SKYLIGHTS
Astronomy news for the week starting Friday, February 9, 2001.
The Moon, now past full, fades from the evening sky. At first
waning through its gibbous phase, it passes third quarter the night
of Wednesday the 14th shortly before Moonrise in the Americas, and
then enters its waning crescent phase. The morning of Thursday the
15th finds the Moon just to the north of Mars, the pair just short
of encountering the three-star head of Scorpius.
Mercury and Uranus make an odd pair this week, as both go through
conjunction with the Sun, Uranus on Friday the 9th, Mercury on
Monday the 12th. The two could not be more different. Mercury, an
"inferior planet," one closer to the Sun than we are, passes its
"inferior conjunction" as it goes roughly between us and the Sun.
Half an orbit later (as viewed from Earth) it will pass its
"superior" conjunction," when it is on the other side of the Sun
from us. Uranus, on the other hand is a distant "superior planet"
that is outside the Earth's orbit. Its conjunction is always on
the other side of the Sun. When the Earth swings through half an
orbit (as viewed from Uranus), Uranus will then pass opposition
with the Sun, when the two are opposite each other in the sky.
Though both are in solar conjunction, Mercury is moving westward
against the stars, retrograde, whereas Uranus is moving in its
normal direction, eastward. They could hardly be more different
physically, either: Mercury is less than 40 percent the size of the
Earth, cloudless, and made of iron and rock; Uranus is four times
Earth's size, 15 times its mass, is covered with methane clouds and
haze, and is made of hydrogen, helium, water, and other light
stuff. Unfortunately, the solar glare will make viewing them
impossible.
We CAN, however, easily view brilliant Venus, high in the
southwestern sky at twilight, and still brightening, as well as the
still-close pairing of giant Jupiter (the brighter) and Saturn,
high to the south in early evening, both still set within the
confines of Taurus (not to mention the morning appearance of Mars,
which is now rising around 1:30 AM).
The polar sky begins to turn our thoughts toward spring. At 8 PM,
Perseus is nearly overhead or to the north for most in North
America. While Cassiopeia falls to the northwest, and the Little
Dipper rides beneath the pole below Polaris, the Big Dipper in Ursa
Major begins its majestic rise in the northeast, led by the four-
star "Bowl." Watch as it climbs ever higher as the Earth rounds
the Sun and the seasons advance. To the south, Orion the Hunter
still dominates, below him a distorted box that makes Lepus the
Hare, and below that the small flat triangle of Columba, the Dove.
