Moons

What is a moon? Funny thing is, scientists haven't decided yet! You might recall the IAU or International Astronomical Union, changed the definition of what a planet is recently recently and some scientists think the definition for Moon is next. For now a moon is simply defined as an object (not manufactured), in orbit around another object.

Image at right: Earth's moon, Calisto, Rhea, Mimas, Io (Original images courtesy of NASA.)

Where do Moons come from? Some moons are caused by collisions with their planet that break off a piece of the crust. Other moons may have been created while their planet was forming or could have been passing objects, captured by their planet's gravity.

Our Moon
The Moon is the closest neighbor we have in the sky, and is the one we know the most about. The Moon plays an important role in our lives every day from the tides its gravitational pull creates in our oceans to the organization of our calendars and how we tell time. Image at right: Our Moon (courtesy of NASA).
Learn more on the Our Moon page

Other Moons
Although the Earth's Moon is most well known of all moons, there are many others worth studying. Some planets have many moons, while others have none at all. Even dwarf planets Pluto and Eris have moons. Image at right: Europa, Ganymede, Io, Callisto (Original image courtesy of NASA.)
Learn more on the Other Moons page

Around the Adler

Our Doane Observatory is open every Third Thursday for Adler After Dark.

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Did you know?: Over its flight career, space shuttle Endeavour flew 122853151 miles and spent 299 days in space.

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