How fast am I moving?

Driving home a couple of nights ago I started wondering how fast am I actually moving. I mean the speedometer said around 25 km/h through bumper to bumper traffic but I guess it wasn’t the whole picture. I got home and just on an impulse, decided to work it out.

These findings are rough estimates but the order of their magnitude seems correct with the information available to us at the present time.

Let’s see if I look at the rotation of the earth, with an average diameter of 12,800 km from the earth’s center, I am moving at around 1,500 km/h at any given time with my latitude here in Bhopal. Then there is the earth moving around the sun. If we take the distance from the earth to the sun at 1 AU (150 million km), my average speed is 107,000 km/h. At this speed the earth is able to complete one revolution around the sun each year. Suddenly I am starting to get a little dizzy.

The sun is also moving in a complex orbit around its neighborhood of stars. During our lifetime this speed is around 72,000 km/h. This speed changes over time with the change in orbit but on a galactic scale it takes hundreds of years for any significant changes to show so this value is good enough for our calculation.

Now we come to the sun moving around the centre of our galaxy, the milky way. We are 30,000 light years away from the core’s center. With an orbit of about 200 million years our speed comes out to be around 800,000 km/h at any given time. And the milky way also moves around in many complex orbits. First it moves around with respect to its own group of local galaxies (like Andromeda) and this speed is around 144,000 km/h.

Next comes the tricky part. There is a some radiation left over from the Big Bang known as the cosmic microwave background. Using Doppler effect to triangulate this radiation we can roughly calculate that our local group of galaxies is moving at 2,200,000 km/h with respect to this cosmic center.

Unfortunately, we can’t just add up the speeds and come up with an answer since some of these speeds are in opposite directions and on different planes of movement. A good estimate after adding and subtracting these speeds yields that the sun is moving at 1,300,000 km/h (or 1.3 million km/h) with respect to the cosmic radiation, our point of reference. That is even when I am just sitting here typing away. Pretty fast.

There are many other speeds involved which I didn’t take into account here. The earth and the moon circle each other around their center of gravity and that adds another speed, though minor, to these calculations. Plus there is supposed to be another group of super clusters of galaxies much like our own called the Great Attractor. This has not yet been proved but the way gravity bends space around its assumed location, we can tell that something massive is there at the edge of our universe, pulling at us in one specific direction.

So I guess my speedometer was a little off and its no wonder I get so woozy all the time. I thought it was just me, but the fact is that the whole universe is out to get me dizzy by whizzing me at 1.5 million km/h (35 times around the earth on the hour, every hour, 24/7) even when I think I am sitting comfortably in my chair minding my own business.

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