Photo of the Week. The ghostly
Ring Nebula in Lyra, M 57, was formed by the ejecta
from the dying star in the middle. While there are many far-more-
magnificent
images of the famed "planetary nebula" (a misnomer,
meaning merely "disk-like"), this is much the way it looks in an
amateur telescope. (University of Illinois Prairie Observatory.)
Astronomy news for the week starting Friday, February 16, 2007.
On Saturday, February 17, the Moon once again
begins its monthly round with its new phase, as it has for more
than 50 billion times since it was born in what was probably a
giant collision of a small planet with the primitive
Earth. No one really knows, but it is the only theory that
seems to work and to explain the lunar characteristics, especially
the severe lack of iron.
Look for the debut of the familiar slim crescent low in western
twilight the night of Sunday the 18th, when it will first be
visible. The following twilit evening, though, that of Monday the
19th, you won't have to seek the Moon out, as it will be prominent
just above brilliant
Venus, the two making a near-classic pairing. Even the night
of Tuesday the 20th they will still make a nice sight in the
evening sky. Wait until the heavens darken a bit so you can admire
Earthlight on the lunar nighttime
side, that facing away from the already-set Sun. Though the Moon
will look near new to us, from the Moon, the Earth will be near
full, and will brightly illuminate the lunar landscape. As the
crescent fattens, Earthlight fades away.
The remainder of the planetary night belongs to the two giant outer
planets, Saturn
and then Jupiter.
Just past opposition to the Sun, the ringed planet is already risen
by sunset and is well up in the east by the time the sky darkens.
To the east of it lie Regulus and
then the rest of Leo. Saturn
transits the meridian high to the south
and sets just before sunrise. For a time after Jupiter rises
around 2:30 AM, they share the sky. Far to the south of the
equator, Jupiter resides just to the east of Antares in Scorpius, and can be seen approaching the meridian to
the south as twilight brightens the morning sky. Mars,
well to the east of Jupiter, remains difficult to find, as it does
not rise until dawn begins. The other planets are even more out of
sight.
The beauty of the winter sky is in part due to great Sirius, the brightest star in our
sky. Far from the most luminous (that honor going to the southern
hemisphere's Eta Carinae), it
seems so lustrous mostly because it is quite close to us, a mere
8.6 light years away. The star stands at the top of one of the
most prominent of constellations, Canis
Major, the Larger Dog. Quite overwhelmed by Sirius is the
faintest of the first magnitude stars, Adhara (Epsilon Canis Majoris), the
brightest of a prominent triangle seen toward the south. Much
farther down from Sirius, and visible only south of about 35
degrees north latitude is Canopus, Alpha Carinae, the second
brightest star in the sky, one that side by side would shine vastly
brighter than Sirius.
