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Sagan Planet Walk

The Sagan Planet Walk is a walking scale model of the solar system, extending 1.2 km from the center of The Commons in downtown Ithaca, NY, to the Sciencenter, a hands-on museum featuring over 250 exhibits.

The exhibition was created in memory of Ithaca resident and Cornell Professor Carl Sagan by the Sciencenter in 1997. Professor Sagan had been a founding member of the museum's advisory board and was instrumental in developing the institution's educational philosophy.

Update June 6, 2013: The City of Ithaca has begun an estimated 1.5 year reconstruction of the downtown Ithaca Commons. As a result, the permanent Sagan Planet Walk monuments for the Sun, Mercury, Venus, Earth and Mars have been removed and temporary stations in the form of painted panels along the construction wall are up. You can still walk the entire Sagan Planet Walk, originating at the center of the Ithaca Commons (at American Crafts), and follow the usual pace towards M&T Bank. Around the corner on Seneca St is the Asteroid Belt and the rest of the Sagan Planet Walk can be followed to the Sciencenter.

Passports may still be purchased at all participating locations; the Sun and inner planet stamps can be obtained at M&T Bank and 15 Steps. While at the Sciencenter, be sure to check out the replica of the Alpha Centauri station (located in Hawaii).

Update May 14, 2014: The Ithaca Commons Construction is to be complete November 2014.

We will continue to update this page as we learn more about the developments of the construction.

Free Audio Tour

Learn more about the Solar System and the planets as you explore the Sagan Planet Walk. The FREE tour is narrated by Bill Nye the Science Guy. Listen to the tour by phone at 703.637.6237. Download from iTunes or our Sagan Planet Walk Podcast Page.

Passport to the Solar System

Purchase a "Passport to the Solar System" for $4 and take your fully stamped passport to the Sciencenter to receive one free admission.

You can also download the "Passport to the Solar System" for free below. Please note that the downloadable passports do not qualify for free admission to the Sciencenter.


Archive: Dedication and Press Releases

History, Biography & Addendums

Project Design Measurements

Scale factor = 5,000,000,000:1

Orbit Radius


Object Diameter

Scaled Orbit

Radius (meters)

Scaled Object Diameter


Sun 0 1,392,000 0 278
Mercury 58,000,000 4,980 12 1.0
Venus 108,000,000 12,360 22 2.5
Earth 150,000,000 12,742 30 2.5
Mars 228,000,000 6,760 46 1.4
Jupiter 778,000,000 142,600 156 28.5
Saturn 1,430,000,000 120,600 286 24.1
Uranus 2,870,000,000 47,000 574 9.4
Neptune 4,490,000,000 44,600 898 8.9
Pluto 5,900,000,000 2,274 1,180 0.4
Doc Kinne created this portion of the web site in 2001 as part of his Graduate Projects in Astronomy at the Swinburne Center of Astrophysics and Supercomputing Melbourne, Australia.