What is in our The Solar System?
The force of gravity generated by the Sun’s vast mass is a family of planets and other bodies trapped in orbit around it.Together ,the sun and all these bodies make up our Solar System.
Our sun formed from a great cloud of dust and gas around 4.6 billions years ago .vast amounts of matter were drown in by the developing star,but not all of it was fully absorbed .A tiny fraction of leftover material-a mere 0.14 percent of the of the solar system’s mass-formed a disc of gas and dust encircling the newborn star .over millions of years ,the grains of dust in this disc clumped together,growing into ever larger bodies until they grew to the size of planets pulled into spheres by their own gravity. In the inner solar system ,where the sun’s heat was too intense for gases to condense to form much bigger planets.
Today the solar system has eight planets,more than 100 moons,an unknown number of dwarf planets and countless millions of comets and asteroids.
The solar system’s planets from two there are four small,inner planets made of rock and metal,four giant ,outer planets made of gas and liquid .Between the two is a belt of rocky bodies called asteroids,and beyond the planets is a zone of icy bodies including dwarf planets and comets. Even further out is a vast, spherical cloud of more comets-the Oort cloud .the solar system has no agreed outer boundary.
- Asteroid
Asteroid are giant rocks that drift around the inner solar system most lie in a belt between mars and Jupiter,but some occasionally come dangerously close to earth .the smallest are the size of houses,while ,the largest are big enough to be classed as dwarf planets .Scientists think asteroid are leftovers from the materials that formed the planets .all of them together amount to less than a twentieth of the moon's mass.
- ORBIT
every major body in the solar system orbit the sun anticlockwise .the planets are on the near-circular orbit in the same plane as the disc off gas and dust from which they formed .many smaller object,such as dwarf planets pluto and eris,have stretched orbit titled to this plane .comets arrive from all direction.
How orbit work
English scientist Isaac Newton was the first person to realize why moons and planets travel in orbits:because they are trapped by gravity .to explain his theory ,he drew a giant cannon firing cannonballs off earth .if a cannonballs moved fast enough ,the curve of its path asif fell back would be gentler than the curve of earth’s shape ,and it would never land-it would stay in orbit.
- Dwarf Planets
Dwarf planets are round in shape but smaller than
true planets ,and their gravity is not strong enough to sweep their region of space debris.The most famous dwarf planet is pluto which was classed as a true planet until 2006.see Also :
Planets in our Solar System
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