Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. Stars rise against the dramatic
background of a chateau in the Perigord Region of Southern France.
Polaris is at far upper left. The
three bright stars diagonally down and to the right of Polaris are
Deneb, Vega, and Altair of the Summer Triangle. (Photo courtesy of Greg Dimijian; 3.5
hour time exposure taken 8-9 June, 2004, with an f/2.8 fisheye lens
on Provia 100 film.)
Astronomy news for the two-week period starting Friday, July
16, 2004.
This extended "travel" version of Skylights covers the next two
weeks. Skylights will resume its normal weekly schedule on Friday,
July 30.
We begin the fortnight with the Moon just barely shy of new, the
phase reached on the morning of Saturday, July 17, just about the
time of Sunrise (and of course, given the new phase, Moonrise).
The interval to evening is too short to allow the waxing
crescent to be seen that Saturday night, but watch for it in
twilight the evening of Sunday the 18th. Climbing higher in the
sky each night, the Moon waxes to first
quarter the evening of Saturday the 24th around the time it
sets in the west. During the following week it waxes through gibbous to
full, the phase reached at the end of the month after Skylights
resumes its usual pace.
Let the Moon be a guide to the planetary sights of twilight. The
evening of Sunday the 18th finds the slim crescent just to the
right of Mars,
which is finally disappearing from view. Bright twilight makes the
planet impossible to see without binoculars. Farther to the left
of the Moon, past Mars, lies much brighter Mercury, which is advancing on the nightly scene
toward its greatest eastern elongation relative to the Sun on the night of
Monday, the 26th, when it will be at its best for this apparition.
The low angle of the ecliptic to the horizon, however, will still
make the planet difficult to see. On the night of Monday, the
19th, the crescent will stand directly above the little planet,
again allowing one to find it -- binoculars are really needed.
That same night, look for the star Regulus in Leo just to the left of the Moon. On the night of
Sunday, the 25th, Mercury and the star come into conjunction with
each other, standing only 1.5 degrees apart (Mercury the brighter
of the two).
The nights of Tuesday the 20th and Wednesday the 21st the Moon
brackets Jupiter, the
Moon to the west of the planet on the 20th, to the east on the
21st, not that one needs the Moon to find the brightest non-lunar
body of the evening sky. For a brighter planet, look to the east
as dawn begins for brilliant Venus, which will keep getting
higher in the pre-dawn sky until mid-August.
As twilight ends, one of the sky's great constellations, Scorpius, the Scorpion, dominates the
southern sky as it crosses the meridian. Scorpius rivals Sagittarius as the most southerly zodiacal
constellation. From the Tropic of Capricorn to below 40 degrees
south latitude, parts of the constellation shine from nearly
overhead, the Scorpion's glories including bright clusters and one
of the finer portions of the Milky
Way. Just to the north of it is the huge figure of Ophiuchus, the Serpent Bearer, who
is wrapped with Serpens. the
Serpent. The border between Ophiuchus and Scorpius marks the
location of dark dusty clouds in the Milky Way, which together
contain one of the great nearby star-forming regions of the
sky.
