At age 46, Galileo was no young kid in 1610. But events that year were destined to change his life - and that of the entire world. They involved the colossal planet Jupiter, which by coincidence is now at its closest and brightest to Earth of the century to date.

When Galileo heard that a Dutch eyeglass-maker had created the first telescope, he was one of the few people who, sight unseen, could duplicate the instrument. Galileo turned his telescope to the sky - and the universe changed. Regarded since ancient Greek times as a smooth body with seas, the Moon was now clearly pockmarked with mountains and craters. The Milky Way's creamy glow burst into untold separate stars: wonder upon wonder.

But it was Jupiter, shining brilliantly in Taurus in January of 1610, that proved the most amazing and controversial. Galileo saw four "stars" lined up alongside the dazzling planet, and watched them change position each night. He realized that they were orbiting around Jupiter.

This - 400 years ago - was no small thing. At the time, Church doctrine bewilderingly insisted that the Earth is the center of all motion. That here was another planet, around which several other bodies circled, degraded Earth's status in an unacceptable way. The stage was set for a life-or-death drama.

As it turned out, Galileo saw no benefits after he quickly published his startling discoveries. Instead, it brought him up on charges, forced him to recant at penalty of being burned at the stake, got him placed under permanent house arrest and left him to die penniless.

Today, anyone can duplicate Galileo's sightings. The cheapest backyard telescope lets us clearly observe Jupiter and its four huge, ever-changing moons, now named the Galilean Satellites in his honor. Indeed, today's worst instruments far exceed Galileo's best telescope, because back in 1610 no one had yet figured out how to get rid of the false smudgy color that plagued the early optics.

There simply isn't a better time to watch Jupiter than now - or a better time to contemplate that astonishing world. Jupiter is large enough to swallow up 1,100 Planet Earths. It spins faster than any other planet, creating horizontal cloud formations, like stripes on a bumblebee.

Few realize it, but Earth has crude cloud belts too. Our Equator is generally cloudy. But 25 to 30 degrees north or south of there bring vast arid zones that include the Sahara and Atacama deserts, and the great dry area of our Southwest and northern Mexico. Going further north or south brings frequent clouds again. Our own horizontal bands are broken, patchy and often overlooked. But Jupiter's frenzied spin - 25 times faster than ours - makes its own dark belts and white zones unrelenting.

With a decent telescope and a steady night when the stars don't twinkle, all this detail springs into view. With white ovals and turbulent boundaries when belts and zones rub against each other, plus the Great Red Spot (which these days looks orange), Jupiter shows far more detail through amateur telescopes than any other planet.

As for finding it, this is a no-brainer. It's the brightest star in the sky by far, and it's out all night long. After nightfall, look for it in the southeast. Around midnight it's in the south. The brightest star: What could be easier?

So put aside any astro-insecurity. Don't say or think, "I wonder if that's Jupiter." If it's far brighter than the other stars, and kind of lowish, be confident: By Jove, you've got it!