IAN pages 20 and 21

ECLIPSES AND TIDES

I. Eclipses occur when one objects shadow blocks light from hitting another object. The shadow caused by the first object has two parts A. The Umbra- If the second object passes through this

part of the shadow, a total eclipse will occur.B. The Penumbra- If the second object passes

completely into this part of the shadow, a partial eclipse will occur.

II. Lunar Eclipse- A lunar eclipse occurs when the earth’s shadow blocks the sun light from hitting the moon. This can only occur during a full moon phase. Lunar eclipses can be total or partial depending on how much of the moon is blocked by earth’s shadow.

III. Solar eclipse- A solar eclipse occurs when the moon blocks sun light from getting to certain parts of the earth. The moon is much smaller than the sun and earth, so the area of earth that experiences a solar eclipse is small. If you are in the umbra of the moons shadow, you will see a total or annular eclipse. If you are in the penumbra, you will see a partial eclipse.

A. Annular Solar eclipse- This eclipse occurs when the moon passes in front of the sun, but is far enough away in its orbit that it only blocks the center of the sun.

B. Partial eclipse- This occurs when only part of the sun is blocked. People living in the area where the penumbra blocks the sun will see this.

C. Total eclipse- This occurs when the sun is completely blocked by the moon. People living in areas where the umbra blocks the sun will see this. The moon must also be the correct distance from earth for this to happen.

IV. Earth’s Tides- Tides on earth are caused by the moon’s and sun’s gravity pulling on it. This gravitational pull causes the oceans water to bulge in the direction of the moon. The moon has more of an affect on tides than the sun, but when the two are lined up, the tides are more extreme. There are two high tides and two low tides each day.