Solar System Facts for Kids: Look up on a clear night, and you’re already connected to something extraordinary. Our solar system stretches roughly 9 billion kilometres from the Sun to the edge of Neptune’s orbit, yet every planet, moon, asteroid and comet in that vast space follows the same physical rules your child learns about in Year 5 science.
Understanding the solar system isn’t just fascinating; it’s part of the UK National Curriculum and opens the door to asking bigger questions about how our universe works. LearningMole brings this topic to life through curriculum-aligned video resources and explanations designed specifically for primary-aged children and their teachers.
The solar system is often where children first catch the science bug. There’s something uniquely gripping about the sheer scale of it: one million Earths could fit inside the Sun, yet the Sun itself is just an average-sized star in a galaxy of 200 billion stars. For KS2 teachers, this is rich material; it connects directly to Earth and Space objectives in Year 5, supports scientific enquiry skills, and gives children the kind of “wow” moment that sticks. For parents exploring the topic at home, it’s equally rewarding, because space facts are easy to share, easy to visualise, and genuinely surprising at any age.
This guide covers the eight planets in order, five remarkable space facts worth knowing, dwarf planets, how the solar system formed, and how all of this connects to what children study in school. Whether you’re planning a lesson, helping with homework, or simply curious alongside your child, you’ll find clear explanations, a planet fact file, and practical teaching ideas throughout.
Space genuinely surprises people, and these five facts are a reliable starting point. Each one connects to something children encounter in Key Stage 2 science and can spark a classroom discussion or a home learning conversation.
1. One million Earths could fit inside the Sun. The Sun accounts for 99.8% of all the mass in the solar system. It’s so large that roughly one million planet Earths could fit inside it. Yet astronomers classify it as a “yellow dwarf”, an average-sized star. This gives children a sense of just how vast other stars must be, and why the Sun’s gravity is strong enough to hold eight planets in orbit.
2. Venus spins in the opposite direction to most planets. Most planets rotate anticlockwise when viewed from above the Sun’s north pole. Venus rotates clockwise, meaning the Sun rises in the west and sets in the east on Venus. Scientists believe a massive collision billions of years ago may have flipped its rotation.
3. Sound cannot travel through space. Space is a vacuum — there are no air molecules to carry sound waves. This connects to KS2 learning about sound and how it travels through different materials, and it surprises children who expect space to be as noisy as science fiction films suggest.
4. Jupiter acts as Earth’s shield. Jupiter’s enormous gravitational field attracts many asteroids and comets that might otherwise travel towards the inner solar system. Understanding this helps children appreciate that the solar system is a connected system, not just eight separate planets.
5. Footprints left on the Moon will last for millions of years. The Moon has no atmosphere, wind or weather to erode its surface. The footprints left by Apollo astronauts in 1969 are still there and are expected to survive for up to 100 million years. This links neatly to KS2 work on erosion and weathering.
Our solar system contains eight planets, each orbiting the Sun in an elliptical orbit. The order from closest to furthest from the Sun is: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. A useful mnemonic is: My Very Educated Mother Just Served Us Noodles.
| Planet | Type | Avg Temp (°C) | Moons | Distance from Sun (million km) |
|---|---|---|---|---|
| Mercury | Rocky | 167 (day), −183 (night) | 0 | 57.9 |
| Venus | Rocky | 464 | 0 | 108.2 |
| Earth | Rocky | 15 | 1 | 149.6 |
| Mars | Rocky | −65 | 2 | 227.9 |
| Jupiter | Gas giant | −110 (cloud tops) | 95 | 778.5 |
| Saturn | Gas giant | −140 (cloud tops) | 146 | 1,432 |
| Uranus | Ice giant | −195 (cloud tops) | 28 | 2,867 |
| Neptune | Ice giant | −200 (cloud tops) | 16 | 4,515 |
The eight planets fall into two main groups. The terrestrial planets (Mercury, Venus, Earth and Mars) are rocky, relatively small, and sit closer to the Sun. The gas and ice giants (Jupiter, Saturn, Uranus and Neptune) are much larger, composed mainly of gases and ices, and orbit much further out.
Why do planets have different colours? Colour depends on what a planet’s surface or atmosphere is made of and how it reflects sunlight. Mars looks red because its surface contains iron oxide (rust). Jupiter’s banded appearance comes from different layers of gases, including ammonia clouds. Earth appears blue from space largely because of its oceans.
Astronomers usually divide the eight planets into two distinct categories based on what they are made of:
Pluto was classified as the ninth planet until 2006, when the International Astronomical Union (IAU) introduced a formal definition of what a planet must be. Under this definition, a planet must orbit the Sun, have enough gravity to pull itself into a roughly spherical shape, and have cleared the area around its orbit of other debris. Pluto meets the first two conditions but not the third — its orbital neighbourhood is still full of other Kuiper Belt objects. So Pluto was reclassified as a dwarf planet.
There are currently five recognised dwarf planets in our solar system:
For children, the Pluto question is a genuinely good critical thinking exercise: What makes something a planet? Why do definitions in science change? This kind of discussion develops scientific enquiry skills that go beyond rote learning.
The solar nebula theory is the most widely accepted explanation for how our solar system came to exist. Around 4.6 billion years ago, a large cloud of gas and dust (called a nebula) began to collapse under its own gravity. As it collapsed, it started to spin. Most of the material fell to the centre, heating up and eventually forming the Sun. The remaining material flattened into a disc around the Sun, and within that disc, particles began to clump together. Over millions of years, these clumps grew into the planets, moons, asteroids and comets we see today.
