Solar System: quick revision, 12 bites

One Star, Eight Planets, One Moon

Our cosmic neighbourhood in one line.

The **Solar System** is the Sun and everything bound to it by gravity. It has **one star (the Sun)**, **eight planets**, their moons, dwarf planets, asteroids and comets. Earth's only natural satellite is the **Moon**.

Takeaway. Sun at the centre, eight planets around it, one Moon for Earth.

What Is the Sun?

The engine of the whole system.

The **Sun** is a medium-sized star made mostly of **hydrogen** and **helium**. It is the closest star to Earth and the source of almost all light and heat in the Solar System.

Takeaway. The Sun is a star — the Solar System's power source.

Eight Planets in Order

Mercury to Neptune, in sequence.

The first four are **inner (rocky) planets**; the last four are **outer (giant) planets**.

Takeaway. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

Inner vs Outer Planets

Rocky close in, giants far out.

Takeaway. Inner = small and rocky; outer = big and gassy.

Earth: The Living Planet

The only known home of life.

**Earth** is the third planet from the Sun and the only planet known to support **life**. It has **one natural satellite — the Moon** — and takes about **365 days** to orbit the Sun.

Takeaway. Earth is the third planet and the only known living world.

The Moon

Earth's silent companion.

The **Moon** is Earth's only natural satellite. It has **no light of its own** — it shines because it **reflects sunlight**. It has no atmosphere and no life.

Takeaway. The Moon shines by reflecting sunlight, not by itself.

Why We See Moon Phases

Same Moon, changing shapes.

The Moon does not change shape. As it **orbits Earth**, the Sun lights different portions of its surface, so we see different **phases**.

Takeaway. Phases are about viewing angle, not the Moon changing.

Gravity Holds It Together

The invisible glue of space.

**Gravity** is the force that keeps planets in orbit around the Sun and moons in orbit around planets. The Sun's huge mass makes it the strongest gravitational anchor in the system.

Takeaway. Gravity keeps every orbit in place.

Day and Night

Why the sky goes dark.

Earth **rotates** on its axis once about every **24 hours**. The side facing the Sun has **day**; the side turned away has **night**.

Takeaway. Rotation of Earth gives us day and night.

Remember the Planet Order

A sentence that sticks.

Use the classic mnemonic: **My Very Educated Mother Just Served Us Noodles** — Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

Takeaway. One silly sentence locks in eight planets.

Jupiter Is the Giant

The biggest planet of all.

**Jupiter** is the **largest planet** in the Solar System. **Mercury** is the **smallest** and the **closest to the Sun**.

Takeaway. Jupiter biggest, Mercury smallest and nearest.

Exam Pointers

Score-safe facts to quote.

Takeaway. Five facts that cover most Solar System questions.