Describe the Solar System as containing: (a) one star, the Sun (b) the eight named planets and know their order from the Sun (c) minor planets that orbit the Sun, including dwarf planets such as Pluto and asteroids in the asteroid belt (d) moons, tha

6.1.2 The Solar System 🌞

The Sun – Our Central Star ☀️

The Sun is a G‑type main‑sequence star with a mass of about \$1.989 \times 10^{30}\,\text{kg}\$ and a radius of \$6.96 \times 10^5\,\text{km}\$. It supplies the energy that keeps the planets warm and drives all the weather and climate we see on Earth.

The Eight Planets – From Mercury to Neptune 🪐

1. Mercury – the closest to the Sun, a rocky world with no atmosphere.
2. Venus – a hot, dense atmosphere, often called Earth’s “sister planet.”
3. Earth – our home, the only planet known to support life.
4. Mars – the Red Planet, with polar ice caps and a thin CO₂ atmosphere.
5. Jupiter – the gas giant, 318 times Earth’s mass, with a famous Great Red Spot.
6. Saturn – known for its spectacular rings made of ice and rock.
7. Uranus – an ice giant that spins on its side.
8. Neptune – the farthest planet, a blue world with strong winds.

Minor Planets & Dwarf Planets 🌌

Minor planets are bodies that orbit the Sun but are not classified as the eight major planets. They include:

• Dwarf planets – bodies that are spherical but have not cleared their orbit (e.g., Pluto, Eris, Haumea).
• Asteroids – rocky fragments mostly found in the Asteroid Belt between Mars and Jupiter.
• Comets – icy bodies that develop glowing comas and tails when they approach the Sun.

Asteroid Belt – The Rocky Road 🪨

The Asteroid Belt is a ring of debris roughly 2–4 AU from the Sun. It contains millions of asteroids, the largest of which is Ceres, a dwarf planet. Think of it as a cosmic traffic jam of rocks that never formed into a planet because Jupiter’s gravity kept pulling them apart.

Moons – Planetary Satellites 🌙

Every planet (except Mercury and Venus) has at least one moon. Some, like Earth’s Moon, are large enough to be seen with the naked eye. Others, like the dozens of moons orbiting Jupiter and Saturn, are smaller but still crucial for understanding planetary formation.

Comets & Other Small Bodies 🌠

Comets are icy bodies that develop bright comas and tails when they get close to the Sun. They come from the Kuiper Belt and Oort Cloud, the outermost reservoirs of the Solar System. Other small bodies include meteoroids (tiny rock fragments) and space dust.