Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. Sun and irridescent clouds
celebrate the late afternoon sky.
Astronomy news for the short week starting Sunday, March 7, 2004.
Our Moon spends the remainder of the week waning through its gibbous phase as it heads toward third quarter
on Saturday, the 13th. As the week ends, it passes perigee,
where it is closest to the Earth in its monthly rounds. With the
Sun approaching the Vernal
Equinox in Pisces, the waning
gibbous will fall well below the celestial
equator, rising in the southeast and setting in the
southwest.
Jupiter and Saturn are working
somewhat in concert. Not long after Jupiter went through
opposition (last week, on the night of March 3), Saturn becomes
"stationary." Ceasing its
retrograde, westerly, motion on Sunday the 7th, it begins
moving back toward the east against the background stars. Jupiter
(to the south of eastern Leo) is
now rising before sunset, while Saturn (high in Gemini) crosses the meridian to the
south around 7:30 PM, just as twilight comes to an end.
Moving rapidly to the east against the starry background as it
slowly falls behind the Earth in orbit,
Mars is climbing
through the northern sky north of the head of Cetus and approaching Taurus, while heading toward a
conjunction with Saturn in late May. Early May will see a nice
gathering of these two planets and Venus in the western
sky following the end of twilight, the latter planet now stunningly
brilliant in early evening.
We commonly divide the sky into thirds. From mid-northern
latitudes, the north polar sky is circumpolar, its stars always up,
neither rising nor setting. Here we find the Big and Little
Dippers, Cassiopeia, and the rest
of the northern crew. From mid-southern latitudes, the sky around
the south pole is visible all the time, and includes famous figures
like the Southern Cross as well as
modern ones not known to northerners like Reticulum, the Net, and Dorado, the Swordfish. From neither location can you
see the others' polar sky. Running between them is the equatorial
sky that is seen from both places, all having access to Orion and his followers as well as
to the stars of summer, from Cygnus
to Scorpius. As we approach the
Earth's equator from mid-latitudes, the number of circumpolar and
invisible constellations diminishes, and at the equatorial circle
they disappear altogether, rendering the whole sky visible.
