Earth's got a lot of water! About 1.4 billion cubic kilometers of it, and 98.3% is liquid. So where did it all come from? Imagine a pot of water boiling away - that's what Earth's surface would have been like when it formed. So, the water had to come later. But how? Let's explore!

One theory is that Earth ordered water from an "asteroid delivery service"! Sounds crazy, right? Well, not really. The idea is that colliding asteroids brought water to Earth. Today, large asteroids hit Earth only once every 20 million years. Not enough to bring all that water, you think? True, but when Earth was a baby planet, these collisions were like a weekend asteroid party! More frequent, and asteroids had more water back then.

You might wonder why asteroids lost almost all of their water. It's the Sun's fault! The Sun's heat evaporated the water, and weak gravity couldn't hold it. It's like leaving a water bottle in the sun, but on a cosmic scale.

• Earth's Perfect Spot in the Solar System: Earth's distance from the Sun keeps things cool enough so the water doesn’t boil. It's like Goldilocks - not too hot, not too cold. Liquid water sticks together because of hydrogen bonding - a unique connection between water molecules.

• Earth's Gravity Holds It Tight: Earth's gravity is like a big hug for water, holding oceans and even gases within the atmosphere. Some gases may escape, but water vapor stays with us. It's like putting a lid on a pot to keep the steam in!