The Sky This Month
Waxing and Waning
Brian Biggs
Welcome to our night-time sky. Please enjoy
this month’s tidbits of knowledge. We are
lucky to live in a dark-sky area where the
heavens can shine through. I hope you enjoy
the sky and perhaps learn a thing or two.
Happy star gazing!
Wax On, Wane Off – Ok, Mr. Miyagi is not an astronomer,
but a play on his instructions to the Karate Kid might help
you remember how the Moon gets bigger and smaller. In
May, the Full Moon occurs on the 3rd. At 9:22pm, the Moon
is opposite the Earth from the Sun, and we can see the full
reflection of the Sun’s rays. The Moon rises at sunset and
sets at Sunrise. The Moon then wanes, getting smaller and
smaller in the reverse pattern from Waning Gibbous to Last
Quarter (May 11th) to Waning Crescent to a New Moon in
a 29.5 day cycle. On May 17th at 10:13pm, the New Moon
is between the Earth and the Sun so we cannot see any light
reflecting from the Moon. The Moon rises at Sunrise and sets
at Sunset. From then on, the Moon waxes into view growing
from Waxing Crescent to First Quarter (May 25th) to Waxing
Gibbous to a Full Moon on June 2nd. You might also keep in
mind that the Moon grows from right to left, so if the light is
on the left, the Moon is waning towards a New Moon.
As Long As You’re Looking Up – You might as well take a
look at another orbiting phenomenon – the Iridium Flare.
Iridium is a constellation of 66 communication satellites (plus
spares) orbiting the Earth to provide world-wide voice and
data communication. You probably won’t have much need to
use an Iridium satellite phone unless you’re climbing Mount
Everest or sailing the open seas, but you can still enjoy their
optical magic trick. If conditions are just right as you watch
an Iridium satellite pass by, the satellite will suddenly “flare”
and get extremely bright (magnitude -8). The satellite will
remain bright for 5-20 seconds and then dim out. What’s
happening? You Boy Scouts out there know the answer if
you have ever used