Tycho was the first astronomer to make measurements of enough accuracy to show that the older theories were producing errors in the planets' positions.
The difference between an ellipse and the old model of a circle and epicycle, which gives a circle with the Sun off-centre, was so small that it needed high accuracy to notice the difference. Planets' orbits have an extremely small difference between the major and minor axes of the ellipses.
elliptical
I don't know what "elliptical planet" is supposed to mean, but by any reasonable definition I can think of, no, all planets are "elliptical planets".
All planets have elliptical orbits.
Astronomers.
All the planets have elliptical orbits but Uranus and Neptune have slightly different orbits than other planets on solar system.
He is a danish astronomer who stated that all the planets revolve around the sun in elliptical orbits and that the sun is not in the exact center of the orbit.
Tycho was the first astronomer to make measurements of enough accuracy to show that the older theories were producing errors in the planets' positions. The difference between an ellipse and the old model of a circle and epicycle, which gives a circle with the Sun off-centre, was so small that it needed high accuracy to notice the difference. Planets' orbits have an extremely small difference between the major and minor axes of the ellipses.
Teams of astronomers have studies all possible planets.
Astronomers use a telescope to view planets directly.
All the planets move with an elliptical orbit, but with a very low eccentricity.
elliptical
I don't know what "elliptical planet" is supposed to mean, but by any reasonable definition I can think of, no, all planets are "elliptical planets".
It was Kepler who discovered that the planets orbits are elliptical.
All planets have elliptical orbits.
When a planet moves around a star, it causes the star to wobble a bit from side to side as planets follow an elliptical orbit rather than a circular orbit. Astronomers can then use this fact to see whether stars have planets.
Planets travel in elliptical orbits.
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.