Space, or the “cosmos,” refers to the entire expanse that includes everything known and unknown in the universe—from planets and stars to galaxies, energy, time, and even invisible matter. Space is where Earth and everything we know exists, and it has no imaginable boundary.

Stars are massive, luminous objects in space made primarily of extremely hot gases, especially hydrogen and helium. Through nuclear reactions in their cores, they produce enormous energy that radiates outward as light and heat.

A solar system is a collection of celestial bodies that orbit a central star—such as the Sun—under the influence of gravity.

A black hole is one of the most fascinating and mysterious phenomena in the universe. It is a region of spacetime where gravity is so strong that nothing—not even light—can escape.