You want to be a Space Millionaire?
Our solar system is a busy place! It's made up of a star (our Sun!), eight amazing planets, dwarf planets (like Pluto), moons, asteroids, comets, and lots of dust and gas. Everything in the solar system orbits, or travels around, the Sun.
Scientists believe our solar system formed from a giant, swirling cloud of gas and dust called a nebula. This is called the Nebular Hypothesis, and it happened about 4.6 billion years ago! Here's how it works:
1. The Cloud: A huge cloud of gas and dust (a nebula) existed in space.
2. Collapse: Something (like a nearby exploding star) caused the cloud to start collapsing and spinning.
3. The Sun Forms: Most of the material clumped together in the center, getting hotter and denser, eventually forming the Sun.
4. Planet Formation: Leftover gas and dust swirling around the Sun started to clump together, forming the planets, moons, and other objects.
Distance from Sun: ~0.39 AU
Size (compared to Earth): ~0.38 (Earth = 1)
Temperature: -173°C to 427°C (-280°F to 800°F)
Length of Day: ~59 Earth days
Length of Year: ~88 Earth days
Moons: None
Composition: Rocky
Interesting Fact 1: Mercury has wrinkles (called lobate scarps)!
Interesting Fact 2: A day on Mercury is longer than its year!
Exploration: Mariner 10, MESSENGER
Distance from Sun: ~0.72 AU
Size (compared to Earth): ~0.95
Temperature: ~464°C (867°F) - Hottest planet!
Length of Day: ~243 Earth days
Length of Year: ~225 Earth days
Moons: None
Composition: Rocky
Interesting Fact 1: Venus spins backwards (retrograde rotation)!
Interesting Fact 2: Venus has a very thick, toxic atmosphere.
Exploration: Venera probes, Magellan
Distance from Sun: 1 AU (by definition)
Size (compared to Earth): 1
Temperature: -88°C to 58°C (-126°F to 136°F) - Average ~15°C (59°F)
Length of Day: 24 hours
Length of Year: 365.25 days
Moons: One (the Moon!)
Composition: Rocky, with lots of liquid water
Interesting Fact 1: Only planet known to support life!
Interesting Fact 2: Earth's atmosphere protects us from harmful solar radiation.
Distance from Sun: ~1.52 AU
Size (compared to Earth): ~0.53
Temperature: -153°C to 20°C (-243°F to 68°F)
Length of Day: ~24.6 hours
Length of Year: ~687 Earth days
Moons: Two (Phobos and Deimos)
Composition: Rocky, covered in reddish iron oxide (rust)
Interesting Fact 1: Has the largest volcano in the solar system (Olympus Mons)!
Interesting Fact 2: Evidence suggests Mars once had liquid water.
Exploration: Many rovers and orbiters (e.g., Curiosity, Perseverance, Viking)
Distance from Sun: ~5.2 AU
Size (compared to Earth): ~11.2 (diameter)
Temperature: ~-145°C (-234°F) at cloud tops
Length of Day: ~9.9 hours
Length of Year: ~12 Earth years
Moons: 79+ (including Ganymede, the largest moon in the solar system)
Composition: Gas giant (mostly hydrogen and helium)
Interesting Fact 1: Has a giant storm called the Great Red Spot, larger than Earth!
Interesting Fact 2: Jupiter's strong magnetic field creates powerful auroras.
Exploration: Pioneer, Voyager, Galileo, Juno
Distance from Sun: ~9.5 AU
Size (compared to Earth): ~9.4 (diameter)
Temperature: ~-178°C (-288°F) at cloud tops
Length of Day: ~10.7 hours
Length of Year: ~29 Earth years
Moons: 82+ (including Titan, with its own atmosphere)
Composition: Gas giant (mostly hydrogen and helium)
Interesting Fact 1: Famous for its beautiful rings, made of ice particles!
Interesting Fact 2: Saturn is less dense than water - it could float in a giant bathtub!
Exploration: Pioneer 11, Voyager, Cassini-Huygens
Distance from Sun: ~19.2 AU
Size (compared to Earth): ~4.0 (diameter)
Temperature: ~-224°C (-371°F)
Length of Day: ~17.2 hours
Length of Year: ~84 Earth years
Moons: 27+
Composition: Ice giant (water, methane, ammonia)
Interesting Fact 1: Uranus rotates on its side (its axis is tilted almost 98 degrees)!
Interesting Fact 2: Uranus has faint rings.
Exploration: Voyager 2
Distance from Sun: ~30.1 AU
Size (compared to Earth): ~3.9 (diameter)
Temperature: ~-214°C (-353°F)
Length of Day: ~16.1 hours
Length of Year: ~165 Earth years
Moons: 14+ (including Triton, which orbits backwards)
Composition: Ice giant (water, methane, ammonia)
Interesting Fact 1: Neptune has the strongest winds in the solar system!
Interesting Fact 2: Neptune was discovered using mathematical predictions.
Exploration: Voyager 2