Chapter 1 Section 2Phases, Eclipses, and Tides

Objective: Students will define phase, eclipse, and tide.

Star Log: #2 What does “phases of the moon” mean?

Phases of the Moon

• The positions of the moon, Earth, and the sun cause the phases of the moon, eclipses, and tides.

• The phase of the moon you see depends on how much of the sunlit side of the moon faces Earth.

Moon Phases

Moon Facts

• The moon does not have it’s own light, it reflects light from the sun.

• The amount of the sunlit side of the moon that you can see determines its phase.

• The moon goes through a whole set of phases about once a month.

Solar and Lunar Eclipses

• Solar Eclipse– A solar eclipse occurs when the moon

passes between the Earth and the sun, blocking the sunlight from reaching the Earth.

• Lunar Eclipse– A lunar eclipse occurs at a full moon when

Earth is directly between the moon and the sun.

Solar and Lunar Eclipses

What is a tide?

• A tide is the rise and fall of water every 12.5 hours.

• The water rises for about 6 hours and then falls for about 6 hours.

What causes the tides?

• The force of the gravity pulls the moon Earth (especially the water on Earth’s surface) toward each other.

• Tides occur mainly because of differences in how much the moon pulls on different parts of the Earth.

Spring and Neap Tides

• Spring Tides– Once a month, at a new moon, the sun,

Earth, and moon are nearly in a line.– The gravity of the sun and moon pull in the

same direction causing a tide with the greatest difference between low and high tide.

• Neap Tides– Twice a month when the Earth and sun are

at right angles to line between the Earth and moon.

– The sun and moon pulling in these directions causes a tide with the least difference between low and high tide.

Class Review

• Why does the moon change its phases as the month progresses?

• Why are a day and a year on the moon the same length?

Homework for Tonight

• Page 45 – Key Terms for Chapter 1 Section 2– Read the Key ideas for Section 2