Cosmic Glossary
Demystifying the language of the stars.
Asteroid
An asteroid is a small rocky body orbiting the Sun, mostly found in the asteroid belt between Mars and Jupiter. They are remnants from the early solar system that never formed into planets....
Big Bang
The Big Bang is the scientific theory that describes the origin of the universe approximately 13.8 billion years ago, when all matter and energy were concentrated in an extremely hot, dense state....
Black Hole
A black hole is a region of spacetime where gravity is so strong that nothing, not even light, can escape from it. They form when massive stars collapse at the end of their life cycles....
Comet
A comet is a small icy body that orbits the Sun and develops a coma and tail when it approaches the Sun. Comets are composed of ice, dust, and rocky material....
Cosmic Microwave Background
The Cosmic Microwave Background (CMB) is the thermal radiation left over from the Big Bang, filling the universe and providing a snapshot of the infant universe when it was just 380,000 years old....
Dark Energy
Dark energy is a mysterious force that is causing the expansion of the universe to accelerate. It makes up about 68% of the universe's total energy content....
Dark Matter
Dark matter is invisible matter that does not emit, absorb, or reflect light, but can be detected through its gravitational effects on visible matter and cosmic structures....
Exoplanet
An exoplanet, or extrasolar planet, is a planet that orbits a star outside our solar system. Since the first confirmed detection in the 1990s, thousands of exoplanets have been discovered, revolutioni...
Galaxy
A galaxy is a massive system of stars, gas, dust, and dark matter bound together by gravity. Galaxies are the fundamental building blocks of the universe, containing anywhere from millions to trillion...
Meteor
A meteor is the streak of light produced when a meteoroid enters Earth's atmosphere and burns up. Commonly known as a 'shooting star,' meteors are not stars but small particles from space....
Nebula
A nebula is a giant cloud of dust and gas in space, often spanning hundreds of light-years across. These cosmic clouds are among the most beautiful and important objects in the universe, serving as bo...
Neutron Star
A neutron star is the extremely dense remnant of a massive star after a supernova explosion. It contains more mass than our Sun packed into a sphere about 20 kilometers across....
Pulsar
A pulsar is a rapidly rotating neutron star that emits beams of electromagnetic radiation, appearing to 'pulse' as it rotates like a cosmic lighthouse....
Quasar
A quasar is an extremely luminous active galactic nucleus powered by a supermassive black hole at the center of a distant galaxy. These are among the most energetic and distant objects in the observab...
Supernova
A supernova is the explosive death of a massive star, one of the most energetic events in the universe. During this catastrophic explosion, a star can briefly outshine an entire galaxy, releasing as m...