Skylights featured five times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
, 5
Photo of the Week.. Soar like an eagle (or maybe a
seagull) in a perfect blue sky.
Astronomy news for the week starting Friday, July 19, 2005.
The week begins with the full
Moon, the phase reached about noon on Friday the 19th. By
Friday evening, the Moon will be a few degrees to the east of the
point opposite the Sun,
just beginning its waning gibbous
phase, and will rise just after Sunset. During the remainder
of the week it will continue to wane toward the third quarter,
that phase reached next Friday the 26th, again during daylight
hours. On Saturday the 20th, the Moon will pass a couple degrees
south of Uranus, while on Wednesday the 24th it
will make a far grander passage to the north of Mars, the two about
six degrees apart as seen in the nighttime sky. The following
night, on Thursday the 25th, look for the Moon near the Pleiades cluster in Taurus, the rising of the "Seven
Sisters" a hint that fall will soon be in the air and winter not
far behind.
By the time Mars rises, around 11 PM Daylight Time, it is the
only one of the ancient planets to grace the sky, as well as the
brightest body to be seen other than the Moon itself. As it slowly
approaches opposition with the Sun next November 7, it continues to
brighten, and in the stellar realm is topped only by Sirius. Note that there is a rumor
circulating in cyberspace that on August 27 Mars will be at its
closest in some 50,000 or so years. Pay no attention. It is a
news release from two years ago that has taken on a life of its own
and refers to August 27, 2003! During this year's closest approach
on October 29 (which because of the ellipticity of the Martian
orbit does not quite coincide with opposition) Mars will be 0.464
Astronomical Units (70 million kilometers, 43 million miles) away,
0.091 AU farther than it was at the 2003 approach. The culprit is
again
orbital eccentricity, which takes the planet on a 17 year cycle
of varying distances from Earth at successive oppositions (which
average 2.1 years apart).
The early evening on the other hand belongs to Jupiter
and Venus as
the two approach each other for a conjunction on September 2, both
visible in western twilight, Venus the brighter and lower of the
two, Jupiter still to the west of Spica in Virgo. The separation between the pair is visible from
night to night. In parallel, morning twilight holds Saturn and Mercury, the latter (below
Saturn) reaching greatest western elongation on Tuesday the
23rd.
By 9 PM Sagittarius, the most
southerly of the zodiacal
constellations, is nicely visible to the south, the view better
once the Moon is out of the way. To the right is Scorpius, to the north the modern
constellation Scutum (the Shield),
while below it lies the graceful curve of Corona Australis, the Southern Crown.
