Top 101 Easy Solar System Facts for Kids

Eight planets. One star. Billions of kilometres of space in between. The Solar System is the most dramatic neighbourhood in the known universe, and children are naturally curious about every part of it. Whether a pupil wants to know why Pluto lost its planet status, how hot Venus really gets, or what astronauts ate on the International Space Station, the answers are here in plain, accurate language that matches what UK primary schools teach.

This guide gives you exactly 101 numbered, one-sentence facts organised by topic, from the Sun and each planet to dwarf planets, space exploration and a section dedicated to Year 5 Earth and Space objectives in the UK National Curriculum. Every distance is given in kilometres, not miles, so teachers can use these facts directly on worksheets without converting units. The guide also includes two reference tables, a set of classroom-tested planet mnemonics, and eight FAQ answers written to the depth children and parents actually need.

LearningMole, the UK educational platform founded by former primary teacher Michelle Connolly, produced this guide to give teachers and parents a single, reliable resource for space topics at Key Stage 2. Whether you are planning a Year 5 science unit, supporting homework at home, or building a display for World Space Week, these facts are curriculum-checked and written for children aged 7 to 11.

The Solar System at a Glance

The table below provides a quick reference profile of all eight planets. Use it as a classroom display, a homework reference, or the starting point for a comparison activity.

Planet	Distance from Sun	Avg. Temp.	Moons	Day Length	Year Length
Mercury	57.9 million km	+167°C	0	59 Earth days	88 Earth days
Venus	108.2 million km	+464°C	0	243 Earth days	225 Earth days
Earth	149.6 million km	+15°C	1	24 hours	365 days
Mars	227.9 million km	-65°C	2	24h 37min	687 Earth days
Jupiter	778.5 million km	-110°C	95	9h 56min	12 Earth years
Saturn	1,434 million km	-140°C	146	10h 42min	29 Earth years
Uranus	2,871 million km	-195°C	28	17h 14min	84 Earth years
Neptune	4,495 million km	-200°C	16	16h 6min	165 Earth years

Note: Moon counts reflect confirmed totals as of 2024. Saturn’s total rose to 146 confirmed moons following discoveries announced in May 2023.

The Centre of It All: The Sun (Facts 1–10)

The Sun is not just one of many objects in the Solar System. It contains 99.8% of all the mass in the entire system, and its gravitational pull holds every planet, moon, comet and asteroid in place. Everything else orbits it.

1. The Sun is a star, not a planet, made mainly of hydrogen and helium gas.
2. The Sun is approximately 4.6 billion years old and is expected to keep burning for another five billion years.
3. The Sun’s surface temperature is around 5,500 degrees Celsius, but its outer atmosphere, the corona, reaches over one million degrees Celsius.
4. Light from the Sun takes approximately eight minutes to travel the 149.6 million kilometres to Earth.
5. The Sun makes up 99.8% of the total mass of the Solar System.
6. Sunspots are cooler, darker patches on the Sun’s surface caused by intense magnetic activity.
7. The Sun rotates on its axis, but because it is made of gas, different parts rotate at different speeds.
8. Solar flares are explosions on the Sun’s surface that can disrupt satellites and radio signals on Earth.
9. The Sun controls Earth’s seasons, tides, weather patterns and agricultural cycles.
10. The Sun is classified as a yellow dwarf star, which is an average-sized star in the context of the wider universe.

The Inner Rocky Planets (Facts 11–40)

Mercury, Venus, Earth and Mars are the four terrestrial planets. They have solid, rocky surfaces, metallic cores and relatively thin atmospheres compared with the gas giants. All four orbit much closer to the Sun than Jupiter and beyond.

Mercury: The Smallest and Fastest (Facts 11–20)

11. Mercury is the smallest planet in the Solar System, slightly larger than Earth’s Moon.
12. A year on Mercury lasts only 88 Earth days, making it the fastest planet to orbit the Sun.
13. A single day on Mercury lasts 59 Earth days, meaning a year is shorter than two of its own days.
14. Mercury has no moons and no significant atmosphere to trap heat.
15. Surface temperatures on Mercury swing from -180 degrees Celsius at night to 430 degrees Celsius during the day.
16. Mercury is named after the swift-footed messenger of the gods in Roman mythology.
17. Mercury has a very large iron core that makes up about 85% of its radius.
18. The planet’s surface is covered in craters caused by billions of years of impacts with space rocks.
19. Mercury is slowly shrinking as its iron core cools and contracts.
20. Mercury lies 57.9 million kilometres from the Sun, making it the closest planet to our star.

