2 Earth moves through space in two ways: revolution and rotation.
3 RotationIt takes 24 hours for Earth to rotate one time on its axis. This 24 hour period is also called a day.The earth rotates west to east. This make the sun appear to rise in the east and set in the west.
4 Revolution It takes 365 ¼ days or one year for Earth to revolve around the sun.This is why stars andconstellations appear indifferent placesthroughout the year.The path an object takeswhile it revolves is called its orbit.
5 The constellations seem to change location in the sky throughout the year. What’s really moving?
6 RevolutionBecause revolution is not exactly 365 days, we have to add one day to the calendar every four years. This is known as leap year.1 orbit= 365 ¼ days¼ + ¼ + ¼ + ¼ = 1 added day
7 Gravity and InertiaHow do the Earth, moon, and other planets stay in orbit? gravity and inertia
8 a. Gravity is a force where two objects are attracted to each other. b. Inertia is the resistance of an object to change its state of motion.c. Gravity pulls an object toward another object, but inertia pulls it away.
10 Ticket Out The Door1. Define rotation. 2. Define revolution. 3. Which motion makes the sun appear to rise in the east and set in the west each day? 4. Which motion makes the constellations in the sky appear to move throughout the year? 5. What force keeps the earth from crashing into the sun?
11 Answers: 1. the spin of an object on its axis 2. an object makes one complete circle around another3. rotation4. revolution5. inertia
12 Seasons The Earth is tilted at 23.5 degrees on its axis, and this is why we haveseasons. As EarthRevolves around thesun, different hemisphereswill be receiving more orless direct sunlight basedon whether the pole is tiltedtoward or away from the sun.
13 Seasons Whatever season is occurring in the Northern hemisphere, the opposite seasonwill be occurring in thesouthern hemisphere.An Australian Christmas card
15 SolsticesSolstices are the two days of the year on which the sun reaches its greatest distance north or south of the equator. The days are longer around the summer solstice (around June in the northern hemisphere) and shorter around the winter solstice (around December in the northern hemisphere).
17 EquinoxesThe equinox is either of the two days or periods each year when the sun crosses the equator and day and night are of equal length of twelve hours. During an equinox, neither hemisphere is tilted toward or away from the sun. The spring or vernal equinox happens around March 20-22, and the autumnal or fall equinox occurs around September in the northern hemisphere (and vice-versa in the southern hemisphere).
19 Moon Motiona. It takes about 28 – 29 days for the moon to revolve around Earth.b. It takes about 28 – 29 days for the moon to rotate on its axis.c. Since the revolution and rotation take the same amount of time, we always see the same side of the moon from Earth.
34 Solar Eclipses What is a solar eclipse? A solar eclipse happens when the moon comes between the Earth and sun, blocking the sun’s rays from the Earth. (The Earth is passing through the moon’s shadow. In other words, a shadow is covering the sun.)A solar eclipse can only happen during a new moon.Observe solar eclipses.
35 Solar EclipsesA total eclipse is when the sun is completely darkened. The moon is 400 times smaller than the Sun, but the moon is also 400 times closer to Earth, so from Earth’s point of view, the entire sun is blocked.The moon’s shadow only covers a small area on Earth’s surface; therefore, only a small section of Earth will be able to observe and experience the eclipse.
39 Lunar Eclipses What is a lunar eclipse? A lunar eclipse occurs when the Earth blocks the rays of the sun from the moon. (The moon passes through the Earth’s shadow. In other words, a shadow is covering the moon.)A lunar eclipse can only happen during a full moon.A total eclipse happens when the moon is completely blocked.
44 Why don’t eclipses happen every month? Most of the time the distance of the shadow is too short to reach the earth or the moon.
45 Also…The orbit of the moon is at a 5 degree angle to the orbit of the earth.
46 Can other planets have eclipses? Yes! A picture of Jupiter and its moon Lo taken by Hubble. The black spot is Lo's shadow.
47 Spring TideWhen the Earth, moon, and sun are in a straight line during new and full moons, a spring tide occurs. The tidal range is greatest. (High tide is higher than normal, and low tide is lower than normal. You will see the greatest differences between high and low tides during a spring tide because the sun and moon’s gravity are working together.)
49 Neap TideWhen the Earth, moon, and sun are forming a right angle during the 1st quarter and 3rd quarter moons, a neap tide occurs. The tidal range is lowest. (There isn’t much difference because the high tide is lower than normal and low tide is higher than normal).