Earth's orbit and relative speed/time

In summary, the Earth's orbital speed is affected by the Sun's gravitational pull, but the time dilation effect is very small. The average velocity of the Earth around the sun is 29.7 km/sec, which is a small fraction of the speed of light. The velocity of the sun around the center of the Milky Way and the velocity of the Local Group of galaxies also play a role in time dilation. However, time dilation is relative and can be seen differently by different observers. The combined effect of the Earth's orbital speed and the Sun's gravity is on the order of microseconds.
  • #1
jezzabeanz
1
0
Hi,

I am curious whether that when the Earth is in its closest position to the Sun, the Suns gravitational pull has a direct effect on the Earths orbital speed. Since the speed of an object has an effect on time. Would the increase in speed affect time in general. Of course the time is relative to us.

I apologise I am struggling to word this.
 
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  • #2
Relativistic effects generally require relativistic velocities. The average velocity of the Earth around the sun is 29.7 km.sec, which is 10-4 of the speed of light. So the time dilation of Earth time as measured by an observer stationary with respect to the sun would be about a part in 10-8. The velocity varies from 29.3 at aphelion to 30.3 at perihelion, about one percent.

On the other hand, the velocity of the sun around the center of the Milky Way is one order of magnitude greater, 220 km/sec. And the velocity of the Local Group of galaxies with respect to the cosmic microwave background is greater still, 600 km/sec.

Remember that time dilation is relative, not absolute, it's in the eye of the observer. You could still argue that being at rest in the CMB is more fundamental than being at rest on the Earth, and moreover the Earth is accelerating.
 
  • #3
There are two effects, a special relativistic effect due to the Earth moving slightly faster at perihelion, plus a general relativistic effect due to perihelion being slightly deeper in the Sun's gravity well. The combined effect is very small, on the order of microseconds.

See http://adsabs.harvard.edu/full/1998A&A...336..381S.
 

FAQ: Earth's orbit and relative speed/time

1. What is Earth's orbit?

Earth's orbit refers to the path that Earth takes as it revolves around the Sun. It is an elliptical shape, meaning it is slightly oval-shaped, and it takes approximately 365.24 days for Earth to complete one orbit around the Sun.

2. What is Earth's relative speed in its orbit?

Earth's relative speed in its orbit varies depending on its position in the orbit. At its closest point to the Sun, called perihelion, Earth travels at a speed of about 67,000 miles per hour. At its farthest point from the Sun, called aphelion, Earth's speed slows down to about 63,000 miles per hour.

3. How does Earth's orbit affect the length of a year?

Earth's orbit is what determines the length of a year. Since it takes approximately 365.24 days for Earth to complete one orbit around the Sun, that is how long it takes for Earth to make one full revolution and return to its starting point in its orbit.

4. What is the difference between Earth's sidereal and synodic year?

Earth's sidereal year is the time it takes for Earth to make one full orbit around the Sun relative to the fixed stars. It is about 20 minutes longer than the synodic year, which is the time it takes for Earth to make one full orbit relative to the Sun. This difference is due to the fact that Earth is also moving in its orbit around the Sun, so it takes a little longer to return to the same position relative to the stars.

5. How does Earth's tilt affect its orbit and seasons?

Earth's tilt, which is approximately 23.5 degrees, has a significant impact on its orbit and the changing of seasons. As Earth orbits the Sun, its tilt causes the Northern and Southern Hemispheres to receive different amounts of sunlight at different times of the year, leading to the changing of seasons. Earth's tilt also causes the length of daylight hours to vary throughout the year.

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