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☀️ KNOW PRIMARY · AGES 6–11

PLANETS &
SPACE

☀️ The Extreme World Closest to Our Star! 🪐

📖 150 Topics 🆓 FREE + PRO ⏱️ 5 min per comic 🧠 Quiz included
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CLOSEST ORBIT
58 Million km
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EXTREME HEAT
430°C Day
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EXTREME COLD
-180°C Night
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NO AIR
Empty Vacuum
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CRATERED
Ancient Scars
☀️ MERCURY: CLOSEST TO THE SUN
TOPIC 03 · PLANETS & SPACE · 88 EARTH DAYS PER ORBIT
PAGE 1 OF 5 — THE CLOSEST WORLD
THE SCORCHED WORLD
Mercury: the closest planet to the Sun, a small rocky world with a heavily cratered surface
CLOSEST TO THE SUN!
Mercury is the closest planet to the Sun - only 58 million kilometers away. That's closer than any other planet! Because it's so close to the Sun's intense heat and radiation, Mercury is one of the most extreme places in our entire solar system. It orbits the Sun in just 88 Earth days!
⚡ DID YOU KNOW?
Mercury is NOT the hottest planet — Venus is! That's because Venus has a thick atmosphere that traps heat. Mercury has no atmosphere at all!
CLOSE!
FAST ORBIT
Mercury's fast orbit: 88 Earth days to circle the Sun at a speed of 47 km per second
⚡ 88 Earth days per orbit
💫 Speed: 47 km per second
SMALLEST TERRESTRIAL
Mercury size comparison: the smallest terrestrial planet, even tinier than Earth's Moon
🪨 Only 4,879 km diameter
⚪ Smaller than our Moon
PAGE 2 OF 5 — INSIDE MERCURY
INTERNAL STRUCTURE
Mercury's internal structure with its enormous iron core making up most of the planet's interior
IRON CORE WORLD
Despite being the smallest terrestrial planet, Mercury has an enormous iron core that makes up most of its interior. The core is so large that scientists are still puzzled by how it got there. Mercury's crust is thin and heavily cratered from billions of years of impacts.
IRON!
CRUST
Mercury's thin rocky crust riddled with craters from billions of years of impacts
🪨 Thin rocky shell
💥 Covered in craters
MANTLE
Mercury's rocky mantle layer sandwiched between the thin crust and the iron core
🌊 Rocky layer
🔥 Hot intermediate zone
IRON CORE
Mercury's enormous dense iron core that puzzles scientists with its unusual size
⭐ Enormous metal center
🔴 Extremely dense iron
PAGE 3 OF 5 — EXTREME TEMPERATURES
DAYTIME
Mercury's daytime surface baking at 430°C under intense solar radiation with no atmosphere
🔥 430°C surface
☀️ Extreme solar radiation
NIGHTTIME
Mercury's nighttime surface freezing at -180°C with nothing to hold the heat
❄️ -180°C surface
🌑 Deep freezing cold
TEMPERATURE EXTREMES
Mercury temperature extremes: 430°C in sunlight to -180°C in darkness, a 610-degree swing
THE BIGGEST SWING
Mercury has the biggest temperature difference of any planet! The side facing the Sun gets scorching hot at 430°C — hot enough to melt lead! But the side facing away from the Sun is frozen at -180°C. That's a swing of 610 degrees! This happens because Mercury has almost NO atmosphere to distribute heat.
EXTREME!
PAGE 4 OF 5 — CRATERED SURFACE
ANCIENT BOMBARDMENT
Mercury covered in ancient impact craters preserved for billions of years with no erosion
CRATER WORLD
Mercury's surface is covered with thousands of impact craters — some massive and some tiny. These craters are evidence of billions of years of asteroid and comet impacts. Unlike Earth, Mercury has no atmosphere and no plate tectonics to erase these ancient scars. Mercury looks a lot like our Moon!
BOOM!
CRATERS
Mercury's surface: thousands of impact craters preserved since the solar system's early days
💥 Thousands of impacts
⭕ Preserved forever
ESCARPMENTS
Huge cliff-like escarpments stretching hundreds of kilometres across Mercury
🏔️ Massive cliffs
📏 Hundreds of km long
PLAINS
Smooth volcanic plains on Mercury where ancient lava flows filled in some craters
🌍 Smooth regions
🪨 Ancient lava flows
PAGE 5 OF 5 — MOTION IN SPACE
CLOSEST ORBIT
Mercury's elliptical orbit around the Sun — the fastest planet at 47 km per second
FASTEST MESSENGER
Mercury is named after the Roman messenger god because it moves so fast across the sky! It orbits the Sun in just 88 Earth days — the fastest of all the planets. Mercury gets close to the Sun but never crashes into it because its elliptical orbit keeps it at a safe distance. It's also the closest planet to the Sun!
⚡ DID YOU KNOW?
A "day" on Mercury (one complete rotation) takes 59 Earth days. That means one Mercury day is longer than one Mercury year!
ZOOM!
ORBIT SPEED
Mercury orbital speed of 47 km per second making it the fastest planet in the solar system
⚡ 47 km per second
🏃 Fastest planet
KEY FACTS
Key Mercury facts: 58 million km from the Sun, 88-day year, temperatures from 430 to -180°C
📍 58 million km from Sun
⏱️ 88 Earth days per year
🌡️ 430°C to -180°C
☀️ QUIZ TIME!
MERCURY · 5 QUESTIONS
QUESTION 01
Is Mercury the hottest planet?
QUESTION 02
Why does Mercury have no atmosphere?
QUESTION 03
How long is a "year" on Mercury?
QUESTION 04
What's Mercury's daytime temperature?
QUESTION 05
Which planet is closest to the Sun?
0/5
QUESTIONS CORRECT
Keep learning about space!
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