We all feel that we are standing still on Earth. We do not feel any movement in our surrounding areas. But if we see at the sky, we can find evidence that we are moving.
Some of the earliest astronomers proposed that Earth is at the center of everything and Sun rotated around us which caused sun rise and sun set - the same for movement of moon as well as planets. This theory is not correct because some times a planet would back up in the sky before resuming its forward direction.. We know that this motion called retrograde motion - happens when Earth is "catching up" with another planet in its orbit. If we take example Mars orbits farther from sun than Earth. At one point in respective orbits of Earth and Mars, we catch up to the Mars and pass it by. As we pass it by, the planet moves backwards in the sky. Then it moves forward again as we have passed.
We know that it takes 365 days for Earth to orbit around Sun. If we look at a close-up star in summer and look at it again in winter, its position in the sky changes because we are at a different point in the orbit. We see the star from different vantage points. With simple calculations, using parallax, we can figure out the distance to the star. Now let us see how fast are we moving..
The spin of Earth is constant but the actual speed depends on what latitude you are located. The circumference of Earth is roughly 40,070 kilometers ( around the equator ). if we estimate that a day is 24 hours long, we get a speed of Earth at Equator as 1.670 Kms per hour. This is the fastest speed because we will not be moving at this speed at other latitudes.
If we move half way up the globe to 45 degrees in latitude ( either north or south ), we can calculate the speed by using the cosine of the latitude. The cosine of 45 degrees is 0.707, the spin speed at 45 degrees latitude is roughly 0.707 X 1.67 = 1.18 Kms per hour. This speed decreases as we move either towards north or south poles. When you reach north or south poles, the speed is very very slow. - It takes entire day to spin in place.
The space agencies try to take advantage of the Earth's spin. If they want to send humans to International Space Station, the preferred location to do so is close to Equator. This is the reason space shuttles are launched from Florida. By doing so and launching in the same direction of Earth's spin, the rockets get a speed boost to help them fly into space. Now let us see how fast are we orbiting the Sun?
The earth takes about 365 days to orbit the Sun and the orbit is an Ellipse. To make the maths simpler, let us assume that it is a circle..So the orbit of Earth is the circumference of a circle. The distance of Earth from sun is 14,95,97,870 Kilometers, this is called as Angstrom Unit. The circumference of Earth is equal to 2 x π x r, so in one year, Earth travels about 940 million kilometers. We know that the speed is equal to distance travelled by the time taken, Earth's speed in our orbit around Sun is calculated by dividing 940 million kilometers by 365.25 days and dividing that results by 24 gives us the speed in Kilometers per hour... Earth travels about 2.6 million kilometers in a day or 1,07,226 Kms per hour ( 29.785 Kms per second)..
Our Galaxy also moves in space relative to other galaxies. In 4 billion years, our galaxy would collide with its nearest neighbour, the Andromeda Galaxy. The two are rushing towards each other at about 112 Kms per second. So everything in the universe is in motion.
Some of the earliest astronomers proposed that Earth is at the center of everything and Sun rotated around us which caused sun rise and sun set - the same for movement of moon as well as planets. This theory is not correct because some times a planet would back up in the sky before resuming its forward direction.. We know that this motion called retrograde motion - happens when Earth is "catching up" with another planet in its orbit. If we take example Mars orbits farther from sun than Earth. At one point in respective orbits of Earth and Mars, we catch up to the Mars and pass it by. As we pass it by, the planet moves backwards in the sky. Then it moves forward again as we have passed.
We know that it takes 365 days for Earth to orbit around Sun. If we look at a close-up star in summer and look at it again in winter, its position in the sky changes because we are at a different point in the orbit. We see the star from different vantage points. With simple calculations, using parallax, we can figure out the distance to the star. Now let us see how fast are we moving..
How fast is the Earth spinning?
The spin of Earth is constant but the actual speed depends on what latitude you are located. The circumference of Earth is roughly 40,070 kilometers ( around the equator ). if we estimate that a day is 24 hours long, we get a speed of Earth at Equator as 1.670 Kms per hour. This is the fastest speed because we will not be moving at this speed at other latitudes.If we move half way up the globe to 45 degrees in latitude ( either north or south ), we can calculate the speed by using the cosine of the latitude. The cosine of 45 degrees is 0.707, the spin speed at 45 degrees latitude is roughly 0.707 X 1.67 = 1.18 Kms per hour. This speed decreases as we move either towards north or south poles. When you reach north or south poles, the speed is very very slow. - It takes entire day to spin in place.
