Earth is about 3.1 million miles closer to the Sun at perihelion in January than it is at aphelion in July.

It takes approximately half a year (184 days) for Earth to go from perihelion to aphelion. Doing the simple division, Earth is therefore moving at an average speed of about 700 miles per hour towards (aphelion to perihelion) or away from (perihelion to aphelion) the Sun while zipping around in our orbit at 67,000 miles per hour around the Sun.

Richard already answered the general question about Earth’s average speed around the Sun, but I wanted to address the question of changes in Earth’s speed around the Sun arising from our slightly elliptical orbit.

A few days ago Earth passed its perihelion, the point in its orbit at which the Earth-Sun distance is at a minimum (91 million miles).

Per Kepler’s 2nd law of planetary motion regarding elliptical orbits, that’s also when we’re travelling fastest around the Sun. At aphelion, our greatest distance from the Sun (95 million miles), our orbit is slowest.

Earth’s orbit around the Sun averages 29.8 kilometers/second, but what’s our speed around the Sun at perihelion (closest to the Sun) and aphelion (most distant from the Sun)?

This would require some number-crunching, and planetarium staff members Duke Johnson and Robert Bigelow produced the numbers for this question. At perihelion, we’re orbiting the Sun at the rate of 30.3 km/sec, and at aphelion we’ve slowed to 29.3 km/sec.

That one kilometer per second speed difference between slowest and fastest works out to a difference in speeds of better than 2,200 miles per hour.

Since we’ve got six months between aphelion and perihelion, the acceleration needed to change our orbital speed by one kilometer per second in that time period is vanishingly small, so you never feel the change in our speed around the Sun.

But, keeping things simple, there is a factor that is worth noting here. Johannes Kepler, a 17th century astronomy and mathematician, taught us some important scientific truths about planetary orbits, now known as Kepler’s Laws of Orbits. The first law states that planets orbit the Sun in ellipses, not perfect circles, with the Sun as one of the two focal points of the ellipse. This means that there is a point when Earth is closest to the Sun (called perihelion) and a point where Earth is farthest from the Sun (called aphelion). Kepler’s second law tells us that as a planet gets closer to the Sun in its orbital path, its orbital speed will increase; and as the distance between the planet and the Sun increases, its orbital speed decreases.

Interestingly enough, at least for those of us living in the northern hemisphere, Earth is closest to Sun in early January (January 2nd, 2010) and farthest from Sun in early July (July 6th, 2010). However, this change in separation distance is not the cause of seasons on Earth.

So, to answer your question, yes, the speed of the Earth in its orbit does change with the seasons/times of year, but change in seasons are not the cause or effect of the change in orbital speed.

Can the police book the earth? Will the speed camera pick up our
solar system speed or our galaxy speed? Hm!

Don’t speed, because we are already speeding! Ha, ha.
Yet our rocket space ships can just manage 50000km/hr or more by gravitational
pull from planets. Aren’t we modern.

Will we eventually contract back though because of gravity sucking us back?
because of mass attraction. Sooner or later F=ma must reduce to nill and
then we will go to f=mgh. Just a thought! Just a thought!

Amazing universe isn’t it! Just another thought, no wonder we should worry about asteroids when we are speeding at over 105 000km/hr.

they are not going to hit us! Its just that we are going so bloody fast.