Venus: The Hottest Planet (Facts 21–28)

21. Venus is the hottest planet in the Solar System with an average surface temperature of 464 degrees Celsius.
22. Venus is hotter than Mercury because its thick atmosphere of carbon dioxide traps the Sun’s heat.
23. A day on Venus lasts 243 Earth days, which is longer than its year of 225 Earth days.
24. Venus spins in the opposite direction to Earth, so the Sun rises in the west and sets in the east on Venus.
25. Venus has no moons.
26. Venus is the third brightest object in Earth’s sky after the Sun and the Moon.
27. The air pressure on Venus is 90 times greater than on Earth’s surface.
28. Venus is sometimes called Earth’s twin because the two planets are nearly the same size and made of similar materials.

Earth: Our Home in Space (Facts 29–34)

29. Earth is the only planet in the Solar System known to support life.
30. About 70% of Earth’s surface is covered by water, which is why it looks blue from space.
31. Earth has one natural satellite: the Moon, which is the fifth-largest moon in the Solar System.
32. Earth completes one full orbit of the Sun in 365.25 days, which is why we add an extra day in leap years.
33. Earth’s atmosphere has six layers, with the troposphere at the bottom, where weather occurs.
34. Earth’s magnetic field is generated by its molten iron core and protects us from harmful solar radiation.

Mars: The Red Planet (Facts 35–40)

35. Mars is called the Red Planet because its soil and dust contain iron oxide, which gives it a reddish colour.
36. Mars has the tallest volcano in the Solar System, Olympus Mons, which stands 21 kilometres high.
37. Mars has two small moons, Phobos and Deimos, both believed to be captured asteroids.
38. A day on Mars is only 37 minutes longer than an Earth day, which is why scientists call it a “sol”.
39. Mars once had liquid water on its surface and may have had conditions suitable for microbial life billions of years ago.
40. Mars has the largest dust storms in the Solar System, which can cover the entire planet for months.

The Outer Gas Giants (Facts 41–70)

Jupiter, Saturn, Uranus and Neptune are the Jovian planets. They are enormous balls of gas and ice with no solid surface to stand on. They have far more moons than the terrestrial planets, and all four have ring systems, though only Saturn’s rings are easily visible from Earth.

Jupiter: King of the Planets (Facts 41–52)

41. Jupiter is the largest planet in the Solar System, with a mass more than twice that of all other planets combined.
42. A day on Jupiter lasts only 9 hours and 56 minutes, the shortest day of any planet.
43. Jupiter has at least 95 confirmed moons, including Ganymede, which is the largest moon in the Solar System.
44. Ganymede is larger than the planet Mercury.
45. Jupiter’s Great Red Spot is a storm that has been raging for over 350 years.
46. Three Earths could fit side by side across the Great Red Spot.
47. Jupiter is made mostly of hydrogen and helium and has no solid surface.
48. Jupiter has a faint ring system made of dust particles.
49. Jupiter’s magnetic field is 14 times stronger than Earth’s.
50. Scientists believe it may rain diamonds on Jupiter as atmospheric pressure turns carbon into diamond crystals.
51. Jupiter is 778.5 million kilometres from the Sun.
52. A year on Jupiter equals about 12 Earth years.

Saturn: The Ringed Wonder (Facts 53–60)

53. Saturn has the most spectacular ring system in the Solar System, stretching up to 282,000 kilometres from the planet.
54. Despite their enormous width, Saturn’s rings are only about one kilometre thick.
55. Saturn’s rings are made of ice particles, rock fragments and dust.
56. Saturn has 146 confirmed moons, more than any other planet.
57. Saturn’s moon Titan has a thick atmosphere and lakes of liquid methane on its surface.
58. Saturn is the least dense planet in the Solar System and would float on water if there were an ocean large enough.
59. A year on Saturn lasts approximately 29 Earth years.
60. Saturn is named after the Roman god of agriculture and time.

Uranus: The Tilted Giant (Facts 61–65)

61. Uranus is tilted so far on its axis that it effectively rolls around the Sun on its side.
62. Uranus is the coldest planet in the Solar System, with temperatures dropping to -224 degrees Celsius.
63. Uranus is the only planet named after a Greek god rather than a Roman one.
64. A season on Uranus lasts 42 Earth years because of its extreme tilt.
65. Uranus has 13 known rings and 28 confirmed moons.

