Last July’s reckless tryst between Jupiter and comet Shoemaker- Levy recalled the exciting violence of the early solar system, the old days when sparks flew from worlds in collision.
Jupiter, the most intricately detailed planet, hardly needed outside help to be a fascinating object. But the pummeling by airport-size comet chunks created a riveting witches’ brew of dusty debris and dredged- up ammonia from the Jovian clouds. The ensuing black patches looked like missing pixels caused by some computer glitch.
Those ominous impact blemishes would have kept amateur and professional astronomers glued to their instruments all winter, but they were relegated to other obsessions when the giant planet slid behind the sun to be lost for months in the solar glare. Now it’s back. This month Jupiter reaches opposition--when it’s closest to Earth and out all night. No question: May through July offers the best opportunity in 1995 for examining Jove.
It all starts with finding the planet, a no-brainer: Jupiter is the night’s brightest star. Best after 10 P.M., it dazzles the south near dimmer, orange Antares. Jupiter’s 12-year orbital period causes it to spend a year in each of the dozen zodiacal constellations. But tradition has overlooked Ophiuchus (oh-fee-YOU-kus), a thirteenth constellation that the sun and planets routinely visit. (If asked your astrological sign, say you’re an Ophiuchan!) Jupiter begins the month and spends most of the year in that forgotten member of the zodiac. (This southerly precinct, in which Jupiter will linger until 1998, is the zodiac’s lowest branch for North Americans.)
Are Jupiter’s scars still visible? And what’s the best way to look for them? The first requirement is patience. Persistent staring makes detail emerge as if by magic, which is why some amateurs said they could not see a thing last summer whereas experienced observers raved.
So if Jove is a new friend, expect its features to appear as slowly as in a photographer’s darkroom. You’ll first notice its oval disk, blank and gratifyingly large. Just 120 power, a good magnification in most telescopes, makes Jupiter appear three times larger than the moon looks to the naked eye!
Dark belts quickly materialize. Much more challenging are the white ovals that rotate in and out of view as they follow Jupiter’s frenetic ten-hour spin. Observing the dark, comet-induced spots last year meant waiting for them, too, to rotate into sight. But now they have merged, like the spin art at carnivals, into a single dark band south of Jupiter’s equator.
Since telescopes invert the image, the newly minted comet belt lies near the top of the planet. Don’t mistake it for the wide equatorial bands straddling the middle, the result of material rising or falling through the frozen violence of Jovian clouds.
Astronomers had hoped the comet fragments would thrust up material from deep below the clouds. Instead they exploded shallowly, denying us visions of the Jovian nether world. But the blasts did create compounds never seen there before. According to French researchers, impact heat generated at least 200 million tons of carbon monoxide, a serious violation of federal emissions standards.
Even though Jupiter is keeping its secrets to itself, you can count on the planet’s dramatic appearance as summer’s most brilliant midnight star. Too bright to ignore, it should catch the eye of anyone glancing up into the heavens.