Applegater Spring 2012 7
THE STARRY SIDE
Wandering stars
BY GrEELEY wELLS
Well, ah…where are we? Has this
been winter? Did it start? Is it over? Then
maybe this is spring coming up. I guess
even if the weather is funny, the stars still
do their thing—and for them it’s definitely
spring.
So what’s up there, overhead? The
summer triangle is seen as I write this only
around dawn, but when you read this it’s
beginning to rise late in the evening. The
Summer Triangle is formed from three
bright stars: Vega, Deneb and Altar. Here’s
how to find them. By May, Vega is pretty
far up the northeastern horizon. Vega is a
bright star in Lyra, those odd sets of two-
by-two stars about equal distance to each
other. (By the way, does anyone see a lyre,
an ancient stringed instrument, in Lyra? I
sure don’t.) Below Lyra is Deneb, the top
of the Northern Cross. (The Northern
Cross is officially Cygnus the swan; in
May the swan is flying flat on the eastern
horizon, with Deneb as its tail.) By June
we should also be seeing Altar in Aguila the
eagle. Aguila is a three-in-a-row set similar
to Orion’s belt but the middle star, Altar, is
brightest. That’s the full summer triangle.
But look—there’s more! Parallel with
the big dipper high over our heads and
heading west is the big lion, Leo, with
the planet Mars still below it continuing
its dance back and forth. Mars has gone
toward Regulus, then paused, moved
away, and now is coming back. What’s
with all this weird movement? Can you
visualize what it might look like to follow
a particular planet from our viewpoint
going around the sun? It’s really hard to
visualize, so here’s a way to think about it.
If you were to watch from the side a horse
on a rope being walked around a center
post (the sun) it would go left for a while,
seem to slow down and then go right, only
to do the reverse on the other side of the
circle. Of course, there are many horses
(planets) all on various lengths of rope
from the pole. Now imagine you, yourself
have a rope attached to the same pole, and
you’re also going around the pole. Your
rope is shorter than some and longer than
others, but you’re going around the same
post. See how complicated that would be?
Now imagine it’s night and each of you
carries a differently powered and slightly
differently colored lamp: now all you see
are the lamps. Sometimes the lights are
close to you, sometimes far; some are fast,
some are slow; and some are really, really
far away. It’s totally confusing. This is the
kind of thing scientists and great thinkers
work on for years and build complicated
charts, models and theories for. So it’s
no wonder the Greeks just called these
wandering stars, and today we call them
planets.
Leo is not the only constellation
harboring a planet. Virgo has Saturn
playing with her brightest star, Spica, in
the same confusing way. Follow the arch
of the big dipper handle to Arcturus [the
bright one] and the same arch further on
to Spica [pretty bright] and the similarly
bright but not blinking “star “ nearby is
the planet Saturn. It was going away from
Spica last year and is still playing around
it because it slowed, stopped, and came
back—and is about to do it again.
In the south, close to the horizon,
is Scorpio up in the southeast in June.
Scorpio is characterized by another set of
three stars twice! The “shoulders “ of the
scorpion are a vertical three in a row. The
other three-in-a-row set is to the left and is
curved slightly downward to form the back
of the scorpion. In this row of three is the
famous red rival of Mars: Antares. The rest
of the constellation sweeps left and down
to the horizon and comes up farther left
with the stinger: two stars tightly together
in just the right spot and with the right
look for an end-of-tail stinger. Scorpio is
followed closely on the left by the teapot, or
Sagittarius the archer, which marks almost
a camera with the pinhole as the lens, and
it will give you an upside-down image of
what’s happening, completely and safely, as
you look only at the board below it. Never
look at the sun. Only a few very expensive,
specific and hard-to-find filters can be used
safely. Here are the details: the event starts
with Venus touching the sun at 2 pm on
the June 5. The midpoint is 7:30 pm, and
then the sun sets for us before the end
point. If you do this, please be careful and
have fun. On one level there’s not much
exactly the center of our Milky Way galaxy.
