Chapter 1 Orbits Earth and the Moon in

Chapter 1 Orbits

Earth and the Moon in Space o. The Earth and the moon create a system together. o. They revolve, or travel in a closed path, around the sun. o. We call Earth’s path an orbit.

Earth and the Moon in Space o. Earth’s orbit is an ellipse.

Earth’s Rotation o. Earth also rotates, or spins on its axis. o. The axis is an imaginary line passing through the center of Earth’s north and south poles.

Earth’s Rotation

The Moon’s Revolution o. The moon revolves around the Earth in an ellipse-shaped orbit because of gravity. o. Remember: The universal law of gravitation: all objects in the universe are attracted to all other objects in the universe.

The Moon’s Rotation o. The moon also rotates along its axis. o. It takes 27. 3 days for the moon to complete one rotation on its axis.

The Moon’s Rotation o. The same side of the moon always faces Earth because it takes as long to orbit the Earth as it does for it to rotate on its axis.

The Moon’s “Light” o. The moon does not give off light; it reflects sunlight from its surface. o. As its position in the sky changes, we see different phases of the moon.

Chapter 1 The Seasons

The Seasons o. We split the year into four seasons: winter, spring, summer, and fall.

The Seasons o. As the Earth orbits the sun, the amount of sunlight shining on each place changes slightly. o. This causes the seasons.

Earth’s Tilt

Earth’s Tilt o. The Earth is tilted at 23. 5 degrees. o. For half the year, the North is pointed more toward the sun, creating longer days with more sunlight. o. During this time, the Southern hemisphere has shorter days with less sunlight.

Earth’s Tilt o. The seasons are opposite on the Northern and Southern hemispheres. o. During the summer, the sunlight shines more directly on the surface of Earth, creating higher temps.

Earth’s Tilt o. During the winter, the sun hits Earth’s surface at an angle, creating less heat.

The Length of the Day o. In the Northern hemisphere, June 21 st is the longest day and December 21 st is the shortest day. o March 21 st (spring equinox) and September 21 st (autumn equinox) have an equal amount of day and night.

Chapter 1 The Moon’s Features

The Moon’s Surface o. The surface formed from hot, molten rock that turned into a rocky crust when it cooled. o. The moon’s has three main features.

Highlands o. Areas of crust that are higher than the surrounding area; almost like a mountain.

Craters o. The moon has several large and small craters. o. Tycho is 54 miles across.

Maria o“Maria” means “sea” o. Dark, flat areas made of hardened lava – basalt rocks. o. The largest mare is 775 miles across.

Earth and Moon o. Both rocky and dense. o. Both have craters, but the moon has more because meteorites burn as they enter Earth’s atmosphere.

Earth vs. Moon o. The moon has no atmosphere and no liquid water, but frozen water has recently been found. o. No erosion can occur by wind or water.

Chapter 1 The Moon’s Phases

The Phases o. There are 8 phases of the moon that we see throughout its 27. 3 day cycle.

1. The New Moon o. The moon is between the Earth and the sun. o. It cannot be seen due to its position.

2. Waxing Crescent o. The moon is between the Earth and the sun. o. It cannot be seen due to its position.

3. First Quarter o. The moon is one quarter of the way around Earth. o. Looks like a half circle. o. One week into cycle.

4. Waxing Gibbous o. More of the sun’s light is reflecting off of the Earth’s surface.

5. Full Moon o. About two weeks into cycle, we see the entire sunlit part of the moon.

6. Waning Gibbous o. The moon is getting slightly “smaller” (less sun light is reflecting).

7. Last Quarter o. About three weeks into cycle. o. The moon is three-fourths of the way around Earth.

8. Waning Crescent o. The moon’s sunlit part is about to disappear. o. The moon’s cycle is almost complete.

The Moon’s Phases

Chapter 1 Solar and Lunar Eclipses

What is an eclipse? o. Eclipse: when one object passes through the shadow of another. o. Eclipses can occur during a new moon or a full moon when the sun, the Earth, and the moon all line up.

Solar eclipses o. Occurs when Earth passes through a new moon’s shadow. o. The moon completely covers the sun. o. Only the sun’s outer atmosphere is visible.

Solar eclipses

Lunar eclipses o. Occurs when the full moon passes through the Earth’s shadow. o. The Earth blocks the sun’s light. o. Makes the moon appear to be red.

Lunar eclipses

Solar vs. Lunar Solar o. New moon Lunar o. Full moon o. Sun – moon – Earth o. Sun – Earth – moon o. Moon has light around it. o. Moon appears to be red.

Eclipses o. Only 7 eclipses (2 lunar and 5 solar) happen throughout the year. o. Most of these are only partial eclipses.