THE EARTH AND MOON WHAT IS A MOON? • Moon- also known as a satellite, a planet-like object that orbits around a planet. • Earth and Mars are the only terrestrial (rocky) planets to have moons. • All of the gas planets (Jupiter, Saturn, Uranus, and Neptune) all have more than one moon. WHERE DID THE MOON COME FROM? • Scientists have found evidence that the moon was once an asteroid that crashed into the Earth when it was being made. • The asteroid eventually pulled itself away from the Earth, but the Earth’s gravitational pull kept it orbit around the Earth. HOW DOES THE MOON MOVE? • It takes about 29.5 days for the moon to make 1 revolution around the Earth. • The moon has a synchronous rotation with the Earth. • Synchronous Rotation- the Earth and moon rotate in the same direction at the same pace. • That’s why we only see one side of the moon at night. We can never see the backside of the moon from Earth. WHY DOES THE MOON HAVE PHASES? • Phase of the Moon- the shape of the illuminated (sunlit) portion of the moon seen on Earth. • The phases of the moon are produced by the alignment of the moon and the sun in the sky. • The light from the sun is reflected on the moon at different angles. WHAT ARE THE MOON’S PHASES? • New Moon- when the sun and moon are on the same side of the Earth. The part of the moon that is getting the sun’s light cannot be seen from Earth. • Full Moon- The moon and sun are on opposite sides of the Earth. The part of the moon that is getting sunlight is seen from the Earth • Crescent- when the moon is less than half illuminated. • Waxing- when the right half of the moon is illuminated. At the beginning of a moon • Quarter- when the moon is half illuminated. cycle. • Gibbous- when the moon is more than half • Waning- when the left half of the moon is illuminated. illuminated. Near the end of a moon cycle. WHY IS THE MOON SO IMPORTANT? • It is believed to be responsible for the Earth’s tilt. • It has major control over the Earth’s tides. HOW IS THE MOON RESPONSIBLE FOR THE EARTH’S TILT? • It is believed that the Earth’s tilt was created as a result of the collision of the moon into the Earth. • The impact was so great that it literally pushed the Earth’s axis. • Without this collision, the Earth may not have its tilt or its seasons. HOW DOES THE MOON AFFECT THE TIDES? • Tides are created because the Earth and moon are attracted to each other. • The moon tries to pull at anything on Earth to bring it closer, but the Earth can hold onto everything except water. • Since the water is always moving, the Earth cannot hold onto it, and the moon is able to pull it. • Each day there are 2 high tides and 2 low tides. WHEN IS HIGH AND LOW TIDE? • High Tide- occur when the moon is directly overhead or overhead on the opposite side of the planet. When the moon has the larges pull on the water. • Low Tide- when the moon is 90° away (either left or right) from the water. • Other Tides • Spring Tide- When the moon is full or new, the gravitational pull of the moon and sun are combined. At these times, high tides are very high and low tides are very low. • Neap Tide- During the moon’s quarter phases the sun and moon work at right angles, causes the pull of the water to cancel each other. The result is a small difference between high and low tides. WHAT CAUSES AN ECLIPSE? • Solar Eclipse- When the moon passes between the Earth and the sun. • Lunar Eclipse- When the Earth passes between the sun and the moon. • Lunar and solar eclipses occur in pairs that are normally 2 weeks apart. • This is because the Earth, sin, and moon must be aligned for an eclipse to occur..