How far? How big? Distance and Size in Astronomy

Need help trying to comprehend the vast distances between astronomical objects? Are you seeking to understand the relative sizes of planets, moons, asteroids, and comets? This page provides links to information, illustrations, images, animations, and interactives on Windows to the Universe about distance and size in astronomy.

Last modified April 21, 2006 by Randy Russell.

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Cool It! Game

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Large and Medium-sized Moons of Saturn

Saturn has // Call the moon count function defined in the document head print_moon_count('saturn'); moons. Many of those are tiny chunks of rock or ice only a few kilometers (miles) across. One of Saturn's...more

Medium-sized Moons of Saturn

Saturn has // Call the moon count function defined in the document head print_moon_count('saturn'); moons. Many of those are tiny chunks of rock or ice only a few kilometers (miles) across. One of Saturn's...more

Solar System Formation

Scientists believe that the solar system was formed when a cloud of gas and dust in space was disturbed, maybe by the explosion of a nearby star (called a supernova). This explosion made waves in space...more

The Solar System

The solar system is made up of the Sun, the // Call the planets count function defined in the document head print_planet_count('planets'); planets and // Call the planets count function defined in the...more

Eris - a dwarf planet

Eris is a dwarf planet in our Solar System. Eris was one of the first three objects classified as a dwarf planet, along with Pluto and Ceres. Eris was first spotted in January 2005. Eris is a large sphere...more

What is a planet?

Do you know what a planet is? If so, you are doing better than professional astronomers! Right now astronomers aren't quite sure how to define a planet. Maybe you've heard that some astronomers think Pluto...more

Orionid Meteor Shower

The Orionid meteor shower happens every year in October. Meteor showers are times when you can see many meteors or "shooting stars" in one night. There are several meteor showers each year. Most meteor...more

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