The space agencies try to take advantage of the Earth's spin. If they want to send humans to International Space Station, the preferred location to do so is close to Equator. This is the reason space shuttles are launched from Florida. By doing so and launching in the same direction of Earth's spin, the rockets get a speed boost to help them fly into space. Now let us see how fast are we orbiting the Sun?
How fast is the Earth spinning?
The spin of the Earth is not only the motion we have in space. The Earth also rotates around sun at a speed of about 1,07,000 Kms per hour. We can calculate this also with the help of mathematics.The earth takes about 365 days to orbit the Sun and the orbit is an Ellipse. To make the maths simpler, let us assume that it is a circle..So the orbit of Earth is the circumference of a circle. The distance of Earth from sun is 14,95,97,870 Kilometers, this is called as Angstrom Unit. The circumference of Earth is equal to 2 x π x r, so in one year, Earth travels about 940 million kilometers. We know that the speed is equal to distance travelled by the time taken, Earth's speed in our orbit around Sun is calculated by dividing 940 million kilometers by 365.25 days and dividing that results by 24 gives us the speed in Kilometers per hour... Earth travels about 2.6 million kilometers in a day or 1,07,226 Kms per hour ( 29.785 Kms per second)..
The Sun and Galaxies also move.....
Do you know that the Sun has an orbit of its own in the Milky Way Galaxy. The Sun is about 25,000 light years from the center of Milky Way Galaxy. and the Milky Way is thought to be about 1,00,000 light years across. We are thought to be about half way out from the center according to Stanford University. The sun and solar system appear to be moving at 200 Kms per second or an average speed of 8,28,000 Kms per hour. Even at this rapid speed, the solar system takes about 230 million years to travel all the way around Milky Way Galaxy.Our Galaxy also moves in space relative to other galaxies. In 4 billion years, our galaxy would collide with its nearest neighbour, the Andromeda Galaxy. The two are rushing towards each other at about 112 Kms per second. So everything in the universe is in motion.
What happ ens if Earth stops rotating.....
If Earth stops rotating, there is no chance that you will be fly off into space right now. This is because the gravity of our planet is strong compared to its spinning motion. The spinning motion is called as centripetal acceleration. At the strongest point, i.e. equator, the centripetal acceleration only counter acts Gravity by 0.3 percent only. In other words, you will not even notice that earth stopped rotating. But you will weight slightly less at equator than at poles. As per NASA reports, the probability of Earth stopping its rotating is practically zero for the next few billion years, Theoretically, if Earth stops rotating there would be some effects. The atmosphere would still be moving with original speed of Earth rotation. This means everything would be swept off land, including people, buildings and even trees.
what would happen if the process was more gradual? This is a more likely scenario over billions of years because Sun and Moon are tugging on Earth's spin. This would give plenty of time for the humans, animals and trees to get used to the change. By laws of physics, the slowest spinning speed of Earth would be one revolution every 365 days..This situation is called as "Sun Synchronous" and would force one side of our planet to always face the Sun and other side to permanently face away. Our moon is already in Earth-synchronous rotation where one side of moon is always facing us.
There would be other effects if the Earth completely stopped spinning. As per NASA, the magnetic field would disappear because it is thought to be generated due to spin. We would lose out colourful auroras, and the Van Allen radiation belts surrounding our planet would probably disappear too. Then Earth would be naked against the fury of the Sun. Every time the Sun sends a coronal mass ejection towards Earth, it would hit the surface and bathe everything in the radiation.
Another effect : most spots on Earth would have day light for half a year and nights for other half. The surface temperature during the day would change depending on the latitude you are in. The Equator would be hotter than it is now because the Sun rays directly fall on it. There will not be sun rise and sun set at poles. The sun simply would just move up and down in the sky during the year according to the orbit and tilt. .This long term temperature gradient would change the atmosphere wind circulation pattern. The air would move from equator to the poles rather than in wind systems parallel to equator like they are now.
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