Stars are massive, luminous spheres of hot gas—mainly hydrogen and helium—that shine due to nuclear fusion in their cores. Galaxies are vast collections of stars, gas, dust, and dark matter, bound together by gravity. Stars form in clouds of gas and dust called nebulae. Depending on their mass, they go through various stages: protostar → main sequence → red giant → white dwarf / neutron star / black hole.

• Spiral Galaxies: Like the Milky Way, with rotating arms of stars and gas.
• Elliptical Galaxies: More rounded and older, with less gas and star formation.
• Irregular Galaxies: Chaotic shapes, often the result of galactic collisions or gravity distortions.

Powerful telescopes like Hubble and JWST let astronomers observe distant galaxies, stellar nurseries, and supernova explosions—offering clues to the universe’s age and structure. The Milky Way is just one of over 2 trillion galaxies in the observable universe, and many of the stars you see at night are only a tiny fraction of those in our own galaxy.

Exploring stars and galaxies helps us understand not only how the universe formed, but also our cosmic origins and what lies beyond.