Did you know you can walk from the Sun to Pluto in about 15 minutes?
By going on the Sagan Planet Walk, sponsored by Ithaca’s Sciencenter, a walk through the solar system is as simple as a quick stroll through the Commons. Along the trail there are stations set up to represent the planets. Each station features a representation of the celestial body at an exact 1 to 5-billion scale. The exhibit puts the massiveness of the cosmos into perspective, scaling the planets down to a few millimeters and the distances between them to nearly a mile.
Until this year, the walk concluded with the Pluto station located at the Sciencenter but as of Sept. 28, the exhibition now ends at a station that features the sun’s closest neighboring star Alpha Centauri, some 5,000 miles away in Hawaii. This addition makes the Sagan Planet Walk the longest exhibit in the world.
History of the Walk
The Sagan Planet Walk, named in memory of late Cornell professor and world-renowned astronomer Carl Sagan, was started in 1997 to educate the public about the solar system. In 1995, the exhibit was first designed at the Sciencenter as an attempt to portray the immensity of the solar system within Ithaca’s boundaries. This goal was achieved by scaling down the distance from the sun to Pluto by 5-billion times into a 1200-meter walk.
Monoliths symbolizing each planet are scattered between the Commons and the Sciencenter at distances representative of the space between the actual planets. Each stone is decorated with the planet’s astronomical symbol. The size of the planet is shown in relation to the sun through a small glass window on the stone. Each station also has several photos from NASA along with facts about the planet.
In 2006, the Sciencenter added a free online audio tour of the walk led by Cornell alumnus Bill Nye, the Science Guy.
On Sept. 28, the Alpha Centauri station, representing the sun's closest star, was officially added to the Sagan Planet Walk exhibition. The monolith representing Alpha Centauri is located at the ‘Imiloa Astronomy Center at the University of Hawaii.
Over the past two years, the Sciencenter has worked with NASA, Cornell University, and the University of Hawaii to create and fund this project. A large sculpture made of volcanic stone represents the star, and several plaques surrounding the area describe the star’s significance. These same signs have been duplicated in the Sciencenter.
Pace the Space
To commemorate the extension, the public participated in a Hawaiian-themed walk on September 29. Several families with children attended; most of them dressed in Hawaiian print shirts and leis. Greg Sloan, senior research associate, astronomy, led the walk. Sloan provided general information and some trivia about each planet along the way.
The walk started at the sun station in the Ithaca Commons, and then continued outward toward the planets and asteroid belt. The asteroid belt station features a 40-kilogram, touchable meteorite, which was added in 2009.
At the Jupiter station, Sloan said that if the planet had 70 times more mass, it could be considered a star due to the intense heat in its core. Arthur Samplaski from the Cornell Astronomical Society said that by December, Jupiter and its moons will be visible from the observatory, which is free to the public every clear Friday night.
Sloan was joined by Peter Thomas, another senior research associate in the astronomy department, who is heavily involved in the Cassini mission. This project is focused on a robotic spacecraft that was sent to examine Saturn in 2004, and will continue until 2017. The mission has provided a great deal of information about the dynamics of Saturn’s rings and moons.
Sloan said that Cassini has shown that the function of Saturn’s shepherd moons, which are the moons that orbit near a planet’s rings, is to “keep the edges of the rings nice and sharp.” Thomas further explained that Titan, one of Saturn’s moons, is the only one in the solar system with a noticeable atmosphere and lakes on its surface.
At the Uranus station, Sloan explained that Cornell astronomers actually discovered the rings around the planet: they noticed that a star blinked five times on both sides of the planet in a perfectly symmetric manner, implying that Uranus had rings.
The last station in the Ithaca portion of the exhibit was for Pluto. Though it is no longer considered a planet, Pluto is labeled a “dwarf planet,” like Ceres, which is located in the inner solar system.
“The main reason Pluto is still there is because it is locked in resonance with Neptune; their orbits overlap, like a wonderful dance,” said Sloan.
The walk ends with Alpha Centauri, which can be classified as a “triple star” because it is a cluster of two Sun-like stars and a red dwarf star. In the back of the Sciencenter, there is a large photo of the new station in Hawaii as well as several panels describing Alpha Centauri.
Correction: A previous version of this story incorrectly stated the society to which Arthur Samplaski belongs. It is the Cornell Astronomical Society, not the Cornell Astrological society.