Vocabulary
Accretion
Accretion is the process where small pieces of dust and rock in space stick together over time to form larger objects, like planets. For example, tiny dust particles in the early Solar System gradually came together through accretion to eventually become Earth and the other planets.
Element
An element is a substance made of only one type of atom, such as hydrogen, helium, or oxygen. For example, hydrogen and helium are the most common elements in the universe and played a big part in forming the stars and planets.
Gravity
Gravity is the force that pulls objects toward each other. It keeps planets in orbit around the Sun and helps clumps of dust come together to form planets. For example, Earth's gravity keeps you firmly on the ground and also keeps the Moon circling around our planet.
Orbit
An orbit is the path one object takes as it moves around another object in space. For example, Earth moves in an orbit around the Sun, completing one full circle each year.
Solar System
The Solar System is the group of planets, moons, asteroids, and other objects that orbit our Sun. For example, our Solar System includes Earth, Mars, Jupiter, the Sun, and many other objects.