This cache is close enough to the B-Line Trail that you can pick it up while walking/biking down the trail, but it's also close enough to parking that you could do it as a park-and-grab.
This cache is part of a 1:133,700,000 scale model of the solar system. The dome on the Monroe County Courthouse in downtown Bloomington, Indiana serves as the model of the Sun, and all the planets, dwarf planets, moons, and asteroids are all constructed to the proper size and placed at the proper distance based on that scale. The Earth's diameter is about 12,700-12,760 kilometers, and it ranges from 147 to 152 million kilometers from the sun, so this model is roughly 3.75 inches in diameter and about 0.68 miles from the Courthouse.
The original, super-fancy Earth model with the extra-detailed paint job (pictured above) has gone bye-bye, and its replacement is just a 2D print-out. So if you were hoping to find the original, too late! You can still look at the photos I took of it.
When you find the Earth, take a look back in the direction of the Courthouse. If you could make all the trees and buildings in the way disappear, the dome would appear to be the exact same size from here as the real sun appears in the sky. Isn't that neat? Also, that little scale model of the moon would appear the same size as the moon in the sky does: very slightly smaller than the sun.
Earth is the third planet from the sun and unless you are an astronaut, the planet you are on right now. Earth has one natural satellite, simply called "The Moon". The Moon's radius is about 1,740 km, making its scale model about 1.02 inches in diameter. As the Moon revolves through its 27.3-day orbit, it ranges from about 363 to 406 thousand kilometers from the Earth. On this scale, that's about 9-10 feet. There's a log in Earth, the main stage of the cache, but finding the moon is optional and not required to get your smiley for this cache.
When you find the Moon, take a good look at the sizes of the Earth and the Moon and compare that to the distance between them. For comparison, the satellites you will have used to find this cache are less than an inch from the surface of the Earth. (And GPS satellites are about as far out there as man-made satellites go.) And to think that we sent human beings all the way out to the moon and brought them back safely!
The Earth is just big enough to hold a fair number of small trade items. Sadly, it's not long enough to hold a decent writing implement, so bring your own.
Congratulations to Mouse! for the first-to-find!