Neptune: The Windy World (Facts 66–70)

66. Neptune has the strongest winds in the Solar System, reaching speeds of up to 2,100 kilometres per hour.
67. Neptune is the most distant planet from the Sun, lying 4,495 million kilometres away.
68. A year on Neptune lasts 165 Earth years.
69. Neptune was the first planet to be predicted mathematically before it was directly observed through a telescope.
70. Neptune has 16 confirmed moons, the largest of which is Triton.

Dwarf Planets, Asteroids and Comets (Facts 71–90)

Beyond the eight planets, the Solar System contains millions of smaller objects. Dwarf planets are large enough to be roughly spherical but have not cleared the space around their orbits of other similar objects.

Pluto and the Dwarf Planets (Facts 71–82)

71. Pluto was reclassified from a planet to a dwarf planet by the International Astronomical Union in 2006.
72. Pluto could not qualify as a planet because it has not cleared other objects from its orbital neighbourhood.
73. Pluto takes 248 Earth years to complete one orbit of the Sun.
74. Pluto has five moons, the largest of which, Charon, is about half Pluto’s own size.
75. Pluto has white-capped mountains made of methane frost and peaks made of water ice.
76. There are five officially recognised dwarf planets in the Solar System: Pluto, Eris, Haumea, Makemake and Ceres.
77. Ceres is the largest object in the asteroid belt and the only dwarf planet located in the inner Solar System.
78. Eris is slightly smaller than Pluto and takes 557 Earth years to orbit the Sun.
79. Haumea rotates faster than any other known dwarf planet, completing a full spin in just 3.9 hours.
80. Makemake has one known moon, discovered only in 2016.
81. Scientists believe there may be dozens more dwarf planets in the outer Solar System yet to be officially confirmed.
82. The discovery of Eris in 2005 directly led to Pluto’s reclassification because Eris was initially thought to be larger.

Asteroids, Comets and Meteorites (Facts 83–90)

83. The asteroid belt between Mars and Jupiter contains millions of rocky objects left over from the formation of the Solar System.
84. Most asteroids are irregularly shaped because they are too small for gravity to pull them into a sphere.
85. Comets are made of ice, dust and rock and develop a glowing tail as they approach the Sun and the ice melts.
86. There are approximately 3,743 known comets in the Solar System.
87. A meteoroid is a small space rock; a meteor is a meteoroid that enters Earth’s atmosphere and burns up; a meteorite is one that reaches the ground.
88. A meteor shower occurs when Earth passes through the trail of dust and debris left by a comet.
89. The largest known asteroid, Vesta, is about 530 kilometres in diameter.
90. Comets from the outer Solar System can take thousands of years to complete a single orbit of the Sun.

Space Travel and Exploration (Facts 91–101)

Space exploration has answered thousands of questions about the Solar System and raised thousands more. The UK plays an active role through the European Space Agency and the UK Space Agency, and British scientists have contributed to many major missions.

91. The Space Age began in 1957 when the Soviet Union launched Sputnik 1, the first artificial satellite.
92. Neil Armstrong became the first human to walk on the Moon on 20 July 1969.
93. Tim Peake became the first British ESA astronaut to visit the International Space Station in December 2015.
94. The International Space Station orbits Earth at approximately 408 kilometres altitude, travelling at 27,600 km/h.
95. NASA’s Voyager 1 spacecraft, launched in 1977, is the most distant human-made object and has now left the Solar System.
96. The Mars rovers Curiosity and Perseverance have confirmed that liquid water once flowed on the Martian surface.
97. The James Webb Space Telescope, launched in December 2021, is the most powerful space telescope ever built.
98. The European Space Agency’s Rosetta mission landed a probe on a comet for the first time in 2014.
99. NASA’s New Horizons spacecraft flew past Pluto in 2015, sending back the first detailed images of the dwarf planet.
100. The UK Space Agency was established in 2010 and supports British contributions to space science, technology and exploration.
101. SpaceX’s Falcon 9 rocket was the first orbital-class rocket to land and be reused, transforming the economics of space launch.

The Fruit Solar System: A Scale Model for the Classroom

Scale models help children understand the vast distances and size differences between Solar System objects. If the Sun were a yoga ball 65 centimetres across, here is what everything else would look like.

