"What's everybody's favorite planet?" asked Bill Nye to a group of about 50 people gathered on the Ithaca Commons March 7 for a guided tour of the Sagan Planet Walk. "Well for me, it's Earth all the way," he answered. "I grew up on Earth, and Earth is my home planet. If it's Earth versus Saturn in a hockey game, it's all Earth for me."

Bill Nye, a 1977 graduate of Cornell's Sibley School of Mechanical and Aerospace Engineering, was on campus last week for his final visit as a Frank H.T. Rhodes Class of '56 University Professor. And he chose to make his grand exit by exploring the sun and its nine planets.

As Nye led his retinue through Ithaca's model solar system -- with each body marked on a plinth at its relative distance from the sun on the Ithaca Commons out to Pluto at the Ithaca Sciencenter, 1,200 meters (.75 miles) away -- he explained through his megaphone the unique features of each.

The surface of Venus is so hot, he said, that "lead would melt, aluminum would almost melt, and we would be fried people."

At Earth, which he described to the group as that "pale blue dot," Nye quoted Carl Sagan, the David Duncan Professor of Astronomy and Space Sciences at Cornell who died in 1996 and for whom the planet walk is named, as saying that every supreme commander, every superstar, every supermodel, every couple in love, every little kid, every grown up, everyone ever has lived his or her entire life on that tiny blue dot.

The vast distances between the planets became most evident once Nye's fellow travelers left the close proximities of the terrestrial planets on the Commons and proceeded out into the realm of gas giants.

Jupiter, which sits at the corner of the DeWitt Mall, has a gravity field that has "helped us live as well as we do on Earth," said Nye. This is because Jupiter's gravity "sucks in meteors and asteroids" from the asteroid belt that get pulled in before they have a chance to hit Earth. "So far, that's been really good for us," continued Nye. "I haven't contacted anyone at Jupiter to thank them, but I'm sure they'd be delighted."

Nye also said that Jupiter's great red spot is a "hurricane" that is very stable. "And so, when you study a storm on Jupiter, maybe you can discover something about the next Katrina or Rita."

The remaining planets were even more distant from one another as the group walked to the icy edge of the Kuiper Belt. By the time Nye's group reached the "ice dwarf" Pluto, the Ithaca "astronauts" had walked almost one mile on Earth but more than 5 billion miles from the center of the solar system to its icy outer limits. Had the crowd wanted to continue on to the next closest star system, Alpha Centauri, over 25 trillion miles away on the same scale, they would have had to go all the way to Hawaii.

The event was hosted by Cornell and the Ithaca Sciencenter.

Graduate student Sandra Holley is a writer intern at the Cornell News Service.