One ordinary star, eight worlds, and a great deal of beautiful emptiness
About 4.6 billion years ago a cloud of gas and dust collapsed. Most of it became the Sun; the leftover crumbs became the planets, moons, asteroids and comets. Tap any world in the model to open its story.
The Sun holds 99.86% of all the mass in the solar system. Everything else — all eight planets, every moon and asteroid — is built from the last 0.14% of leftovers.
Mercury, Venus, Earth and Mars are small, dense and rocky — close enough to the Sun that ice and gas were mostly cooked away, leaving stone and metal.
Jupiter, Saturn, Uranus and Neptune are huge balls of gas and ice. Jupiter alone is more massive than all the other planets combined, twice over.
Nothing is powered. Every world simply falls around the Sun forever, its sideways speed exactly balancing the Sun's gravity — Newton's insight, and Kepler's ellipses.
Press True scale on the model to spread the planets to their real relative distances — and watch them shrink to specks in an ocean of black.
Sunlight takes 8 minutes to reach Earth — and over 4 hours to crawl out to Neptune. The Sun you see already left 8 minutes ago.
...the Sun would be a beach ball 26 metres away, and Neptune a pinhead a full kilometre out. The planets are tiny; the gaps are everything.
Voyager 1, launched 1977 and still flying, is the most distant human-made object — yet it has barely begun to leave the Sun's influence.
Earth sits in the narrow "habitable zone" where water stays liquid. A little closer and we'd be Venus; a little farther, Mars. Our whole existence is a matter of orbital real estate.
The day (Earth's spin), the month (the Moon), the year (our orbit) and the seasons (our tilt) are all clocks written in the sky — the origin of every calendar humanity has kept.
Jupiter's immense gravity flings away or swallows many comets that might otherwise strike Earth. The giant is, in part, our bodyguard.
The Moon, Mars and the asteroids hold water and metals. Understanding these orbits is the first step to becoming a species that lives on more than one world.
Indian astronomy (Jyotiṣa) watched the sky with extraordinary care and named nine grahas — "seizers", the moving lights that travel against the fixed stars. Toggle Graha names on the model to see them. Offered here as the sky-lore it is, alongside the modern map.
In good faith: the Navagraha are the observed moving bodies of a sky-watching, geocentric tradition — the Sun and Moon are counted as grahas, Earth is not, and Rāhu and Ketu are the two points where the Moon's path crosses the Sun's (the eclipse nodes), not physical planets. This is a different, older frame than the heliocentric one the 3D model shows. The astronomy behind Jyotiṣa was genuinely sophisticated — tracking periods and eclipses to remarkable precision — and it is distinct from the astrological meanings later layered onto the grahas. Both deserve to be seen clearly, and separately.
For most of history, the sky was assumed to circle us. Undoing that assumption was one of the hardest, most dangerous ideas humans ever had.
In the Āryabhaṭīya, Āryabhaṭa argues the apparent daily motion of the stars is caused by the Earth rotating on its axis — not the heavens turning around us. He computes planetary periods and eclipse causes with startling accuracy, centuries ahead of Europe.
Ptolemy's Earth-centred system, with its wheels-within-wheels (epicycles), predicted the sky well enough to reign unchallenged in the West for 1,400 years.
On his deathbed, Nicolaus Copernicus publishes the heliocentric model — the Earth is just another planet. It is elegant, and it is heresy.
Using Tycho Brahe's data, Johannes Kepler discovers the planets move in ellipses, not perfect circles, sweeping equal areas in equal times. The real shape of the orbits, at last.
Galileo sees four moons circling Jupiter and the phases of Venus — direct proof that not everything orbits Earth. He spends his last years under house arrest for saying so.
Isaac Newton shows one law of gravity governs both the falling apple and the orbiting Moon — binding the entire solar system into a single, predictable clockwork.
Wobbles in Uranus's orbit let Le Verrier calculate where an unseen planet must be. Astronomers pointed a telescope at the spot that night — and there was Neptune, exactly as predicted.
Earths would fit inside the Sun. And the Sun is a completely average star — there are far larger ones.
Venus is hotter than Mercury despite being farther from the Sun — a runaway greenhouse of thick CO₂ traps the heat. Its surface would melt lead.
Venus spins so slowly that a single day there lasts longer than its entire year — and it spins backwards compared to the others.
Jupiter's Great Red Spot is a storm wider than Earth that has been raging for at least four centuries, maybe far longer.
Saturn's rings stretch ~280,000 km wide but are often only about ten metres thick — a sheet of ice and rock thinner than a house is tall.
If you shrank the Sun to a marble, the nearest other star would still be about 500 km away. Between the stars is almost pure emptiness.