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.
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.
Kepler discovered that the planets orbit the Sun in elliptical shapes. This means that their orbits are not perfect circles, but instead are stretched out ovals with the Sun located at one of the foci of the ellipse.
Astronomers
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.
Astronomers use a telescope to view planets directly.
Teams of astronomers have studies all possible planets.
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.
Newton learned that the orbits of planets are the result of the gravitational force between the planet and the Sun, which causes the planet to move in an elliptical orbit, and the planet's inertia, which causes it to continue moving in a straight line.
Planets travel in 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.
Many astronomers, historians, regular people, and scientisis know about the planets in our Solar system.
astronomers
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.