[net.astro] StarDate: December 1 Spica and Mars

dipper@utastro.UUCP (Debbie Byrd) (12/01/85)

The planet Mars is near the star Spica in the morning sky.  More --
after this.

December 1  Spica and Mars

The planet Mars is now near a bright star on the dome of the sky --
high in the southeast before dawn.  The star is Spica, the brightest
light in the constellation Virgo.  Mars and Spica will appear about
three degrees apart Monday morning.  That's about six times the
diameter of the moon.  Spica will be brighter than the dim reddish
point of light that is Mars.

Spica is a lot farther away from us than the planet -- about 275
light-years distant, as compared to light-minutes for Mars.  But Spica
is intrinsically a very brilliant star.  If we could line up Spica and
our sun at the same distance away, Spica would appear about
twenty-three hundred times brighter.

But Spica is actually two stars -- whose centers are separated by only
eleven million miles -- about a twelfth of the distance between Earth
and the sun.  The two stars revolve around each other every four days.

The closest that the Earth and Mars ever get is about thirty-four
million miles.  Mars is much farther away than that from the Earth
right now -- but the distance between the two worlds is decreasing.
Earth is gaining on Mars in orbit around the sun -- and will catch up
with the desert planet this summer.  In July, our world will rush
between the sun and Mars -- for an excellent "opposition" of Mars in
which it will be closer to Earth than it has been for more than a
decade.

Again, you can see Mars tomorrow morning.  It will be the reddish
object within six moon diameters of bright Spica -- high in the
southeast before sunrise.

Script by Diana Hadley.
(c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin