Photo of the Week.The Sun gently sets through distant
ocean clouds.
Astronomy news for the week starting Friday, February 20, 2009.
The Moon starts us off with its waning crescent phase, which always makes
for a pretty morning sight. The waning crescent ends with the new
Moon on Tuesday, February 24, after which it reverses itself to
appear as a waxing crescent in the early
evening sky. Your last glimpse of the waning version will be in
twilight the morning of Monday the 23rd, while the first sighting
of the waxing crescent might be had, also in twilight, the evening
of Thursday the 26th.
The twilit morning of Sunday the 22nd, the Moon will make a
remarkable, though difficult-to-see, quartet along with Mercury, Jupiter, and Mars, all
running down and to the left. The sight will require a flat, clear
horizon and binoculars. By the following morning, the Moon will
have moved to the other side of the planetary trio. Formal
conjunction between the Moon and Mercury takes place on Sunday the
22nd, as does that with Jupiter, while the conjunction between the
Moon and Mars waits until the next day. On Monday the 23rd,
Mercury then passes about half a degree south of Jupiter. Looking
ahead a bit, so as to prepare, by far the best sight will be the
close pairing between Venus and the waxing
crescent Moon the evening of Friday the 27th.
Venus, of
course, remains a striking sight in western evening twilight.
Still near maximum brilliance amidst the faint stars of Pisces, it stays up until around 9
PM. Vying for attention on the other side of the sky, Saturn, still in
southeastern Leo, rises about two
hours earlier, crossing the meridian
to the south around 1 AM. Through the telescope, the rings have flattened
out and you can see how very thin they are. At the crossing of the
ring plane, they quite disappear from view.
Spotted
Comet Lulin yet? It's visible in binoculars moving to
the northwest between Spica
in Virgo and
Regulus in
Leo. The night of Tuesday the 24th, it will pass south
of Saturn.
We can divide the constellations
into two broad groups, the 48 ancient ones, whose origins are
largely lost to time, and the 38 moderns that were invented largely
between the years 1600 and 1800 (with Argo broken into three giving us a total of 88 accepted
figures). Unique among them is Eridanus, the River, which is a hybrid of the two.
Starting at Cursa (just northwest
of Rigel in Orion), the ancient part of the stream winds west, then
bends south before twisting east then west again, whereupon it ends at Acamar (Theta Eridani). Once the
deep southern stars were seen and mapped, astronomers then added a
"modern" portion that extended
the running river from Acamar to first magnitude Achernar (Alpha Eri), which can be
seen only below about 32 degrees north latitude, which includes the
extreme southern continental US and Hawaii.
