Photo of the Week. A turbulent cloud coils across the
sky; see another view.
Astronomy news for the week starting Friday, November 3, 2006.
The Moon begins the week in its late waxing
gibbous stage as it heads toward full on
the morning of Sunday, November 5, just about the time of Moonset,
which takes place almost exactly at sunrise. A day before full, it
passes perigee,
where it is closest to the Earth,
giving us slightly more full Moonlight than average. The Moon will
thence wane in the gibbous phase over the rest of the week, sadly
not visiting any of the planets, though it will make a fine sight
as it plows through Taurus the
nights of Monday the 6th (east of the Pleiades) and Tuesday the 7th.
What we do have is an excellent and rather rare visit between Mercury and the
Sun. On Wednesday, November 8, the planet passes inferior
conjunction with the Sun, where it is in between the Sun and us.
Because of the tilt of the planetary orbit, Mercury is usually not
QUITE aligned, but passes either above or below the solar disk.
This time, however, the planet passes right across the Sun for a
"
transit." Transit seasons are early November and May. November
events are separated by intervals of 7 or 14 years. May
transits (which take place with the planet farther from the
Sun) are rarer, and can, but don't have to, recur in 14 years. (Transits of
Venus are far rarer. There were none in the twentieth century;
the last one was in 2004, the next in 2012.) Transits of Mercury
are NOT visible to the naked eye, even with appropriate filters,
but are readily visible with the telescope. However, they should
be viewed by projection only; do not even try without professional-
level knowledge or help. The event begins at 1:12 PM CST (2:12
EST, 12:12 MST, 11:12 AM PST, 9:12 AM Hawaii), and lasts for about
5 hours as the planet slowly moves in orbit. Only the western US
and Canada will witness the whole thing before sunset. The timings
of such transits were once used in attempts to establish local
times and thus longitudes.
The only other bright planet visible to us now (the others lost in
twilight) is Saturn, which
makes a transition to evening this week, rising at or just before
midnight local time. By dawn it is high in the southeast to the
west of Regulus in Leo.
As autumn and evening roll on, we see more of the great
constellations of the Perseus myth. Well to the north are the "W"
of Cassiopeia and the star-streams
of Perseus, while well to the south
are the fainter stars of the villain of the
story, Cetus, the Whale or Sea
Monster, his tail now crossing the meridian around 10 PM marked
by rather bright Deneb
Kaitos, his circular head crossing two hours later. In the
middle lies the prototype of the long-period Mira variables, Mira itself.
