Who it is for
Readers here are old enough to be insulted by being talked down to, and new enough to be lost by a research paper. Almost every decision on this site comes from trying to sit in that gap. We use the real numbers and the real images, then we take the time to explain them.
Everything is in English, French and Arabic, with full right-to-left layout. It works offline, installs from the browser like an app, and runs on the kind of hardware a school actually owns. Those are not items on a feature list. They decide who gets to use it.
Where it came from
OrbitLab began as an orbital-mechanics workspace: a research propagator with a form in front of it. That tool is still here, at the front of the site, and it still answers the question it was built for. The lessons came later, out of what people asked while using it. Not what the number says, but why the orbit does that at all.
Where the astronomy comes from
The photographs are from NASA, ESA, the Event Horizon Telescope and LIGO, credited file by file. Star positions come from the Hipparcos catalogue and the constellation figures from an openly licensed dataset. The Sun, Moon and planets are computed in your browser from published series rather than fetched from a service, which is why the sky map still works with no connection.
The interactive visuals are simplified illustrations, not exact simulations, and the pages carrying them say so. Where something is interpreted rather than measured, it is labelled and its source is named. If you find a mistake, tell us. We would rather be trusted than impressive.
How it is designed
The colours are a spectrum
Almost every nebula photograph you have seen is built from two emission lines: hydrogen-alpha at 656.3 nanometres, and doubly ionised oxygen at 500.7. Astrophotographers isolate them with narrowband filters, and that false-colour pairing is the visual language of the Hubble and Webb images on these pages. Those two lines are the two accents of this interface.
- Hydrogen-alpha 656.3 nm
- Doubly ionised oxygen 500.7 nm
One honest caveat, because it matters more than the story does. The hex values are not spectral conversions. Rendered literally, 656 nanometres is a dull dark red and 500.7 a saturated green, and as an interface pair they would fail contrast and look like a traffic light. The pairing comes from the physics. The exact tints are tuned to stay readable on a dark screen and on white paper.
Two colours, one rule
Rose carries action, and where you are: primary buttons, the active navigation item, the marker running down a lesson. Teal carries information: links, data readouts, related topics, anything you read rather than press. The contrast maths agrees with the rule. On a dark panel the teal measures 12.9:1 against the rose's 6.3:1, so small text belongs in teal anyway.
Arabic is not a translation layer
Arabic never receives letter-spacing here. It is a cursive script: the letters are drawn joined, and pulling them apart does not make a line feel airy, it makes the word look broken. Where a Latin reader gets a little extra room between letters, an Arabic reader gets word spacing and a taller line instead. The Arabic headline face descends from the same Kufic inscription tradition as the astrolabes and celestial globes in the Arab and Islamic astronomy path.
Structure carries information
The four destinations on the dashboard are not a grid. They are rungs on one logarithmic distance axis, each carrying the figure it stands for: eight light-minutes to the Sun, 4.2 light-years to the nearest star, 1,560 to the nearest black hole we know of, 2.5 million to Andromeda. The markers crowd toward the far end of the scale, and that crowding is the lesson.
- Solar System 8 light-minutes to the Sun
- Stars 4.2 light-years to the nearest star
- Black Holes 1,560 light-years to the nearest one we know of
- Galaxies 2.5 million light-years to Andromeda
Things we do not do
- We do not invent portraits for historical figures. No attested likeness of al-Sufi exists, so his profile carries an honest illustration and the alt text says so.
- We do not use colour as the only signal. Every state that matters carries an icon or a word as well.
- We do not simplify by removing the numbers. We simplify by explaining them.
- We do not animate for decoration. Motion shows depth, position or cause, and it stops completely for anyone who asks for less of it.
- We do not run advertising or third-party analytics, and nothing here is locked behind an account.
Questions and corrections
Mistakes in the astronomy, features that would help in a classroom, and contributions are all welcome.