SKYLIGHTS
Astronomy news for the week starting Friday, October 27, 2000.
This Skylights is dedicated to the memory of our daughter Jill, who
left this Earth, but not our hearts, on October 26. She too was a
bright star.
The week begins with the new Moon, the phase reached early in the
morning of Friday, the 27th. While by Friday evening the Moon will
be in its waxing crescent phase, it will not be quite "old" enough
to see, and will make its first real appearance the night of
Saturday, the 28th as a slim crescent in the west-southwest. The
night of Saturday the 29th, our silvery satellite will be
attractively seen in twilight to the right of brilliant Venus,
while the following night it will be up and to the left of the
planet (the lunar dark side well-lit with earthlight).
Venus, while growing in glory, still remains rather low against the
horizon, the result of the flat angle of the evening ecliptic this
time of year. That will change as winter approaches, allowing the
planet to climb higher. Venus, closer to the Sun than we are, goes
through a full set of phases quite like those of the Moon. Through
a telescope we now see it in its waxing gibbous phase. Over the
following months, the phase will diminish through "half" to
crescent. At the same time, Venus will continue to close in on us
as it swings around the Sun and will become dramatically brighter.
Its brother planet, Mercury, however, while sort of visible a
couple weeks ago, is now completely out of sight, as it passes
inferior conjunction with the Sun, when it is between us and the
Sun, on Saturday, the 29th. By mid-November, Mercury will be
making an appearance in the early dawn sky.
As the month turns, Jupiter and Saturn begin to dominate the early
evening sky, both well up in the east by 8 PM standard time, both
enhancing the already-bright winter constellation of Taurus. for
now, however, think not of winter but of mid-autumn, whose mid-
evening sky is centered on the Great Square of Pegasus, seen high
to the south around 9 PM. Directly below it is a ring of fairly
faint stars called the "Circlet" of Pisces, which is just up and to
the right of the vernal equinox, the point at which the Sun passes
from south to north as it crosses the celestial equator on the
first day of spring. Nearly everything, it seems, has some kind of
name. The circle in the sky that passes through the equinoxes and
the celestial poles (the northern one marked by Polaris) is the
"equinoctial colure," while its counterpart through the solstices,
where the Sun is as far north or south as it can be, is the
"solstitial colure."
Binoculars will show the left hand and faintest star of the Circlet
to be a bit reddish. This star, 19 (or TX) Piscium, is a fine
example of a "carbon star," one that over the course of its life
has changed its chemical composition as carbon made by
thermonuclear processes has been cycled to its surface. Most of
this carbon will be launched into space by winds, the carbon to be
used by the next generation of stars and planets.
