Science pack for subs

Everything around you is made of matter. Matter is anything that takes up space and has mass. It comes in three main forms: solid, liquid, and gas.

A solid keeps its own shape. A rock, a pencil, and an ice cube are solids. You can pick them up, and they do not change shape.

A liquid has no shape of its own. It takes the shape of whatever holds it. Water poured into a cup looks like the cup. Pour it into a bowl, and it looks like the bowl.

A gas has no shape either, and it spreads out to fill any space. The air in a balloon is a gas. It fills the whole balloon.

Water can be all three. When it gets cold enough, it freezes into ice, which is a solid. When it gets hot enough, it boils and turns into water vapor, which is a gas.

When you flip a switch, a light comes on. But the electricity did not start in the wall. It began at a power plant, sometimes many miles away.

At most power plants, a machine called a turbine spins. The spinning turbine turns a generator, which makes electricity. Some plants use heat to make steam that spins the turbine. Others use falling water or wind.

Electricity leaves the plant through thick wires. Tall towers hold the wires high above the ground, and the electricity travels long distances over these power lines.

Near your home, a device called a transformer changes the electricity so it is safe to use. Then smaller wires carry it to houses, schools, and stores. Inside the walls, wires reach every outlet and light.

Electricity flows only along a loop, called a circuit. When you switch on a lamp, you close the circuit, and the electricity can flow through the bulb. When you switch it off, the circuit opens and the flow stops.

Jupiter is the biggest planet in our solar system. It is so big that all the other planets could fit inside it with room to spare. More than 1,300 Earths could fit inside Jupiter.

Unlike Earth, Jupiter is not a rocky planet. It is a gas giant, made mostly of hydrogen and helium, the same gases that make up the sun. If you tried to land a spaceship on Jupiter, you would find no solid ground to stand on. You would sink deeper and deeper through thick, swirling clouds.

Those clouds make colorful stripes across the planet. Jupiter also has a giant storm called the Great Red Spot. This storm is wider than Earth and has been watched by astronomers for almost two hundred years. Scientists have noticed that the Spot has been getting smaller over time.

Even though Jupiter is huge, it spins faster than any other planet. One day on Jupiter lasts only about ten hours. The planet also has almost a hundred known moons. In 1610, an astronomer named Galileo used one of the first telescopes to discover four of the largest ones. They are still called the Galilean moons.

Several spacecraft have visited Jupiter. Some flew past it, and some, like the Juno mission, have orbited the planet to study its clouds, its storms, and what lies deep inside.