Like most people, I have always been fascinated by the night sky, the
moon, the stars and planets. Here in Oaxaca, in the high clear
atmosphere, the dark city, the sky seems very close and I sometimes like
to draw the
night skies. My friend Ayax Cruz took this nice picture of the
Moon over Soledad.
Further, Oaxaca is very far south, below the Tropic of Cancer (look at a
map), and close to the Equator. Because of this, during the winter, the
Sun passes just a little south of due overhead and in the summer
actually just a little bit north of due overhead. This means the winters
are quite mild and the hottest seasons are spring and fall. Lot of
people say May is the time to be out of Oaxaca.
It also means there is little change in the length of day or times of
morning and night and certainly no need for “daylight savings” time,
recently “mandated” in Mexico by the so-called NAFTA “trade” agreement.
Sitting here, looking up at the night sky, it also means that the plane
of the planets’ orbits is quite overhead and easy to see all year long;
it does not tip to the far south during the winter like the view from
the United States.
While the stars, way out there, are indeed beautiful and the
constellations interesting, I suppose, in a Greekly mythological way, I
have always found them static, they have never moved and they never will.
Got it? The planets, on the other hand, are alive. They are dancing across the
sky, they swoop in and out of our view, they come swinging by the earth
and way out into the farthest reaches of the solar system!
I remember I always liked to study the simple diagram of the planets’ orbits around
the Sun. It’s always drawn from above, that is, above the North Pole (northern
hemisphere elitists that we are) and the direction of the planets is
always “counter-clockwise” (this is the result of our “thinking” that
the Sun moves from left to right through the day; it doesn’t, of course,
the Earth “rotates” from right to left, but we didn’t know that when we
invented clocks). And it’s easy to note that there are two planets
closer to the Sun than Earth, little Mercury (we hardly ever see Mercury,
by the way, its orbit is so close to the Sun) and Venus (beautiful Venus!).
Then follows the Earth’s orbit and then all the rest. Mars
is a little way out there and the others are WAY out there!
The most beautiful of our views of the planets is what is mistakenly called the
“evening star.” It’s a planet, usually Venus, but often Mars, and
rarely Saturn or Jupiter. Same with the “morning star.” Why is this?
First, Venus, being between the Earth and the Sun, is always low in our
sky, that is, it never swings around the night, or dark, side of the Earth, but dipping into our view in the evenings shortly after sundown
and in the mornings shortly before sunup (I use those terms popularly,
of course, the Sun certainly doesn’t “come up” or “go down,” it is the Earth
which "rotates" from … but you remember). And Mars, whose orbit swings
completely around the Earth, is most often somewhere other than dipping
into our evening or morning sky, got it? Saturn and Jupiter, slowly
advancing across the heavens, are even less often seen in these evening
or morning positions,
being mostly high overhead in the darkest of night when we see their full face
reflecting the Sun from behind the back of our Earth.
Yes, compared to the stars, the planets fairly dance! They are putting
on a show that they want us to watch and we are their audience.
* * *
In the year, 2000, our little organization moved into a big, three-story
building on the circle road around Oaxaca, with a wide-open roof at the
top of broad stairs, where we set out some tables and chairs and often
enjoyed a beer in the evenings and watched the skies do their magic. I
liked to point out the planets to my friends and explain a little of their orbits and
when greeted with puzzled looks, I would often quickly sketch out what we were
looking at. Here are a few of those sketches.
Below, a very special view of four planets on the same evening; a rare
and brief view of Mercury low to the horizon, Venus swinging rapidly
toward us in her little, tight orbit, Mars slowly rising from her swing
around the sun, and Jupiter, far out there, inching slowly upward. I
am explaining it to Felipe. He doesn't quite get it.
Below, as I explained to Dottie, the Moon, in its tight little orbit
around the Earth, reflects the setting sun and shows us a perfect "half-Moon"
at the moment it crosses our own Earth's orbit and is exactly
"perpendicular" to the Sun's rays. She got it right away.
Here I am, explaining to my friend, Jesús, outside our condom store on
Mier y Teran street, just why the Moon is still in its first quarter,
namely that it hadn't yet crossed over the orbit of the Earth. He
said, "¡Güau!" (pronounced "Wow"). (You also might like to notice
that our little store had just sold its 12,655th condom!
Below, another of those rare sightings of Mercury. Looking due
west from our condom store on Trujano street shortly after sunset on the
11th of March, the little planet could be seen briefly near a thin
cresent Moon. The followinging evening, the 12th, was cloudy.
That's a little bit of the piramids we can see atop Monte Albán to the
south. Felipe said, "Time to eat!"
Here's a morning view, shortly before sunrise, looking east and "forward"
in our Earth's orbit, and showing where we'll be in three months, and
again in six months. Note that Mars' orbit, further out, is slower
than the Earth's and, though both are moving in the same direction, the
Earth will slowly "pass" Mars and Mars will appear each night a little
further to the west, thereby appearing to move "backward" in its orbit.
On September 2nd, Venus appeared even higher in the sky than Jupiter.
I explained that Jupiter was way past Venus and as Venus tears toward us,
rising in the evening sky, the Earth in its orbit was leaving Jupiter
far behind to sink lower and lower into the west each night.
Below is a different kind of sketch which combines in the same drawing
two views, an early morning view
looking east, on the right, and an evening view looking west, on the
left. We can see our Earth's orbit, looking
forward to where we're going, in the morning, and backward to where
we've been, in the evening. And we can also see Venus' orbit,
within the Earth's, and watch as Venus moves from our morning views,
travels around the far side of the Sun, and emerges a short time later,
usually a month or so, to be our beautiful "evening star." Mars is
Below, the right side of the above drawing shows our view shortly before
dawn, looking east.
And below, from the left side of the above drawing,
the evening view, looking west.
So I hope these little sketches will be some small help, my friends,
when you look up into the beautiful, evening sky, that you might see all
the little arrows and orbits and directional signs and remember, with
Felipe and Dottie and all your friends down here in Oaxaca, that the sun is not "going down"
or "coming up," but that our own, little, round planet which
is called Earth is "rotating" on its
axis and "revolving" in its orbit around the Sun. It's a little
tricky, but you can do it!
* * *
...NEXT BOOK: Bill
Wolf's COMPUTER SKETCHBOOK