SKYLIGHTS
Astronomy news for the week starting Friday, February 18, 2000.
The Moon passes full this week on Saturday the 19th, and will then
spend the rest of the week waning through its gibbous phase. Full
phase will actually be reached in the morning in North America,
when the Sun is up and the Moon is not visible. As a result, the
Moon will be somewhat past full at moonrise that evening, and will
rise slightly after sunset. Because the next full Moon will take
place in Virgo only three hours before the Sun crosses the vernal
equinox in Pisces, this full Moon be in the next constellation to
the west, in Leo, just to the south of the bright stars that make
the classic figure.
As spring approaches, the two giant planets of the Solar System,
Jupiter and Saturn, while moving easterly against the stars and
drawing ever closer, are displaced ever more each evening to the
west as a result of the Earth's motion around the Sun. The only
other evening planet, Mercury, begins the week barely visible in
western twilight. But it rapidly fades from view as it enters its
retrograde, or westerly, motion against the stars on Sunday, the
20th. The next two planets outward, Uranus and Neptune, are now
beginning to clear the morning Sun. Neptune, to the west of
Uranus, is first, and comes into conjunction with (and only half a
degree to the north of) Venus the morning of Tuesday, the 22nd.
Though both are moving easterly against the stars, Venus is
catching up with the Sun, while Neptune is pulling away from it (as
seen from our Earthly vantage point).
By 9 PM, Canis Major (the Larger Dog), with the sky's brightest
star, Sirius, begs from the southern part of the meridian.
Wrapping around it from the east to the south is a set of bright
southern stars that make part of Argo, the great ship of Jason and
the Argonauts. Seen in full only from southerly latitudes, Argo is
so large that astronomers of the late nineteenth century broke it
up into three parts (fortunately not sinking it): Puppis, the
Stern, Carina, the Keel, and Vela, the Sails. The most northerly
portion, made from the stars closest to Canis Major, are part of
Puppis. Vela is southeast of Puppis, and Carina, far to the south,
holds the sky's second brightest star, Canopus, seen only from
latitudes south of about 35 degrees north. Just to the east of the
bright stars of northern Puppis, about the same distance below the
equator as southern Canis Major (and visible from most of populated
North America), is a faint modern addition to the ship, Pyxis, the
Mariner's Compass, carved in the seventeenth century from those
that once represented the Ships's mast.
