The Earth   - Next Planet - Back to Planet Walk
    Earth is the third planet from the Sun, 93,000,000 miles away, and the fifth largest in the solar system, 8000 miles in diameter.

    It was not until Copernicus (the sixteenth century) that it was understood that the Earth is just another planet and not the center of the universe (or even the center of our solar system). At this distance it takes light going at 186,000 miles per second, as fast as possible in this universe, 8.3 minutes to reach the Earth. On this model's scale, to travel at the speed of light you would need to take a 1 inch step every second.

    The correctness of this scale model can now be checked. The apparent size of the Sun on its marker sign 43ft away, is now the same as that of the real Sun, half the width of your little finger held at arm's length. If both the size of an object and its distance have been scaled down by the same factor, then the angle it subtends stays the same.

    The Earth is the first planet we come to that has a moon. The Earth's Moon is the fifth largest moon in the whole solar system, 2147 mi. in diameter or 1/4 the size of the Earth, and is bigger than the planet Pluto. The Moon is the second brightest object in the sky after the Sun. As the Moon orbits around the Earth once per month, the angle between the Earth, the Moon and the Sun changes and we see this as the cycle of the Moon's phases. The Moon doesn't produce it's own light, but it looks bright because it reflects light from the Sun.

    These pictures of the Earth and the Moon are about 100 times larger than the scale of the Planet Walk. Both pictures are courtesy of NASA
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