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The Earth in Space Vocabulary | Organizer | Experiments | Brainpop | Student Work Adobe Reader is needed to view the calendars. If necessary
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Focus question: How does Earth move in space? What happens when Earth moves? Earth in Space When we think about it, Earth is an amazing planet. This huge mass of rock and water hangs suspended in space, and moves in very predictable ways (meaning ways in which humans can tell what will happen next). Earth's movement in space causes different things to happen. This unique movement causes day and night, different time zones, and seasons. Essentially, these phenomena influence the passage of hours, minutes, seconds, along with months and years. Earth's Rotation It takes Earth 24 hours (one day) to make one complete rotation. The Earth rotates, or spins, like a top on its axis. The axis is an imaginary line that passes through Earth's center vertically. Earth has two poles, one north, and the other south. While the Earth rotates, half of the planet faces the Sun. This half receives sunlight. During this time, the areas of the world, which face the Sun, have daytime. Something different happens on the opposite side of Earth. While one side is in sunlight, the opposite side is in darkness; it does not receive sunlight. Therefore, it is nighttime in the parts of the world that are not facing the Sun. You may think the clock controls time, but really it is the Earths' rotation that tells us when to wake up and when to go to sleep. The clock just makes it easier for us to keep track of time. While Earth rotates, different parts of the world receive changing amounts of sunlight. This causes us to have time zones, which are areas of the world that have their own time. We live in the Eastern Standard Time Zone. When the Sun is directly overhead, it is noontime (12:00PM). The time zone to the right of us is one hour earlier, so it would be 1:00 PM for people in the Atlantic Standard Time Zone. The time zone to the left of us is one hour earlier, so it would be 11:00 AM in the Central Time Zone. The United States has 8 different time zones, and the entire world has 24 time zones, one for each hour of the day. One way of remembering this is to think: west is less, east increase. Earth rotates from west to east (think of this: "WE rotate" which stands for west to east). Since the Earth rotates in this direction, the opposite happens. The Sun appears to rise in the east and sets in the west. Earth's Revolution While Earth rotates, it also revolves, which means it moves around another object. The object Earth revolves around is the Sun. This trip around the Sun takes Earth 365 1/4 days to complete. The Earth's movement around the Sun makes something amazing happen- it causes us to have seasons. We have seasons for three reasons: 1. Earth is tilted on an axis (23.5 degrees) 2. Direct and indirect sunrays 3. Earth travels around the Sun in an elliptical path Earth is tilted on a 23.5 degree axis. When it revolves around the Sun, this tilt causes different parts of the Earth to lean toward or away from the Sun during different points in the year. The part of the Earth that is tilted toward the Sun is hit with direct sunrays, which are sunrays that are very strong because they hit the Earth directly. The people who live in those areas experience Summer. The opposite half of Earth which is titled away from the Sun has indirect sunrays, or sunrays that hit Earth on an angle. Indirect rays are not as strong, so that part of Earth has Winter. These seasons are referred to as solstices. The winter solstice begins on December 21st, and the summer solstice begins on June 21st. As the Earth continues its journey, there are times when neither the
northern nor southern hemisphere is leaning toward the Sun. The result is
that Earth receives similar amounts of direct sun. We call these seasons
Fall or Spring, also referred to as equinoxes. The vernal equinox (spring) begins on March 21,
and the autumnal equinox (fall) begins on September 21st. The Earth is closest to the Sun on January 3rd. You may ask yourself why, then, is it so cold in the Northern Hemisphere if we are closest to the Sun. The reason is because where we live, the Earth is tilted AWAY from the Sun, therefore the sun rays are indirect. Think about a lamp. If you stand directly below a lamp, you will feel the direct heat from the lamp. If you stand next to it, you will feel indirect heat. Also, Earth is farthest away from the Sun on June 3rd. Why is it warm in the Northern Hemisphere? You guessed it! Our part of Earth is tilted toward the Sun. Conclusion As you can see, since the Earth rotates and revolves, we many different phenomena have day and night, time zones, and changes in seasons. If for some reason it stopped moving in this way, life on Earth would change dramatically. While you go on to learn about more of these phenomena, keep this thought in mind!
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