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The WhyCosmos Space Glossary

Space, defined for curious kids.

By the WhyCosmos team · Last updated:

This glossary explains the words your child brings home from the sky — in plain language, at two levels: one for an 8-year-old, one for a 13-year-old. Every entry is written by the team behind India’s live astronomy classes for ages 8–16, and comes with facts, dates and sources you can check.

Each entry answers the question the way you would want it answered at your dinner table: a straight definition first, then how to explain it to your child, key facts, and the questions parents and kids actually ask.

See all 25 Space Terms for Kids →
Space agencies

ISRO

ISRO (Indian Space Research Organisation) is India's national space agency, founded on 15 August 1969 and headquartered in Bengaluru.

Space agencies

NASA

NASA (National Aeronautics and Space Administration) is the United States' space agency, founded in 1958.

Missions

Chandrayaan-3

Chandrayaan-3 is ISRO's third Moon mission, which made India the first country to land near the Moon's south pole, on 23 August 2023.

Events

National Space Day

National Space Day is India's annual space celebration on 23 August, marking the anniversary of Chandrayaan-3's historic Moon landing.

Instruments

Telescope

A telescope is an instrument that collects light with a lens or mirror to make distant objects appear brighter, sharper and closer.

Tools & software

Stellarium

Stellarium is free, open-source planetarium software that displays a realistic, real-time night sky from any location on Earth, at any date and time.

Rockets

Space Launch System (SLS)

The Space Launch System (SLS) is NASA's super heavy-lift rocket, built to carry the Orion spacecraft and astronauts to the Moon under the Artemis programme.

Objects in space

Black Hole

A black hole is a region of space where matter is squeezed so tightly that gravity becomes strong enough to trap everything, including light.

Competitions

Astronomy Olympiad

The Astronomy Olympiad in India is a multi-stage competition for school students: the National Standard Examination in Astronomy (NSEA), the Indian National Astronomy Olympiad (INAO), a selection camp, and finally the International Olympiad on Astronomy and Astrophysics (IOAA), where five students represent India.

Concepts

Astronomy vs Astrology

Astronomy is the scientific study of stars, planets, galaxies and the universe, based on observation, mathematics and testable predictions.

Your child asks questions like this every week.WhyCosmos runs live online astronomy classes for ages 8–16, taught by real astrophysicists — where questions like these are the curriculum.