Photo of planets in order. : Planets. Planets: The planet count in our solar system has gone as high as 15 before new discoveries prompted a fine tuning of the definition of a planet.
The most recent change was in 2006 when scientists reclassified Pluto as a new kind of object - a dwarf planet. Planets. The planets were thought by Ptolemy to orbit Earth in deferent and epicycle motions.
Although the idea that the planets orbited the Sun had been suggested many times, it was not until the 17th century that this view was supported by evidence from the first telescopic astronomical observations, performed by Galileo Galilei. By careful analysis of the observation data, Johannes Kepler found the planets' orbits were not circular but elliptical. As observational tools improved, astronomers saw that, like Earth, the planets rotated around tilted axes, and some shared such features as ice caps and seasons. Since the dawn of the Space Age, close observation by space probes has found that Earth and the other planets share characteristics such as volcanism, hurricanes, tectonics, and even hydrology. History. The Nine Planets Solar System Tour. The Solar System. Our solar neighborhood is an exciting place.
The Solar System is full of planets, moons, asteroids, comets, minor planets, and many other exciting objects. Learn about Io, the explosive moon that orbits the planet Jupiter, or explore the gigantic canyons and deserts on Mars. What Is The Solar System? The Solar System is made up of all the planets that orbit our Sun.