Object	Fruit/Object Equivalent	Fun Scale Fact
Sun	Yoga ball (65cm)	The Sun contains 99.8% of all the mass in the Solar System
Jupiter	Football (22cm)	Jupiter is so big that all other planets could fit inside it
Saturn	Orange (7cm)	Saturn’s rings stretch up to 282,000 km but are only 1 km thick
Uranus	Golf ball (4.3cm)	Uranus rolls around the Sun on its side, tilted at 98 degrees
Neptune	Marble (3.9cm)	Neptune’s winds reach 2,100 km/h, the fastest in the Solar System
Earth	Cherry tomato (1.3cm)	Earth is the only planet known to support life
Venus	Cherry tomato (1.2cm)	Venus spins backwards compared with most other planets
Mars	Pea (0.7cm)	Mars hosts Olympus Mons, the tallest volcano in the Solar System
Mercury	Peppercorn (0.5cm)	Mercury is the fastest planet, completing one orbit in 88 days

Classroom activity: gather the items in the second column and arrange them across a school field to show relative distances. This practical task directly supports the Year 5 Science objective on the relative sizes of the Sun, Earth and Moon.

UK National Curriculum: Year 5 Earth and Space

Solar System content appears in the UK National Curriculum Science programme of study for Year 5, under the topic “Earth and Space.” The statutory requirements ask 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, as well as the apparent movement of the Sun across the sky.

A common misconception at this stage is believing that the Earth’s distance from the Sun causes the seasons. In fact, the seasons are caused by Earth’s axial tilt. When the Northern Hemisphere tilts towards the Sun, it receives more direct sunlight and experiences summer. When it tilts away, the light is spread over a larger area, and we experience winter.

The historical shift from a geocentric model (Earth at the centre of the universe) to the heliocentric model (Sun at the centre of the Solar System) is also part of the Year 5 curriculum. Nicolaus Copernicus proposed the heliocentric model in 1543, and Galileo Galilei provided observational evidence to support it. Teaching this shift in scientific thinking helps children understand how scientific knowledge develops and changes over time.

How to Remember the Planets: Mnemonics for Kids

The classic mnemonic for remembering the eight planets in order from the Sun is:

My Very Enthusiastic Mother Just Served Us Nachos

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

The original version included Pluto at the end (“Noodles”), but since its reclassification in 2006, the “Nachos” version has become standard in UK primary classrooms.

“Memory hooks like planet mnemonics do something worksheets often cannot: they give children a way back into a topic when they’re stuck. A pupil who blanks on a test but remembers ‘My Very Enthusiastic Mother’ can rebuild from there. That’s a genuine learning tool, not a shortcut.” Michelle Connolly, Founder of LearningMole and former teacher with over 15 years of classroom experience

Classroom activity: invite children to create their own planet mnemonic using a sentence where each first letter matches the planet sequence. Share and compare sentences as a class and discuss which ones are easiest to remember and why. This takes about ten minutes and produces a memorable, pupil-owned version of the fact.

UK-specific alternative: some teachers use “My Violent Earthworm Marched Joyfully Straight Up the Narrow path” to create a more vivid image for younger pupils. The slight absurdity helps retention.

Teaching Resources and Support

LearningMole provides curriculum-aligned video resources and teaching materials that bring Solar System topics to life for primary-aged children. Whether you are a teacher planning a Year 5 Earth and Space unit or a parent supporting space homework, LearningMole’s educational content covers the key concepts in accessible, child-friendly language aligned to the UK National Curriculum.

The space video resources explain planetary science through visual demonstration, making it easier for children to grasp the scale and movement of objects in the Solar System. Video-based learning is particularly effective for space topics because it can show what diagrams alone cannot: the relative sizes of planets, the motion of moons, and the appearance of planetary surfaces.

For parents supporting learning at home, LearningMole’s resources extend classroom content without requiring specialist knowledge. Simple home activities that complement the 101 facts in this guide include tracking the Moon’s phases over a four-week period, identifying visible planets in the evening sky using a free stargazing app, and building a scale model using the fruit equivalents in the table above.

Solar System Facts: Frequently Asked Questions

Conclusion

The Solar System is genuinely one of the most rewarding topics in the KS2 science curriculum, not because it is simple, but because children already arrive with questions about it. Curiosity about space tends to be self-sustaining: one fact leads to another question, which in turn leads to another fact. The 101 entries in this guide are a starting point, not a ceiling.

LearningMole’s space resources are designed for exactly this kind of learning: building a solid foundation of accurate, curriculum-aligned facts while leaving room for children to ask what comes next. Whether a pupil goes on to become fascinated by planetary geology, black holes or the possibility of life elsewhere in the universe, the Solar System knowledge in this guide gives them the context to make sense of whatever they discover later.

For teachers and parents, the practical activities here, the scale model, the mnemonic workshop and the Year 5 curriculum notes, are intended to make that curiosity easier to support. Space is enormous, but the entry points are small and accessible. Use the facts in this guide to open the door, then let the questions carry your learners the rest of the way.