The Rocky Worlds

Key facts

Mercury

Mercury is the smallest planet and the closest to the Sun. With almost no air to hold heat, its days are hot enough to melt lead and its nights are colder than Antarctica.

Venus

Venus is almost Earth’s twin in size, but it is a nightmare world: its thick carbon-dioxide air traps heat so well that it is the hottest planet, and its clouds are made of sulfuric acid. It also spins backwards compared to most planets.

Mars

Mars is a cold desert world, red because its dust is full of iron oxide (rust). It has the tallest volcano in the Solar System, ancient dry riverbeds, and ice at its poles. Billions of years ago it had lakes – maybe even life.

Quiz

1. Which planet is the hottest?

   • ☐ Mercury
   • ☐ Venus
   • ☐ Mars
   • ☐ Jupiter

2. What makes Mars red?

   • ☐ Lava
   • ☐ Rust (iron oxide)
   • ☐ Red plants
   • ☐ Reflected sunsets

3. What did the Ingenuity helicopter do on Mars in 2021?

   • ☐ Found water
   • ☐ First powered flight on another planet
   • ☐ Brought rocks home
   • ☐ Landed humans

Find it in the sky

Use the Sky Finder at seethestar.com. Tick what you find and write when you saw it.