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A Parade of Planets

During much of October and November 1997 a very unusual circumstance occurs: all the planets are above the horizon at one time for a while after sunset! Actually, dim Pluto is too low in bright sky during these months for anyone to see, and you need binoculars and detailed finder charts (like those in Sky &Telescope magazine's May issue) to locate Uranus and Neptune. A wonderful feat to try in mid-to-late November, however, is to see all five of the classic naked-eye planets at one time. Mercury will be the hardest to see, a bright point of light but one that appears very low in the west-southwest before dusk is over.

The other four bright planets are easy to spot as long as your view of the southwest sky is not obstructed. Low in the southwest for a few hours after sundown are Venus, brightest point of light in the sky, and Mars, much fainter but forming a close companion with Venus week after week. Jupiter is the second-brightest planet and is fairly high in the south at nightfall. Saturn is the brightest object rising in the east at nightfall these months.

Our Almanac table lists the many, many arrangements of these planets with each other, with the Moon, and with the stars. Something to bear in mind is that the separations in "degrees" can be estimated in a simple way: your fist held out at arm's length is about 10 degrees wide. Most of the sights are easily visible to the naked eye, but two of the most remarkable do require a telescope. They are the hiding of a star by Jupiter on November 12 and the "grazing occultation" of Saturn by the Moon on November 11. The "graze" occurs when Saturn and its rings pass right along the edge of the Moon so that they are partly visible behind lunar mountains and valleys for several minutes. The graze will only be visible in a band several dozen miles wide, running from southern Texas to southern New Jersey and Cape Cod (south of the band Saturn goes completely behind the Moon; north of the band it is a close miss).

Another astronomical event to look for is the Leonid meteor shower, zooming from the southeast in the hours before dawn on November 17. It is next year and 1999 that the passage of the Leonids' parent comet may cause this annual display of shooting stars to burst into a "meteor storm," thousands of meteors per hour, as seen from some parts of the world. But last year there was a remarkable display of almost entirely very bright Leonids. In a single 20-minute period I saw two Leonids bright enough to light up the landscape and cast shadows, and the trails left by them remained visible to the naked eye for several minutes. If a similar display occurs this year, not even bright moonlight will severely diminish its splendor.

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