Sister planet. Nearest neighbor. Goddess of love. How appealing Venus sounds! But the strange cloudy world is actually a land of paradox and horror. And this is the best time to watch it. by Bob Berman DURING THE FIRST months of 2001, North Americans will have their finest look at Venus in years. Like a UFO, it will grab the attention of and bewilder onlookers as it hovers with fantastic brilliance in the evening sky. When Venus reaches its greatest elongation (widest angle from the Sun) between January and March, the evening star is as high and prominent as possible. This optimal state of affairs occurred in 1993, and it happens again in 2001.
At greatest elongation, Venus and the Sun are maximally separated-by 47°. This can allow the evening star to be seen several hours after sunset against a black night sky. The eight-year interval is no fluke. Venus completes 13 orbits of the Sun in exactly the same time Earth makes 8. So after eight years, our sister planet returns like a meshed gear to the same observational situation. The year 2001 starts with the evening star already prominent at dusk. As January progresses, Venus rises even higher, achieving its widest separation from the Sun -- 47 degrees -- on the 17th, and then its greatest brilliancy a month later on February 21. But a lofty twilight perch and visibility for hours after sunset is only part of the majestic 2001 winter's tale.
At greatest brilliancy in late February, Venus will shine luminously above the western horizon. Nearly as reflective as a mirror, Venus is the shiniest planet. Fully 76 percent of the sunlight striking its white sulfuric-acid clouds gets bounced away. Several factors now combine to make it even brighter. During the last week of February, Venus arrives at its closest point to the Sun, which floods it with the most intense possible lighting. At the same time, its increasing nearness to Earth brings it to a maximum brightness -- "greatest brilliancy" -- in our sky. Topping it all off, Earth, in its own elliptical path, is then just a few weeks past its yearly close approach to the nearly circular Venusian orbit, placing both worlds unusually close together. It all adds up to offer us an extraordinary visual treat, when Venus attains its high, prominent perch at a convenient early dinner hour. And still the show's not over. From February to late March, Venus sinks lower at dusk as it prepares to pass between us and the Sun. During this time, steadily braced binoculars reveal a striking crescent. Any telescope, any magnification, makes it seem dreamlike, a strange featureless "moon" that appears larger and skinnier each March evening. Then comes the kicker. On March 29, Venus passes between us and the Sun. (But not exactly between: That event will happen in June of 2004, a spectacular transit of Venus across the face of the Sun, which hasn't occurred since the 19th century.) This time around, Venus scoots far to the north of the Sun, granting more rewards to Northern Hemisphere inhabitants. Normally Venus is east or west of the Sun; now it's suddenly 10 degrees due north. This allows the planet to perform the seemingly impossible feat of setting after sunset but also coming up before sunrise. Because all these shenanigans involve the night's brightest "star," the dazzling show will be witnessed by billions of people. Most will not know that they are viewing our neighboring planet at its best. It's touching that we named the most luminous "star" after the love goddess. It's sweet that the evening star's similar-to-Earth size suggests a sister world. But we'll never have a hands-on relationship. For all eternity, the nearest planet -- that dazzling beacon in the west -- will tantalize with a warning label: Look but don't touch.
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Few who gaze longingly at the glowing beacon in the western sky are aware of Venus's oddities.
