# Thread: Is one revolution around the Sun called a solar year or a sidereal year?

1. ## Is one revolution around the Sun called a solar year or a sidereal year? var addthis_config = {"data_track_clickback":false};

I'm still confused and in the last question I got a total different answer than expected and it's not what I meant the last time. When the Earth is orbiting the Sun in the same place it was the previous year, has it been a solar year or a sidereal year?

2. Actually it doesnt happen.
Everytime when is Earth is rotating around the sUn..The position is same when you consider relativity (Relative to position of Sun)
But practically,Universe is expanding, Sun is rotating in its axis.
Its just one Human year added to your age when Earth Finishes on rotation

3. A sidereal year to how long it takes for the earth to orbit the sun once as measured against the fixed background stars. This differs from a solar year because the earth's rate of rotation is of course not perfectly in sync with its rate of revolution.

4. I you were outside the solar system, looking at it, say at a nearby star such as Alpha Centauri, and were observing the earth and sun through a telescope, you would see the earth going around the sun. When it got back to its original position, that would be one sidereal year. Sidereal means "relative to the stars".

But the earth's axis doesn't always point in the same direction. It spins like a top does when it is losing speed so that the axis draws out a cone at the North pole and a cone at the south pole. This happens very slowly, over a period of 26,500 years. It's called precession. One of the effects of it is that the seasons move on slightly each year. If we start measuring our year on the first day of spring, then after a sidereal year, it is not quite the first day of spring of the next set of seasons.

Since we're more interested in the seasons than in the position of the stars, we extend the year slightly, from the begining of spring to the next beginning of spring. We call this period a tropical year, or sometimes a solar year. It's the one that we consider to be a normal year. It is only a tiny bit longer than the sidereal year.

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts