Applegater Summer 2015
7
THE STARRY SIDE
Once in a blue moon
by gREELEy WELLS
Anyone eager for summer? Well…
at least a summer with no fires and
some water? Anyone confused about the
weather? I sure am.
Whether you’re eager for
summer or confused about the
weather (or both), summer is upon us. In
the summer sky, the planets’ different sizes,
speeds, and especially distances from the
sun really affect what we see. Think about
it: the earth goes around the sun in 365
days. But Mercury is the speed demon
going around the sun—and very close to
it—4.15 times in one of our earth years!
That’s why, in our sunrises and sunsets,
Mercury is seen low and moving fast.
Venus is the second speediest, taking
about 224 of earth’s days to get around
the sun. Venus also appears in our sunrises
and sunsets and is by far the brightest
planet. Venus is closely followed by Jupiter
in brightness, but Jupiter goes just once
around the sun in 12 years. That puts him
in each constellation of the zodiac for a
whole year! Right now he is moving toward
Cancer from Leo the Lion. As a point of
comparison, Mars goes around the sun in
1.88 earth years. (Mars is presently behind
the sun and invisible.) Way out there past
Jupiter is Saturn with its beautiful rings,
at 30 earth years per solar year! Saturn is
currently in Scorpio for about two and
a half years. To view each planet easily,
remember where it is hanging.
The Summer Triangle has been
in our predawn mornings for a while now,
getting higher and higher. Each morning’s
sky reveals the next season’s evening sky.
The Summer Triangle is prepared to grace
our summer, as it always does. Its bright
star Vega in the constellation Lyra comes
first, toward the northeast. Up next in
the east is the star Deneb in the Northern
Cross—technically known as Cygnus the
Swan. And finally, a little farther south, we
see Altar in the constellation Aguila: the
eagle, the three stars in a row. These are
some of the first stars out each night in the
eastern sky. As they move together across
the sky toward the west, they carry half the
Milky Way—all the way from Cassiopeia
in the north through the Triangle to
Sagittarius in the south, where the center
of our galaxy is.
This leads us to the south, which
I don’t often talk about. The stars and
Illustration: Guy Ottewell’s Astronomical Calendar 2014.
constellations
t o t h e s o ut h
tend to be dim.
Greeley Wells
I frankly don’t
know many of them, and I tend to be
seduced by the stronger, easier mid and
northern skies. Sagittarius is one of the few
southern constellations I know well. The
English call it the Teapot, and it really is.
There’s a handle on the left, a triangular
spout on the right, and a triangular top.
There’s even a spoon above. It’s really
a centaur with a bow and arrow. The
center of our galaxy is just upper right of
Sagittarius.
Other events of note
At the top of my list is the famously
regular and spectacular Perseid meteor
shower on the morning of August 13 (and
each day on either side of that). There
could be 50 to 100 meteors per hour in
clear northern dark skies near Perseus,
Capella, and Cassiopeia. The lesser Delta
Aquarids, radiating from Aquarius, overlap
and may increase the numbers.
Summer solstice is June 21, with the
longest days and shortest nights.
July has a blue moon. Two full
moons appear, on July 2 and July 31, the
latter being the blue one. It’s rare, which
is why we sometimes say “once in a blue
moon.”
A fabulous close conjunction of
Venus and Jupiter, late June-early July,
shines above the sunset and evening—oh
boy! There will be a swell scene on the
evening of July 16: close and bright Venus,
Jupiter, and Regulus. These three will be
joined by the moon on July 18, making a
small circle of bright bodies. On July 19,
an even smaller circle of the moon, Venus,
and Regulus will appear around dusk.
Greeley Wells
greeley@greeley.me
