At what speed?

Question

AT what speed does the earth travel round the sun?

Answer 1

In scientific terms it's about 30 km/s, that is about 10^(- 4) of the speed of light, which gives it some context.

Because of this, there is an angular ABERRATION (apparent shift in the positions of stars in the sky) with a MAXIMUM ampitude of 10^(- 4) rad ≈ 20.5 arc sec.

Throughout the course of a complete year, EVERY star in the sky makes a little ellipse of apparent directions (as measured from Earth) with angular semi-major axis of that same 20.5 arc sec. For every star there are two times a year where the Earth's orbital motion is PERPENDICULAR to the star's line of sight --- think of the Earth's own projected orbit as seen from any star. That is when the light from a given star has its greatest aberrational displacement from its mean direction.

Of course, the aberrational ellipse COULD be a perfect circle (for a star exactly at one or other pole of its orbit), or a STRAIGHT LINE (a degenerate ellipse) because the star is in the plane of Earth's orbit.

It was because of already KNOWING the speed of the Earth in its orbit that the English Astronomer Royal Bradley was able to take his DISCOVERY and MEASUREMENT of the aberrational angle and obtain a refined value for the speed of light --- the second astronomical measurement of it, in fact. (The first was the Dane Roemer with his observations of ingress and egress times for occultations of Jupiter's Galilean satellites, but his result was off by some 25%.)

So, knowing the speed of the Earth in its orbit played a significant historical role in improving the then current value for the speed of light.

Live long and prosper.

Answer 2

1) From the web: 18.55 miles per second
http://members.aol.com/nlpjp/speed.htm

2) A simple estimate

a) Assume the Earth is in a circular orbit, of radius A, around the Sun which is assumed to be fixed in space.
A = 1.5E08 KM

b) Let n be the angular velocity of the Earth around the Sun
n = 2 * PI radians per year

c) Let S be the speed of the Earth
S = n * A = 2 * PI * 1.5E08 = 9.4247E08 KM/year
= 9.4247E08 * ( 1 / 365) * (1 / 24) * (1 / 3600) = 0.29885 km / sec
= ( 0.29885 km/sec ) * ( 0.62 miles/km ) = 18.53 miles/sec

Answer 3

Our orbit around the sun is an ellipse, not a circle, so Earth's speed around the sun varies slightly. Average speed is 67,108 mph.

Answer 4

And you can add in the speed of the sun and its solar system as it orbits our galactic centre at 200km/sec. You can work this out knowing the mass of our galaxy and the radius of our sun from the centre- approx 20million light yrs (using V^2/R=G*M/R^2 where M=mass of galaxy= 5x42Kg adjusted for proportion of mass within that radius). So it takes the solar system about 250million years to orbit the galaxy.
Top Tip: Another Permian Era could be due with 5Deg global warming and extinction of 95% of species.

Answer 5

The Earth is 93 million miles from the Sun and so the circumference of its orbit is 2 pi times that, i.e. 584 million miles. It travels this distance in one year, which is 31.6 million seconds (figure it out: 365.25 days x 24 hours x 60 minutes x 60 sec). So the Earth is moving at 584/31.6 = 18.5 miles per second. Or, in metric, 30 km/sec.

Answer 6

At what time? It varies over the year, and a tiny bit from year to year.

On April 7, 00:00 UT:
tangential speed = 107,096 kilometers per hour
... ( = 29.75 km/sec = 66,546 mph )
radial speed = +1,816 kph (away from Sun)
... ( = +1,129 mph )

Six months later, the values are 29.30 km / sec (66,658 mph) and -0.490 km/sec (= -1,097 mph) (toward the Sun).

Answer 7

fast

Answer 8

66,000 MPH, approximately.

Answer 9

30 km/s or 108000 km/h.

Answer 10

faster then forest gump can run