Scorpio and Sagittarius bracket the Milky
Way in the south as it curves gently all the
way across the sky through the summer
triangle overhead and north to Cassiopeia.
THE PLANETS
VENUS starts May as the ornament
of the sunset, bright and alone. Caster and
Pollux are above it as it slowly sinks into
the sunset. That’s bright Capella to the
upper right. Watch for a tiny and growing
crescent moon May 22 - 25, passing Venus.
Venus begins strong in May but is falling
to the horizon and fading in intensity all
month.
On the first of June, both Venus and
Mercury slip into the sun and disappear for
a while. This is the setup for the transit of
Venus across the sun; you can’t see Venus
in our sky when it’s “in” the sun.
The big deal is the transit of Venus
across the Sun on June 5. It’s the second
and last such transit of the 21st century.
A transit occurs when a planet comes
between us and the sun, making a circular
black shadow across the sun’s surface. It’s
very hard to see and dangerous to look
at directly. The best way is this: get a
white board or thick card material, make
a pinhole in another card for sunlight to
come through, hold it over the board, and
then adjust distance to focus. It will act like
to see: a black spot on the face of the sun
very slowly moving across it. However,
this very rare event is pretty amazing when
you imagine just what’s happening and
you are the witness. I plan to give it a go
somewhere near the middle of the event,
and watch for a while.
By mid-June, Venus has risen in the
morning below Jupiter and they join the
crescent moon on the morning of the June
16 for a nice show. By June 30, Venus is
catching up with Jupiter. Aldebaran is
bright nearby, too, just below Venus.
JUPITER is out of sight behind
the sun in May. Jupiter is first into the
morning sky as June begins, however. On
June 17, the crescent moon is very close to
Jupiter at dawn, with Venus below and the
Pleiades above.
SATURN is high in the south well
after sunset at
the beginning
of May. On
May 20,
Saturn has
Greeley Wells
dimmed and
passes above about five degrees above
Spica. She’ll swing by again a little closer
in August. On May 31, see the moon
join them for a threesome lineup. Saturn
comes to a halt only five degrees from
Spica on June 26, and then begins another
easterly movement. Go figure. Remember
those horses?
MARS is high in the May sky as the
month starts, but by the time it ends, Mars
is way lower in the west. It’s also getting
dimmer and moving away from Regulus.
In June, Mars is moving east against the
background stars. So this is the third
planet/star dance going on these days!
MERCURY reappears in the evening
sky the second week of June, very low, of
course.
OF SPECIAL NOTE
In May, the full moon appears on
the 6th and is called the Milk Moon or
Planting Moon. On May 26, the moon is
close to the beehive cluster in the evening
sky and worth a gander.
June’s full moon comes on the
4th and is called the Flower, Rose or
Strawberry Moon, and will have a partial
eclipse. It’s a predawn event during which
about two-fifths of the moon will enter the
earth’s dark central umbra shadow. It will
start about 2 am; the middle of the eclipse
will occur at 3 am; and it ends about 4
am. So if you manage any of those times,
especially the middle, you’ll have a good
show. Ever seen an eclipse of the moon?
I saw the last one a few months ago and
got some film of it, too.
Also on June 28, the moon’s right
next to Spica in the evening sky, and
Saturn will be around, too.
Go to www.shadowandsubstance.
com for a nice daily show of the night sky
events; the eclipse is illustrated beautifully
here as well as the Venus transit —maybe
better than the real thing.
In spring, the Milky Way is under—
or rather all around below us—but not
yet up in our sky. It’s beginning to show
on the eastern horizon, and as Cygnus the
swan rises, she brings the Milky Way with
her up into our sky. By summer, the Milky
Way will be overhead.
June 20 is the summer solstice: the
longest day with the earliest sunrise.
(Because the latest sunset falls on June 27,
it seems like this is the longest day; this is
because we tend to pay more attention to
evening time than to dawn.) This is also
the first of many June 20 solstices to come
in the years ahead.
Greeley Wells
541-840-5700
greeley@greeley.me
