasts
about 14¾ days. Same with a lunar night. For
this reason, and because the Moon has no atmosphere, the
sunlit half of the Moon reaches a temperature of around
250 degrees Fahrenheit (120 degrees Celsius), while the
night side is a chilly minus 290 F (minus 180 C). That’s a
day-night difference of 540 F (300 C). - The Moon’s gravity is about one-sixth that of
Earth’s. A world-class weightlifter capable of lifting
450 pounds (200 kilograms) on Earth could hoist
2,700 pounds (1,225 kg) on the Moon. A golfer who can
smack a 350-yard drive would launch a golf ball more than
1.2 miles (1.9 km) at the Sea of Tranquility Country Club. - The lunar maria really are seas — seas of lava.
Billions of years ago, volcanic activity allowed molten
material from the Moon’s interior to f low to the surface
and fill in lowland regions. These lava oceans eventually
cooled to form dark basaltic plains. Little of the Moon’s
surface has changed since. For that reason, the naked-eye
Moon looks essentially the same to us as it did to the dino-
saurs — albeit a little smaller. - That’s because the Moon is slowly ditching
Earth. Each year, the Moon drifts about 1.5 inches
(3.8 centimeters) away from us. About 170 million years
ago, during the middle of the Jurassic Period, the Moon
was some 4,000 miles (6,400 km) closer to Earth. But you
wouldn’t notice the difference. - From Apollo landers to Moon buggies to
unmanned lunar probes, humans have left about 200 tons
of material on the Moon. But they’ve also brought pieces
of the Moon back to Earth. From 1969 to 1972, Apollo
astronauts collected 842 pounds (382 kg) of Moon rocks
and soil for return to Earth. - The footprints left behind by the Apollo 11
astronauts are still there after a half century. Because the
Moon lacks an atmosphere, there is no wind or rain to
erase them. Micrometeorites do slowly erode the surface;
however, unless a significant meteorite obliterates the
landing site with a direct hit, the footprints will remain for
millennia to come. - The Moon smells! But it doesn’t smell like the
fabled green cheese. Apollo 11 astronaut Buzz Aldrin
noted that fresh regolith (Moon dust and dirt) smelled
“like burnt charcoal or similar to the ashes that are in a
fireplace, especially if you sprinkle a little water on them.”
Astronaut and geologist Harrison Schmitt of Apollo 17
concurred, noting that the lunar soil left the
cabin air smelling like spent gunpowder. - A telescopic view of the Moon can be
an life-altering sight to young eyes. So here’s a
motivational fact to share with any school-
a ged ch i ld ren: T hei r nex t close-up v iew of t he
Moon could be from its surface. By studying
hard, they might be able to join a scientific
team stationed at a future Moon base!
The bad news: Manned exploration of
the Moon has been dead for decades. The
Apollo era ended with the Apollo 17 lunar lift-off on
December 14, 1972. The good news: We’re going back
soon. This March, Vice President Mike Pence announced
Americans will aim to return to the lunar surface by 2024.
Stay tuned.
Questions, comments, or suggestions? Email me
[email protected]. Next month: Watch Mercury cross
the Sun! Clear Skies!
Prepare yourself by brushing up on your lunar trivia.
A night dedicated
to the Moon
Children look up in
wonderment at a
display of the Moon
during a public event
hosted by NASA’s
Goddard Space Flight
Center. This event took
place during the fifth
anniversary of
International Observe
the Moon Night, which
encourages everyone
across the world to
gaze upward and
appreciate our nearest
celestial neighbor.
NASA/GSFC/BILL HRYBYK/FLICKRThe Moon
smells! But
it doesn’t
smell like the
fabled green
cheese.
BY GLENN CHAPLE
Glenn has been an
avid observer since
a friend showed
him Saturn through
a small backyard
scope in 1963.BROWSE THE “OBSERVING BASICS” ARCHIVE
AT http://www.Astronomy.com/Chaple