What is a Tide? http://aspire.cosmic-ray.org/Labs/Tides/tides_simulator.html • A tide is the rise and fall of the surface level of a body of water due to the Moon’s and the Sun’s gravitational pull.
Gravitational Pull? • Earth and the other planets are kept in orbit around the Sun by the Sun’s gravity. The more massive an object is, the greater the force of gravity that pulls on another object. • The Moon’s gravity distorts the sea level so that the sea is slightly higher on the side of Earth closer to the Moon and also on the side of Earth further from the moon.
High Tide • When a location on Earth is located so that it faces the moon or is opposite the moon, the bulge of water is at it’s highest point, or HIGH TIDE.
Low Tide • Between these two areas are low areas because water has been pulled away to form the bulge. These areas experience LOW TIDE.
What About The Sun? • The sun also has an influence on the tides. Even though the sun is further away, it has much more mass than the Moon. • If the Sun and Moon are pulling in the same direction on Earth, when the three bodies are in line, the tides are stronger. This is called a SPRING TIDE.
What About The Sun? • If the sun is pulling on Earth at a right angle from the moon, the tides are weaker. This is called a NEAP TIDE.
Stop and think • If the tide is high where you are, is the tide high or low on the side of Earth directly opposite you? • If the Earth did not turn, how would the pattern of tides be affected?
What is an Eclipse? • An eclipse is the blocking of light from one object in space by another object in space. • Solar • Lunar http://www.youtube.com/watch?v=tIE1MTGz4eI
Lunar Eclipse • When the Moon passes through Earth’s shadow so that some or all of the Moon can only be seen by reflected light from Earth. Lunar eclipse happen more often than solar. http://micro.magnet.fsu.edu/primer/java/scienceopticsu/lunar/
Draw this diagram of a lunar eclipse!They typically happen About 2-3 per year
Solar Eclipse • A solar eclipse is when the Moon passes between the Sun and the Earth, so that light from the Sun is partially or totally blocked. http://www.youtube.com/watch?v=_201ttTSG30
Total Eclipse • COMPLETE BLOCKING OF LIGHT! • Total eclipses rare – only once every 360 years!
Partial Eclipse • Blocking of only a PORTION OF LIGHT. http://highered.mcgraw-hill.com/sites/0072482621/student_view0/interactives.html
In Your Notebooks: • Please answer the following questions in complete sentences and be prepared to discuss: • What impact does the Moon have on Earth’s oceans? • What impact does the Sun have on Earth’s oceans? • What causes a high tide? • What causes a low tide? • What is a solar eclipse? Draw and label a solar eclipse in your notebook. • What is a lunar eclipse? Draw and label a lunar eclipse in your notebook.