SKYLIGHTS
Astronomy news for the week starting Friday, June 9, 2000.
We have another week with no quarterings of the lunar orbit. The
Moon went through its first quarter on Thursday, June 8, and will
pass full next Friday, June 16, so the during Skylight's entire
week, the Moon will be in its waxing gibbous phase, getting ever
brighter and blotting out more and more stars.
The week, however, belongs not to the Moon but to the two inferior
planets, Mercury and Venus, so called from ancient times because
they are "below" the Earth, that is, between the Earth and the Sun.
Those outside our orbit, "above" the Earth from Mars on out are the
superior planets. Little Mercury passes its greatest eastern
elongation, when it is 24 degrees to the east of the Sun, on Friday
the 9th, and for a very short period will be at its best for
viewing. Look for a bright "star" low in the west-northwest in
evening twilight below Castor and Pollux in Gemini. Mercury is so
close to the Sun that it is never seen in full darkness. If
Mercury is at his best for viewing, Venus is at her worst. This
nearest of all planets passes superior conjunction with the Sun on
Sunday the 11th. Each of the inferior planets goes through two
kinds of conjunction, once between us and the Sun (inferior
conjunction) and again on the other side of the Sun (superior
conjunction). Venus now moves from a morning to an evening object,
though it will be next month before it becomes readily visible in
evening twilight. In the morning dawn sky, look for Jupiter and
Saturn, the giant of the Solar System now to the east of the Ringed
Planet.
By 10 PM, two first magnitude stars, Arcturus and Spica, ride the
meridian high in the sky, Arcturus the more northerly of the two.
The pair, separated by about 30 degrees, provide a fine color
contrast as a result of very different temperatures, Arcturus
(about 4000 degrees Celsius at its surface) an orange giant star
and Spica (20,000 Celsius and actually double) a pale blue-white.
Arcturus and its parent constellation Bootes (the Herdsman) are
surrounded by celestial monuments to women. To the west of
Arcturus find the sprawling cluster Coma Berenices (Berenices Hair,
testimony to an ancient queen) and to the east Corona Borealis (the
Northern Crown, which honors Ariadne). To the south is Virgo (the
Virgin), which contains Spica. Other feminine figures include
northern autumn's Cassiopeia (the Queen) and her daughter
Andromeda. Often not recognized is the feminine side of one of the
sky's most prominent constellations, Orion, who to the Arabs was Al
Jauza (a womanly "Central" figure of some sort), the name still
ringing in the origins of the names of Orion's two bright stars,
Betelgeuse and Rigel.
