Because It Has To Spin Like Planets Do
On its axis Earth rotates around the sun.
yes
Yes, Earth does spin on its own axis. The axis is on a tilt of 23.5 degrees by memory.
Yes, Mercury does rotate about its own axis. However, its rotation is unique in that it is in a 3:2 spin-orbit resonance, meaning it rotates on its axis three times for every two orbits around the Sun.
If by spin you mean "rotate daily" then yes. But you could refer to our "orbit" as a spin around the sun. But if you want to refer to "spin" as any oscillatory/periodic motion of the earth, then we spin around our central axis, we orbit around the sun, we precess the rotational axis around a precession axis, our obliquity oscillates periodically and our eccentricity oscillates around the foci of our elliptic orbit which is near the center of the sun. These characteristics of our orbit are known as the Milankovic cycles.
365 days in a year 366 days in a leap year.
One day equals one spin on earth's axis.
25 days
Venus.
No the sun does not have a twin. It rotates on its own axis.No, the sun does not have a twin. It is on its own, rotating in its own axis.
Rotation refers to spin around the axis.
If by revolution you mean the spin on it's own axis this is more or less a perfect circle. If you are referring to it's orbit around the sun, this is elliptical, not a perfect circle.