solar systemname and description for kids 1st grade

Various small-body populations, including comets, centaurs and interplanetary dust clouds, freely travel between the regions of the Solar System. Astronomers generally accept about nine objects as dwarf planets: the asteroid Ceres, the Kuiper-belt objects Pluto, Orcus, Haumea, Quaoar and Makemake, the scattered-disk objects Gonggong and Eris, and Sedna. Some of these objects are large enough to have rounded under their own gravity and thus to be categorized as dwarf planets.

There is considerable debate as to how many such objects there will prove to be. In the outer reaches of the Solar System lies a class of minor planets called detached objects. Beyond Neptune's orbit lie the Kuiper belt and scattered disc, which are populations of objects composed mostly of ice and rock. The asteroid belt, which lies between the orbits of Mars and Jupiter, contains objects composed of rock, metal and ice. Each of the giant planets and some smaller bodies are encircled by planetary rings of ice, dust and moonlets. Two natural satellites, Jupiter's moon Ganymede and Saturn's moon Titan, are larger but not more massive than Mercury, the smallest terrestrial planet, and Jupiter's moon Callisto is nearly as large. Six of the major planets, the six largest possible dwarf planets, and many of the smaller bodies are orbited by natural satellites, commonly called 'moons' after Earth's Moon. There are an unknown number of smaller dwarf planets and innumerable small Solar System bodies orbiting the Sun. All eight planets have nearly circular orbits that lie near the plane of Earth's orbit, called the ecliptic. The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium the next two, Uranus and Neptune, are ice giants, being composed mostly of volatile substances with relatively high melting points compared with hydrogen and helium, such as water, ammonia, and methane. The four giant planets of the outer system are substantially larger and more massive than the terrestrials. The four inner system planets- Mercury, Venus, Earth and Mars-are terrestrial planets, being composed primarily of rock and metal. The vast majority (99.86%) of the system's mass is in the Sun, with most of the remaining mass contained in the planet Jupiter. It formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The Solar System is the gravitationally bound system of the Sun and the objects that orbit it.

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Solar systemname and description for kids 1st grade