Why is the earths orbit not round?

Answer 1

Have you ever played with a child's spinning top or a gyro. Set then spinning and you will notice that the axis that touches the ground moves. Watch it more closely, that movement forms an ellipse that doe not quite close up, an ellipsoid. The planets do exactly the same in space about the Sun.

Also over many years (orbits) the ellipsoid can become narrow(elongated) and then start to 'fatten' out to becomes nearly circular, and then elongate again. It constantly repeats. It thought that these elliptical changes will affect the amount of solar radiation received the planets (Earth included). Consequently it may effect climate change.

In this elliptical manner the Sun lies at one of the foci of the ellipse, NOT the centre. The other focus may be described as 'Blind' focus.

Also in playing with a spinning top or gyro, you will also notice that the axis 'wobbles'. The Earth's axis does exactly the same, currently it is 23.5 degrees, and reducing to about 20 degrees, and then will increase again to about 28 degrees. This again occurs over many thousands of years, but will affect the amount a solar radiation , and thereby climate change.

Answer 2

The Earth's orbit is technically an ellipse, but practically speaking it is almost a perfect circle.

The eccentricity measures how much of an ellipse the orbit is, and an ellipse whose eccentricity equals exactly zero is a circle.

The eccentricity of the Earth's orbit is 1/60, which means the Sun is off-centre by one sixtieth of the radius.

The mean radius is 149.6 million km, so the Sun is 2.5 million km off-centre. That means our distance varies from 147.1 to 152.1 million km.

The shape of the ellipse is nearly a circle and in fact the minor axis is 99.986% as large as the major axis

Answer 3

The only practical way to answer that question in this particular forum is simply:

That's the way gravity works.

The way gravity works ...

-- Every closed orbit of one body around another one with much greater mass is

an ellipse.

-- The size of the ellipse depends on how much energy the smaller body has.

-- For any particular enegy/size, there are an infinite number of possible shapes

for the ellipse. Some are skinnier, some are fatter, and only ONE is a circle.

Answer 4

Because its cool like that