Solar System Concepts and Conversions

A unit of measurement used to express distances between stars. One light-year is the distance light travels in one year.

A unit of measurement used to express distances within our solar system. One AU is the average distance between the Earth and the Sun.

A large cloud of gas and dust in space. It is the birthplace of stars.

A very young star that is still forming. It is not yet hot enough to produce its own light.

The process in which hydrogen atoms fuse together to form helium, releasing massive amounts of energy.

A star that is stable and burning hydrogen fuel in its core. Most stars spend the majority of their lives in this stage.

A small, dense, and very hot remnant of a star that has exhausted its nuclear fuel. It is no longer able to produce energy by fusion.

A hypothetical object that is the end-stage of a white dwarf. It is predicted to be cold and dark.

A giant explosion that occurs at the end of a star's life. It releases a tremendous amount of energy and produces heavy elements.

A star that is much larger and brighter than our Sun. It is likely to end its life as a supernova.

A star that has expanded in size and cooled down at the end of its life. It is much larger and cooler than a main sequence star.

A region of space where the gravity is so strong that nothing, not even light, can escape.

The theory that the universe began as a singularity from which all matter and energy expanded and continues to expand.

A model of the solar system where the Earth is the center and the Sun and other planets revolve around it.

A model of the solar system where the Sun is the center and the Earth and other planets revolve around it.

A celestial object that orbits a star. It is large enough to have cleared its neighborhood of other objects.

A celestial object that orbits a star. It is similar to a planet but is smaller and has not cleared its neighborhood of other objects.

A small, rocky body that orbits the Sun. Most asteroids are found in the asteroid belt between Mars and Jupiter.

A region in the outer solar system beyond Neptune. It is home to many icy bodies, including dwarf planets like Pluto and Eris.

A region of icy bodies that surrounds the solar system. It is thought to be the origin of many comets.

A region between Mars and Jupiter where most of the solar system's asteroids are found.

A small body of ice and dust that orbits the Sun. When a comet passes close to the Sun, it heats up and releases gas and dust, creating its characteristic tail.

A small, rocky body that originates in space. When it enters Earth's atmosphere, it burns up and creates a streak of light called a meteor.

A streak of light produced when a meteoroid burns up in Earth's atmosphere.

A meteoroid that survives its journey through the atmosphere and reaches Earth's surface.

A planet that orbits a star outside of our solar system.

A natural object that orbits a planet. Our Moon is Earth's natural satellite.

An object that orbits a planet. It is built by humans and sent into space with a specific purpose.

A darkening of the Moon caused by the Earth blocking the Sun’s light.

A darkening of the Sun caused by the Moon blocking the Sun’s light.

The darkest part of a shadow. This area is where the light source is fully blocked.

The lighter part of a shadow. In this area, the light source is partially blocked.

The path on Earth where a total solar eclipse is visible.