Earth, Moon, and Sun

Table of Contents

• Introduction• Our Solar System• Our Sun• Earth• Moon• Solar Eclipse• Lunar Eclipse

For thousands of years, people believed that the Earth was the

center of the universe. Copernicus, Galileo, and other scientists

determined that the Earth and other planets revolved around the Sun.

Introduction

Our Solar System

Our solar system consists of the Sun and all the bodies that orbit it, including eight planets, their moons, asteroids, and comets.

Our Solar System

• Mercury, Venus, Earth, and Mars are the rocky Inner Planets.• The Asteroid Belt is occupied by rocky objects like asteroids and dwarf planets.• Jupiter, Saturn, Uranus, and Neptune are the giant gaseous Outer Planets.• The Kuiper Belt is home to icy objects and some dwarf planets like Pluto.• Click here for animation of the Solar System’s movement..

Comparing Sizes of Planets

Our Sun

Galaxies are huge groups ofmillions or billions or even trillions of stars.

Our Sun is a star located in the spiral- shaped Milky Way galaxy.

Our Sun

Our Sun is a star at the center ofthe Solar System.This gigantic ball ofgas has a nuclear furnace at the center which produces the light and heat that allows life to exist on Earth.

The Sun is about five billion yearsold, and it has enough energy left to shine for another five billion years.

Our Sun

The Sun is much larger than anything else in the Solar System. The Sun’s diameter is about 109 times that of the Earth’s. In other words, about 109 Earths could stretch across the middle of the Sun.

Over 1 million Earths could fit inside the Sun.

Source: http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970518a.html

The Earth

• The Earth is the third planet from the Sun.

• It has one natural satellite, the Moon.

• Click here for animation comparing Earth to the Moon, Jupiter, and the Sun.

Rotation• The Earth rotates around

its axis once a day (approximately 24 hours.)

• The part of Earth that is facing the sun is in light (day), and the part that is facing away from the sun is in dark (night.)

• Click here for animation.NOTE: This animation requires Adobe

Shockwave.

NIGHTFALL IN USA

The biggest concentration of lights (from top to bottom) are the cities of Boston, New York, Philadelphia and Washington.

MiamiHouston

Dallas

Chicago

Still daylight in California.

Puerto Rico

Revolution

• The Earth revolves around the Sun once a year.

• Click here for animations of rotation and revolution.

Moon

The Moon is Earth’s only naturalsatellite. Most scientists believethat the moon was formed whena large piece of rock about the size of Mars crashed into Earth and blasted a huge amount of rockinto space. Over a long period oftime, these rocks condensedtogether to form the Moon.

The Moon

• The moon does not make any light of its own. It shines by reflecting sunlight.

• Sometimes the moon is lit by earthshine, which is sunlight reflected off Earth.

• The moon takes about 28 days,one lunar month, to orbit the Earth.

• It also takes about 28 days to revolve around its axis.

Moon lit by Earthshine

Moon lit by reflected sunlight

The Moon

• As the Moon revolves around the Earth, its appearance seems to change. This is due to the way sunlight reflects off the moon’s surface, which varies depending on the position of the Sun and Moon.

Click here for the current Moon phase.

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Solar EclipseOur Solar System has a

remarkable coincidence. The Sun’s diameter is roughly 400 times larger than the Moon’s, but the Sun is about 400 times farther away than the Moon is. So both objects appear to be about the same size when viewed from Earth.

Solar Eclipse

A solar eclipse occurs when the Moon gets between the Sun and the Earth. Because they are about the same size, the Moon blocks out the Sun’s light. This can only happen during a new moon phase,

Click Here for Solar Eclipse video from NASA

Solar Eclipse

Lunar Eclipse

• A lunar eclipse occurs when Earth gets between the Sun and the Moon during a full moon phase.

• The shadow of the Earth makes the appearance of the Moon seem reddish.

Lunar Eclipse

Click Lunar Eclipse , then “Eclipse Preview” to view eclipse video for February, 2008