Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. Clouds blow briskly against a
vivid blue sky.
Astronomy news for the week starting Friday, May 14, 2004.
The Moon wanes through crescent
the early part of the week, when it will be nicely visible in the
morning hours as dawn approaches. On the night of Tuesday the
18th, it will pass through new. By the evening of Thursday the
20th, the now-waxing crescent
will grace the sky low above the horizon below brilliant Venus.
The western evening sky gifts us with an unusually nice gathering
of planets. While Venus now settles ever closer to the horizon as
it prepares to swing between Earth and Sun, it still sets an hour
past the end of twilight. To the east, up and to the left of
Venus, is Saturn,
which lies firmly within the confines of southern Gemini. Just to the west of
Saturn, find dimmer
Mars, which recently invaded Gemini as it approaches the ringed
planet for a conjunction between the two on May 24 (when they will
be but 1.6 degrees apart). Notably farther to the east is bright
Jupiter in Leo, which is now
crossing the meridian to the south just about sundown.
Venus also reaches a special point in its orbit, as on Monday the
17th, it becomes "stationary" relative to the background stars and
thereby enters retrograde motion, the event announcing the rapid
disappearance of the planet from the evening sky. By coincidence,
less than a day earlier,
Neptune, in Capricornus, enters
retrograde as well. Of the naked-eye planets, the morning sky
contains but
Mercury, which reaches its greatest western elongation on
Friday the 14th. Unfortunately, the morning ecliptic is rather
flat against the horizon, so the little planet will nearly lost to
morning twilight and be difficult to find at best.
Try also to find Comet
NEAT, which will be up and to the left of Gemini. Binoculars
will help.
The stars of spring now rule the sky, winter's Capella replaced by the bright
orangy glow of Arcturus in Bootes, the brightest star of the
northern hemisphere. The classic way of locating the star is to
follow the curve of the handle of the Big Dipper to the south. Then keep the curve going,
and it will next pass through first magnitude Spica in the constellation Virgo, which contains the autumnal equinox, the point in the
sky where the Sun crosses the celestial equator on its way south to
announce the beginning of astronomical autumn. Spica lies to the
northeast of the distorted box of stars that makes Corvus the Crow, whose two top
stars point back to the Spica much as the two front bowl stars of
the Big Dipper point back to Polaris in Ursa Minor. South of Spica lies the tail of Hydra (the Water Serpent), and
farther south the center of Centaurus. Curiously, Spica is almost exactly south of
Mizar and Alcor in the Big Dipper, and almost
exactly north of the greatest globular cluster in the sky, Omega
Centauri, which is decently visible only south of latitude 35
degrees north.
