It takes five good observations to find the orbital elements for a planet. The observations need to be taken over enough time for the planet to cover a good fraction of the orbit. That allows an ellipse to be fitted to the measurements.
Yes. They orbit the Sun and as per Kepler's first law they follow an elliptical path. Do note that a circular orbit is a special type of elliptical orbit.
As an elliptical orbit is any orbit that isn't perfectly circular, everything has an elliptical orbit. The planets Mercury and Pluto have the most elliptical orbits of the planets, and are easily seen to be oval shaped. Comets also have highly elliptical orbits.
All the planets move with an elliptical orbit, but with a very low eccentricity.
The planet with the most elliptical orbit is Mercury. Second is Mars.
Mars has the most elliptical orbit. The earth's is almost a perfect circle
elliptical
Yes, the distance from the sun is variable for anything with an elliptical orbit.
The Earth has an elliptical orbit around the Sun.
All planets have elliptical orbits.
Elliptical Orbit
It is described as a large elliptical orbit.
It is called an elliptical orbit.