16A
Section 1: components of the inner and outer solar system
A planet is a celestial body with sufficient mass to withstand rigid body forces, achieve hydrostatic
equilibrium, and acquire a roughly spherical shape as it travels through space. Our solar system is
made up of the Sun, Pluto, numerous moons, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus,
Neptune, asteroids, comets, and meteoroids.
Mercury
The smallest and nearest planet to the Sun in the Solar System is Mercury. The quickest of the Sun's
planets, its orbit takes place in 87.97 Earth days.
Venus
Venus is the planet that is closest to the Sun. Because of its size and similarity to Earth in
composition, it is frequently referred to as Earth's "twin" or "sister" planet. Whether Venus is visible
in the morning or evening sky, it is always close to the Sun. Venus is an inner planet to Earth.
Earth
Earth is the only planet in our solar system having liquid water on its surface. Earth is the largest of
the four planets nearest to the Sun, all of which are composed of rock and metal, and is only slightly
larger than Venus.
Mars
Mars is a planet with seasons, polar ice caps, canyons, dead volcanoes, and clues to its once-higher
level of activity. The second-smallest planet in the Solar System, it orbits at a distance of four planets
from the Sun. Mars is also a frigid, arid, sandy planet with a thin atmosphere.
Jupiter
The largest planet in the Solar System, Jupiter, is the fifth planet from the Sun. It is a gas giant with a
mass that is slightly less than one thousandth that of the Sun and more than two and a half times
that of all the other planets in the Solar System put together.
Saturn
The second-largest planet in the Solar System, Saturn is located six planets from the Sun. With an
average radius of almost nine and a half times that of Earth, it is a petrol giant. Being nearly 95 times
more massive, it barely possesses an eighth of Earth's average density.
Uranus
Uranus, which is the seventh planet from the Sun, has the third-largest diameter. First believing it to
be either a comet or a star, astronomer William Herschel discovered Uranus in 1781, making it the
first planet to be spotted with the use of a telescope.
Neptune
Neptune, the outermost planet in the solar system, is eight planets away from the Sun. It ranks
fourth in terms of diameter and third in terms of mass and density among the planets in the Solar
System. It has a mass 17 times greater than Earth's and is heavier than Uranus.
Planets Composition
Mercury Rocky, iron
Venus Rocky, carbon dioxide, nitrogen, iron core
, Earth Rocky, iron, nickel
Mars Rocky, iron, nickel, sulfur,
Jupiter Gaseous, Trapped helium, hydrogen, water
Saturn Gaseous, Hydrogen, helium
Uranus Gaseous Water, methane, ammonia
Neptune Gaseous, Water, methane, ammonia
Dwarf planets Composition
Pluto Rocky, water, ice
Haumea Rocky, coating of ice
10 Hygiea Rocky asteroid,
Ceres Rocky crust, water, ice, carbonates, clay
Makemake Rocky, ice, frozen methane, nitrogen
90377 Sedna Water, methane, nitrogen ices
Eris Rocky, (50% pure methane ice), methane,
nitrogen, water ices, ice tholin
50000 Quaoar Ice mixed with rock
225088 Gonggong Rocky, water, ice