SKYLIGHTS
Astronomy news for the week starting Friday, July 2, 1999.
We begin the week with the Moon approaching its last quarter, the
phase reached on Tuesday, July 6, just about the time of sunrise
when the quarter Moon is to the south, the waning phases darkening
the sky once again. The mornings of Wednesday the 7th and Thursday
the 8th, the Moon will make attractive configurations with Jupiter
and Saturn, which are now in full and easy visibility to the east
at dawn. On the morning of the 7th, the Moon will be to the right
of Jupiter, on the 8th to the right of ringed Saturn, the two
planets slowly drawing closer to each other.
In the evening, Venus still shines brilliantly to the west at
sundown, the second planet from the Sun still increasing in
brightness as it is slowly being overtaken by the Sun. Contrast it
with reddish Mars, which shines brightly in the southwest, the
planet's motion relative to the star Spica (to the right of Mars)
now increasingly obvious.
Pluto now lies due south at 11 PM daylight time in the large
constellation Ophiuchus 16 degrees due north of bright Antares in
Scorpius. Though you cannot see Pluto without a good-sized
telescope, at least you can think about it and know where it is.
Its high angle of inclination to the plane of the Earth's orbit is
has taken it well above the ecliptic, the apparent path of the Sun.
Ophiuchus, a huge distorted pentagon, is entwined with a great
celestial serpent, Serpens, the only constellation in the sky
broken in two separate parts.
Finally, Earth makes news at it passes aphelion, its farthest point
from the Sun, on Tuesday, July 6 at 5 PM CDT when it will be 152.1
million kilometers (94.5 million miles) from the Sun, 1.7 percent
farther than average. That aphelion takes place during the height
of northern summer shows that Earth's distance from the Sun has
little to do with the seasons. We are now actually receiving 3.4
percent less radiation from the Sun than average. Since aphelion
and perihelion respectively occur during southern hemisphere winter
and summer, the southern hemisphere should have more extreme
seasons than the northern, but the effect is lost in the
distribution of the moderating oceans. The effect is quite strong
on Mars, however, which has a bigger difference between perihelion
and aphelion distances and also no oceans.
