This is the whole WhyCosmos Space Glossary on one page. The first ten words get a full explainer of their own — tap any of them for the complete entry, including how to explain it to an 8-year-old and to a 13-year-old. The remaining fifteen are quick definitions you can read out at the dinner table tonight. Children do not learn space in a syllabus order — they learn it in the order the questions arrive, and this list is built for that: no prerequisites, no jargon, and no pretending a word is simple when it is not.
How to use this list with your child
India's own space agency — and the reason your child's first rocket hero is Indian.
India's national space agency, founded on 15 August 1969 and headquartered in Bengaluru.
Founded 15 Aug 1969 · landed near the Moon's south pole in 2023Read the full ISRO explainer →The agency that put humans on the Moon, and just flew a crew around it again.
The United States' space agency, founded in 1958, now flying astronauts around the Moon again.
Founded 1958 · Apollo 11, Mars rovers, James Webb Space TelescopeRead the full NASA explainer →The night India landed where no country had landed before.
ISRO's Moon mission that landed India near the lunar south pole on 23 August 2023.
23 Aug 2023 · Vikram lander and Pragyan rover · near the lunar south poleRead the full Chandrayaan-3 explainer →India's yearly permission slip to be obsessed with space — 23 August.
India's annual space celebration on 23 August, marking Chandrayaan-3's landing.
First held 2024 · marks the Chandrayaan-3 landing · schools nationwideRead the full National Space Day explainer →Not a magnifier. A light bucket — and the number on the box is the wrong number.
An instrument that collects light with a lens or mirror to make distant objects easier to see.
Aperture beats magnification · Galileo first turned one skyward in 1609Read the full Telescope explainer →The free app that turns 'what is that bright dot?' into an answer in ten seconds.
Free, open-source software that shows the real night sky from your exact location, live.
Free and open-source · works in a browser · no telescope neededRead the full Stellarium explainer →NASA's Moon rocket, and the answer to every child's 'which is the biggest?'
NASA's giant Moon rocket, built to launch astronauts toward the Moon under Artemis.
~98 m tall · carried astronauts around the Moon, April 2026Read the full Space Launch System (SLS) explainer →The object children ask about most — and secretly worry about at bedtime.
A region of space with gravity so strong that not even light can escape it.
Nothing escapes past the event horizon · first photographed April 2019Read the full Black Hole explainer →The academic summit of a space-obsessed childhood, explained without the hype.
India's staged astronomy competition, from a school screening exam to representing India at IOAA.
NSEA → INAO → selection camp → IOAA · India is consistently among the bestRead the full Astronomy Olympiad explainer →Two words, one letter apart, and the difference every curious family should know.
Astronomy is the science of the sky; astrology is a belief tradition about what it means for you.
One is a science with testable predictions · the other is a belief traditionRead the full Astronomy vs Astrology explainer →The curved path one object takes around another under gravity — the Moon around Earth, Earth around the Sun. Objects in orbit are constantly falling, but moving sideways fast enough to keep missing.
Any object that orbits a bigger one. The Moon is Earth's natural satellite; the machines ISRO launches for weather, TV and navigation are artificial satellites.
A vast collection of stars, gas and dust bound together by gravity. Ours is the Milky Way, home to a few hundred billion stars.
The distance light travels in one year — about 9.5 trillion kilometres. It measures distance, not time, which trips up most adults too.
The Sun and everything gravitationally bound to it: eight planets, their moons, dwarf planets like Pluto, plus asteroids and comets.
A pattern of stars people named long ago, like Orion. The stars in one are usually nowhere near each other in space — only in our line of sight.
When one body passes into another's shadow or blocks its light. A solar eclipse is the Moon hiding the Sun; a lunar eclipse is Earth's shadow falling on the Moon.
The attraction between anything with mass. It keeps your feet on the ground, the Moon in orbit, and turns collapsing stars into black holes.
A meteor is the streak of light when a space rock burns in our atmosphere — a shooting star. If a piece survives and lands, it is a meteorite.
A ball of ice, dust and rock that grows a glowing tail when it nears the Sun and its ice turns to gas.
A rocky leftover from the solar system’s formation. Most orbit the Sun in a belt between Mars and Jupiter.
A cloud of gas and dust in space — some are the nurseries where new stars are born, others the debris of stars that died.
The explosion of a massive star at the end of its life, briefly outshining an entire galaxy and scattering the elements we are made of.
A robotic vehicle that drives on another world's surface. Pragyan drove on the Moon; Perseverance is driving on Mars right now.
A person trained to travel into space. India’s word for its own is gaganyatri, from the Gaganyaan human spaceflight programme.
Start with the words they can see or hear about: Moon, orbit, planet, star, satellite and gravity. Then add the ones from the news they will hear anyway — ISRO, NASA, Chandrayaan-3 and black holes.
Use things they can hold or see. A ball and a torch explain day and night; a ball on a string explains orbits. Every full entry in this glossary includes a version written for an 8-year-old and one for a 13-year-old.
Astronomy is the science of what stars and planets are and how they work, tested by observation and mathematics. Astrology is a belief tradition about what those positions mean for human lives; it does not make testable predictions.
No. The naked eye, a free sky app such as Stellarium, and a curious adult are the real starter kit. A telescope is better bought after a few months of genuine interest, when it becomes a reward rather than a frustration.
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.
