Does the Earth begin its rotation of the Sun at the same point every time ?

Question

It takes 365-366 days for the earth to complete a full rotation around the sun.

A full circle (rotation), is 360 degrees.

There fore am I correct in saying the earth has a different starting point (from day 1), each time?

( A difference of 5-6 degrees each time)

Answer 1

You are assuming that the Earth revolves 1 degree round the Sun per day. It doesn't, the actual figure is slightly less than 1 degree. It  averages out at about 360/365.25 degrees per day. There is a zero point in the Earth's orbit, however. This is known as the Vernal Equinox, which the earth reaches at about March 21st each year. The number of leap years in the calendar is deliberately arranged to keep this zero point either on or close to this same date for centuries to come.

Answer 2

The earth is very regular in its rotation about its axis and revolution around the sun. Our "day" length is proclaimed by man. The orbital period, however, does not fit perfectly with the number of days we give a year. So, here comes the leap year. Every four years, an extra day is added to our calendar to bring it back into sync with the earth's travel about the sun. First, it was the Julian calendar, then came Augustus to change it again. Then Pope Gregory got his hands on it, so that's what we have today, the Gregorian calendar.

As for your particular question, the earth has the same starting point for each revolution.

Answer 3

You've noticed the thing about the 360 degrees and the ~365 day orbit. And you have realised they are different. Each day, Earth moves just a tad more than 1 degree in its orbit (~365/360, degrees actually).

To be more accurate, let's distinguish between rotation and revolution. The Earth REVOLVES around the sun once a year. Rotation is what Earth does to have days.

But we define a year as the time it takes for a complete revolution. So this doesn't allow for Earth to start a year in any different location than it began.  

Answer 4

The easy answer is no.

Earth's orbit is not the precise, closed loop that most people think it is.  Earth does not retrace the exact same orbit every time around.

The differences are due to other planets (and our Moon, of course).

Our Moon causes quite a zig-zag in our orbit: over a thousand kilometres one way and the other.  When the Moon is between us and the Sun, we are a bit further away from the Sun, and vice-versa.

The "barycenter" (the centre of gravity of the Earth-Moon pair) follows are more regular path.

Evan at that, the average distance of the barycenter's orbit does change a bit.  The major culprit is Jupiter, but the other planets also contribute a tiny bit.

The difference is not much (compared to the size of our planet) but it is still counted in hundreds of kilometres from year to year -- sometimes we get closer, sometime we move further away.

Then there is the problem of what we call the orbital period.

In relation to the fixed stars, our exact orbital period is 365.256363 days (of 86,400 seconds each).

That is 365 d 6 h 09 m 10 s

If you start your year at the stroke of midnight on Jan. 1, then at midnight on the next Jan. 1 (on a normal 365 day year), you will have done only 360*(365 / 365.256363) = 359.74733 degrees;

you'll be missing 0.25267 deg. (= 15' 10").

An easier way to say it: you will have missed by 6 h 09 m 10 s.

Answer 5

no because it could be 366 day if its a leap year but 365 if its not a leap year