Several features of our solar system support this theory:
New technologies have strengthened the evidence. The Hubble Space Telescope has observed stars and planetary systems forming from nebulae in real time, confirming that star formation is an ongoing process across the universe.
“Children are naturally curious about how things began, the solar system gives us a story that’s both scientifically grounded and genuinely awe-inspiring. Starting with the formation question helps children see science as a way of answering the biggest questions there are.” Michelle Connolly, Founder of LearningMole and former teacher with over 15 years of classroom experience
The solar system sits within the Year 5 Science unit on Earth and Space, part of KS2. The national curriculum objectives require pupils to describe the movement of the Earth and other planets relative to the Sun, describe the movement of the Moon relative to the Earth, describe the Sun, Earth and Moon as approximately spherical bodies, and use the idea of the Earth’s rotation to explain day and night.
This article covers the core knowledge underpinning those objectives. The planet fact file table, the solar system formation section and the facts about Venus’s rotation are directly useful for classroom lesson content. The topic also supports Working Scientifically skills at KS2, particularly gathering and presenting findings in tables, drawing conclusions from evidence, and using correct scientific language. Key vocabulary to display in KS2 classrooms covering this unit: terrestrial, gas giant, orbit, rotation, revolution, vacuum, nebula, dwarf planet.
LearningMole provides curriculum-aligned video resources that bring Earth and Space to life for primary-aged children. The video below introduces solar system facts in an accessible, engaging way for KS2 learners, suitable for whole-class viewing or independent home learning.
For teachers, LearningMole’s educational resources cover the full range of KS2 science topics, with video explanations that support classroom teaching. Visual explanations of abstract concepts like planetary orbits and the scale of the solar system help children build the mental models they need before moving to more formal work.
For parents, the videos work well alongside homework or as an extension activity for curious children who want to go further. LearningMole’s teaching materials are designed by experienced educators and aligned to UK National Curriculum objectives, making them straightforward to integrate into lesson planning.
Explore LearningMole’s science resources | Watch free educational videos on YouTube
The eight planets in order from closest to furthest from the Sun are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. The mnemonic “My Very Educated Mother Just Served Us Noodles” helps children remember the order. Pluto was reclassified as a dwarf planet in 2006 and is no longer counted among the main eight. In the UK National Curriculum, children cover planetary order as part of the Year 5 Earth and Space unit.
Venus is the hottest planet, with surface temperatures reaching around 464°C — hot enough to melt lead. This surprises many children because Mercury is closer to the Sun. Venus is hotter because of its thick carbon dioxide atmosphere, which traps heat through the greenhouse effect. This connects the solar system topic usefully to climate science concepts.
Pluto is now classified as a dwarf planet, a category introduced by the International Astronomical Union in 2006. To be a full planet, a body must orbit the Sun, be spherical due to its own gravity, and have cleared its orbital neighbourhood of other objects. Pluto meets the first two conditions but not the third. For children, this is a good example of how scientific classifications change as knowledge improves.
Neptune’s orbit is roughly 4.5 billion kilometres from the Sun, but the gravitational influence of the Sun extends much further, reaching the Oort Cloud at perhaps 100,000 times Earth’s distance from the Sun. Scale models are the most powerful classroom tool for grasping these distances. A model where the Sun is a grapefruit places Neptune roughly 235 metres away, demonstrating that the solar system is mostly empty space.
Rotation refers to a planet spinning on its own axis, which causes day and night on Earth. A revolution is a planet’s orbit around the Sun, which gives us a year. Earth takes 24 hours to rotate once and 365.25 days to complete one revolution. These two terms are often confused by children, and physical demonstrations work well: spinning on the spot (rotation) versus walking a circuit around a lamp (revolution).
The solar system is the core topic within Year 5 Earth and Space in the KS2 science curriculum. It introduces children to gravity, orbital motion, day and night, and the scale of the universe. It also provides excellent opportunities for Working Scientifically skills: research, data presentation in tables, and drawing conclusions. LearningMole’s video resources on the solar system support teachers covering this unit with age-appropriate, curriculum-aligned explanations.
Start with scale. Making a simple model using fruit or balls of different sizes is far more effective than just reading about it. Then use reliable video resources to add detail and context. The key facts worth establishing at home are: the order of the planets (the mnemonic helps), why we have day and night (Earth’s rotation), and the difference between a planet and a dwarf planet. LearningMole’s educational videos cover all of these in child-friendly language.
The solar nebula theory explains how our solar system formed roughly 4.6 billion years ago. A large cloud of gas and dust collapsed under gravity, began to spin, and flattened into a disc. The centre became the Sun; the rest of the material gradually clumped together to form the planets, moons and other bodies. Evidence supporting this theory includes the fact that all planets orbit in the same direction and in roughly the same plane, and observations of other stars forming in similar ways have been made using the Hubble Space Telescope.
Our solar system is one of the most powerful entry points into science education. The scale is awe-inspiring, the facts are memorable, and the curriculum connections are direct. Children who understand how the planets differ from each other, why Pluto was reclassified, and how day and night work are building a foundation that supports physics, chemistry and earth science right through secondary school and beyond.
For teachers, the solar system topic rewards investment. The Year 5 Earth and Space unit is one where hands-on demonstrations, visual resources and well-chosen facts can transform abstract curriculum content into something children genuinely remember. The planet fact file, formation story and the five key facts in this guide are all designed to be classroom-ready without requiring extensive preparation.
LearningMole supports teachers and parents across the UK with curriculum-aligned resources for primary science and beyond. Whether you’re revisiting a topic or teaching it for the first time, clear, accurate content that respects children’s intelligence and curiosity makes all the difference. Space is a topic that earns its place in the curriculum precisely because it does something rare: it makes children want to know more.
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