Can earth be regarded as a point object when it is describing its yearly journey around the sun?

The motion of earth around the sun is-

What remains constant when the earth revolves around the sun?

What is the direction of areal velocity of the earth around the sun?

Earth can be thought of as a sphere of radius 6400 km.Any object (or a person) is pewrforming circular motion around the axis of the earth due to the earth rotation (period 1 day). What is acceleration of object on the surface of the earth (at equator) towards its centre? What is it at latitude theta ? How does these acceleration compare with g = 9.8 m//s^(2) ?

The nearest star to our solar system is 4.29 light years away. How much is this distance in terms of parsecs? How much parallax would this star (named Alpha Centauri) show when viewed from two locations of the Earth six months apart in its orbit around the Sun ?

What provides the centripetal force in the following cases earth revolving around the sun