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.
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