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Introduction:
The Earth is spinning on its axis as it travels around the sun. However, it’s not turning like a perfect top. In order to understand how the rotation of the Earth causes day and night, we need to learn about the tilt of the earth. For more than two centuries, scientists understood that Earth’s axis (the imaginary line running through our planet’s rotational pole) was tilted at an angle of about 23° from vertical. The earth rotates on its axis and revolves around the sun, and both these motions cause a cycle of day and night to occur.
What is Rotation?
Observations of the motion of the stars to make certain predictions about the motion of Earth, scientists have come to know that Earth rotates in a circular path with its axis tilted at 23° from vertical.
Earth’s Revolution around Sun and Rotation of the Earth with its Axis tilted at 23 Degree from vertical. The rotation of the earth takes 24 hours and each day, Earth completes 360° rotation on its axis, hence it needs 24 hours to rotate once. In this continuous motion, Earth’s axis rotates at a constant rate of about 2° per hour. A day isn’t as simple as it may sound, because in addition to rotating on its axis and constantly travelling around the sun, our planet also orbits the sun once in a year and this daily movement explains why different parts of our planet receive different amounts of energy during the year.
What is Revolution?
The revolution of Earth around the Sun is a motion in which earth travels from one point to another at a constant speed. This motion determines the duration and length of each season on our planet. 365 days are required for Earth to complete its journey around the sun. Earth spins on its axis at the same time it revolves around the sun. Earth’s Revolution around Sun and Rotation of the Earth with its Axis tilted at 23 Degree from vertical.
How is Rotation different from Revolution?
Rotation is the spinning motion of earth on its axis. This motion determines the duration and length of night and day on our planet. Revolution is the movement of Earth from one point to another as it travels around the Sun. This motion explains why different parts of our planet receive different amounts of energy during the year.
Effect of motion of Earth on Day:
Because the Sun is much farther from Earth than the stars, it appears to move in an arc across the sky. Imagine a beach ball on a string, swinging back and forth above your head. As you turn, the ball appears to rise above and descend below your line of sight. In exactly the same way, as Earth rotates on its axis every 24 hours, the Sun appears to trace out an arc across the sky. This path is called the ecliptic. It’s very close (but not quite exact) to what we think of as the path of true north. The earth’s rotation is what causes the sun to appear in the sky continuously. As soon as one side of the planet faces the sun, that part experiences daylight even though it is not actually daytime there. The other side of the Earth will be experiencing night time even though it is also not daytime there.
Effect of motion of Earth on Night:
Just as day begins with sunrise, so does night begin with sunset. Both happen because of how quickly time passes for us due to our orbital motion around this star we call our sun.
What is Summer Solstice and Winter Solstice?
The Earth’s axis is not exactly horizontal. It leans a little bit to one side, so that the part of the Earth that faces our sun is a little higher than it would be otherwise. This tilt is called obliquity (from the Latin for “to twist”).
In the summer, the northern part of the Earth is tilted a little farther away from the sun than it is in winter. It takes a few minutes longer for sunlight to reach a person at the North Pole in June than at the South Pole in December, so daylight is not as long and nights are not as short. At Northern Hemisphere’s summer solstice, when that part of Earth is tilted toward the sun, it receives more direct sunlight and stays warmer throughout its days and nights
On 21 December (or 22 December for those who use a different calendar, we have reached the winter solstice. The Earth’s axis has swung so that it is pointing away from our star.
Conclusion:
To conclude, we would like to say that Earth rotates on its axis and revolves around the sun at the same time. The speed of revolution and rotation are different because there is a difference in distance between the earth and Sun. Due to Revolution of the earth, day and night occur during our year. As explained above, during the year there are several changes in our planet because of this motion. Now we understand why it is important to know about these revolutions as it tells us about how planets behave in space.
