Astronomy news for the week starting Friday, April 30, 1999.
We begin the first week of May with the Moon passing through full,
the exact phase occurring a few hours after moonset the morning of
Friday, April 30, the Moon rising just past full that night. The
following day, the Moon passes its apogee, when it is farthest from
the Earth, rendering "spring tides" (that take place at new and
full moons) lower than usual.
Saturday, May 1, marks the closest approach by Mars to the Earth
(86.5 million kilometers, not quite six-tenths the distance between
the Earth and the Sun) for this synodic period (viewing cycle) of
2.14 years. The planet is also at its brightest now, very nearly
the apparent brightness of the sky's brightest star, Sirius, though
of different color. People differ in their perceptions of star and
planetary colors. Some see Mars as noticeably red (the color
coming from iron oxides in the Martian dust), while others see it
more yellow-orange, a sort of soft "butterscotch." Try it
Saturday, May 1, "May Day," is also a special day for the Earth and
its orbit, as the night before, May Eve (Friday, April 30) is a
"cross-quarter day" that marks the halfway point between solar
passages of the vernal equinox in Pisces (the first day of spring)
and the summer solstice in Gemini (the first day of summer), the
Sun now within the confines of Aries, passing south of the
constellation's classical figure. Other cross quarter days are
Groundhog Day (Candlemas) on February 2, Halloween on October 31,
and Britain's Lammas Day on August 1, a harvest celebration.
Saturn is gone from the visible sky and Jupiter hard to find in
early morning twilight. Uranus and Neptune, both set against the
stars of Capricornus and rising about 2 AM, might stand in for them
except that dim Uranus is only barely visible to the naked eye and
dimmer Neptune requires large binoculars. Neptune, however, makes
a bit of news as it becomes "stationary" on Thursday the 6th,
beginning its retrograde motion as the Earth prepares to swing
between it and the Sun.
With the Sun in Aries, its opposites in the zodiac, Virgo and
Libra, ride the sky at midnight (1 AM daylight time). Look for
Spica a bit to the west of the meridian and for orange Arcturus
high to the south, its color similar to that of brilliant Mars,
which lies below it.