This is part of a whole solar-system model that spans north Georgia.

Earth ♁

Earth is the third planet from the Sun, after Venus and before Mars. It’s a pretty nice planet to visit. Its diameter is 12,734km. Earth’s orbital distance from the Sun is 149,598,000km or 8.3 light-min, which is defined as 1 astronomical unit, “AU”.

The model of Earth is 20.1cm in diameter, and is 2457m distant from the Georgia Capitol dome in Downtown Atlanta.

Luna

Earth has a moon. We’ve been there. It’s bigger than it should be and it’s made of stuff that is so much like Earth’s that we are pretty sure it came from the collision of a smaller planet with Earth, about 4.5billion years ago, in the early days of the solar system. The Moon orbits Earth at a radius of about 30 times the diameter of Earth, and it gets a few inches farther away every year.

The Moon is tidally locked with Earth. That means it keeps the same face toward Earth all the time. If you lived on the Moon, the Earth would never rise or set; it just hangs in the same part of the sky, forever, spinning on its axis like a slow-moving blue top.

This is also why “dark side of the moon” is a weird expression. There is no side that’s always dark. When we have a new moon, the entire far face of the Moon lit up by sunlight, but we can’t see it.

It’s also a little deceiving to say the Moon orbits “around the Earth”. It’s just as accurate to say that the Moon orbits the Sun at the same orbit as the Earth does. The Moon never moves “retrograde”, or backwards around the Sun, as it goes around the moving Earth. The Moon’s orbit looks more like a flat-sided polygon ⭔, and definitely not like a looping cloverleaf shape ⌘. If the Earth disappeared, the Moon would follow a path that’s slightly more circular. Orbit independence and non-retrograde orbits are true of a lot of moons in our solar system.

Model sites and proposed sites