Skylights featured five times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
, 5
Photo of the Week.. In the first of a short series,
a thunderstorm, illuminated by a setting Sun and seen from an
aircraft flying at the same altitude, roils away against the blue
of a distant sky.
Astronomy news for the week starting Friday, July 15, 2005.
A month after the passage of the Sun
over the Summer Solstice, the
Moon passes its full phase the
night of Wednesday, July 20th, about halfway between the classical
figures of Sagittarius and Capricornus, not quite as far south as
last month's full Moon but close, since (because of the lunar
orbital tilt) the full Moon will be rather well below the ecliptic. Prior to full, watch
as the waxing
gibbous, rising ever later, descends ever deeper to the south,
passing through Scorpius and near
Antares the night of Sunday the
17th.
In North America, the full phase actually takes place about moonset
the morning of Thursday the 21st, when it will set at sunrise. The
night of the 20th thus finds our neighbor just short of technical
full, causing it to rise a bit before sunset. Only nine hours past
full, the Moon passes its perigee,
where it is closest to the Earth, producing one of the angularly
largest full Moons of the year. The effect, while photographable,
cannot be seen with the naked eye. That the rising Moon looks very
large is strictly an optical illusion, indeed is called "the Moon illusion."
The western evening sky still intrigues. Though Saturn is
gone, and will soon (next week) pass conjunction with the Sun, and
though Mercury
has dropped nearly out of sight, Venus
climbs yet higher and is now obvious in the western twilight sky
just a bit to the north of due west. As the week proceeds, Venus
moves easterly against the stars at the same time the
constellations slip to the west, causing Venus and Regulus in Leo to approach each other, the pair coming into nice
conjunction on Friday the 22nd. On a larger angular scale, Venus
and Jupiter (Jupiter in Virgo to the west of Spica) slowly approach as well, the
giant planet nicely visible in the southwest in early evening and
not setting until around midnight Daylight Time (making it fully an
evening object). Half an hour after Jupiter sets, Mars (in Pisces) rises, the red planet best viewable in the
later morning hours.
This is the season to admire great Scorpius (the figure looking for
all the world like a giant scorpion), best visible now to the far
south around 10 PM Daylight Time, though the bright Moon will for
a time make it rather difficult to see in all its detail. Less
known in the northern hemisphere is a bright, beautiful
constellation to the southwest of Scorpius, Lupus (the Wolf), which connects nicely with Centaurus (the Centaur), which lies
even farther to the southwest, and which in turn lies to the north
of one of the most famed figures of the sky, Crux, the Southern Cross.
