How it was made

It all runs on a clock

Every body in the viewer is placed from the date. Pick a moment and it works out where each planet is from VSOP87, the planetary theory Pierre Bretagnon and Gérard Francou published in 1988², and from 1800 to 2200 the planets land within 100,000 km of JPL Horizons^{3, 4}.

JPL's simpler fitted orbits, which stand in while the series loads, can be more than 8 million km out over the same years⁵.

The orrery behind these words runs that same series. Drag the date and the planets go where they really were, or will be, on that day. The distances are to scale and the dots aren't, since at this scale even Jupiter would be smaller than a pixel.

Pull out to Neptune and press Play, and each second is about two and a half years: the outer planets crawl while the inner ones blur round the Sun.

The Moon has a theory of its own, chapter 47 of Jean Meeus's Astronomical Algorithms⁶. Meeus gives its place in the frame of its own date, which turns about 0.4 degrees away from the planets' frame by 2027, enough to make the 2026 eclipse miss the Earth, so the viewer carries it across⁷.

The named moons fly orbits fitted to Horizons, fourteen numbers each, and every planet stands on its pole and turns on its prime meridian as the IAU's report gives them⁸, so Saturn's rings open and close as we see them from here³.

The Earth, one layer at a time

Start with a ball and a photograph. The day map is NASA's Blue Marble Next Generation for June 2004, made by Reto Stöckli from the MODIS cameras⁹, and the land's height comes from NOAA's ETOPO 2022¹⁰. On a plain lit ball, with nothing else on, this is all it is.

Each picture in this chapter is the same held frame of the viewer, 20 October 2026 at 17:00 UTC, with the layers above it switched off.

Then the sea gets a shader of its own. Its colour follows how deep the water is and how clear, from ETOPO's depths and MODIS-Aqua's measure of how fast light fades in the water, and the light fading down through it follows Morel and Maritorena's measurements^{11, 12}.

The bright patch is the Sun's glint, spread over wind-ruffled waves the way Cox and Munk measured it from photographs of the Sun's glitter on the sea¹³.

The clouds are NASA's own, the Blue Marble's cloud layer from MODIS on the Terra satellite, built from its full 43,200 by 21,600 pixel original^{14, 1}.

Then the air, a shell drawn with Rayleigh and Mie scattering after Sean O'Neil's chapter in GPU Gems 2^{15, 16}. It's what tints the limb blue and softens the edge of the day.

Last, the night. Past the terminator the cities come on from NASA's Black Marble, the Earth's lights in 2016 as the VIIRS camera on Suomi NPP saw them¹⁷.

Then it was checked against the real thing. NASA's EPIC camera photographs the whole sunlit Earth from deep space¹⁸, and on six of its frames from 2024 to 2026 the viewer's clear ocean came out at 0.94 of EPIC's brightness, the Sahara at 1.05 and the Amazon at 0.95.

The colours were fitted to EPIC to begin with, so this shows how well the fit holds, and the accuracy page says as much¹⁹.

Down to the ground

Fly in and the globe hands over to imagery streamed as you go. Down to about 31 metres a pixel it's NASA's, the Landsat WELD composite of 1999 served through NASA's GIBS^{20, 21}.

1,400 km above Egypt, 20 October 2026 at 09:30 UTC.

The coarse levels ship with the site and the finer ones stream straight from NASA as you close in, so the delta sharpens as you drop through it²¹.

160 km above the Nile delta.

Go lower still and the viewer switches to Sentinel-2 cloudless by EOX, about 15 metres a pixel, colour-matched to the Landsat above it^{22, 21}. These pictures stop a level short of that, so everything in them is NASA's.

38 km above Giza.

The Sun, up close

From far off the Sun is too bright to look at, so it's drawn as a lens would see it, with a core that always clips white, a soft halo, twenty diffraction rays and a fan of fine strands after the glare in the human eye that Ritschel and colleagues simulated in 2009^{23, 24}.

Come close and it has a surface. Its granules are cells about 1,200 km across that are born, swell and die on a clock running ten times fast, and the whole disc darkens towards its edge by the law Neckel and Labs measured^{23, 25}.

The sunspots follow the date, their number and latitude from the solar cycle, each group tilted by Joy's law²⁶.

This is the Detailed style, in colour. The viewer opens on the Realistic style, which keeps the Sun white.

On the limb, prominences are volumes of glowing hydrogen, ray marched as curtains, loops and twisted arches, and one of the arches erupts every five minutes²³.

The Realistic style, 1.9 solar radii from the Sun's centre.

The sky behind it all

The stars you can pick out are real ones, from the HYG catalogue down to magnitude 8 and Tycho-2 from there to 10^{27, 28}, and behind them is the glow of the faint ones from NASA's Deep Star Maps, made from ESA's Gaia²⁹. They're all drawn at one exposure, with no diffraction spikes, and every one is placed through the same sky frame³⁰.

Towards the centre of the galaxy, 20 June 2026.

The asteroid belt is 164,776 real asteroids from JPL's orbital elements, each solved on its own orbit for the date on the graphics card, so the Kirkwood gaps, the Hildas' triangle and Jupiter's Trojans are the data's own^{31, 30}.

They shine at their true brightness by default, which is faint, and this picture turns on the switch that lights them by size.

From your street to the edge

The zoom out is one unbroken pull back from 8 km above home to the microwave background, about two minutes at a nearly even pace^{32, 33}.

The planets are moved onto the camera's line so you pass them, and the flight says so while it does.

Pictures from the flight, rendered for the universe page.

Past the Milky Way come 44,228 named galaxies from catalogues such as HyperLEDA, each at its own distance with its own type, size and tilt^{34, 32}.

Then 584,449 real galaxies from the Sloan Digital Sky Survey as Tempel and colleagues grouped them³⁵, and past what the surveys have mapped, 1.5 million more from our own simulation of dark matter under its own gravity, run with the FastPM method on Planck's 2018 cosmology^{36, 37, 32}.

Black holes, traced ray by ray

On the black holes page every pixel's light is followed backwards through the curved spacetime round the hole, stepped with RK4 in units of its own radius^{38, 39}. The disk is a thin Shakura-Sunyaev disk⁴⁰, each patch drawn as a blackbody at its temperature and shifted by its speed and by gravity, which is why one side burns brighter.

Near the shadow's edge each pixel traces five rays, so the thin ring of light that has looped round the hole stays a ring. Blurred to the Event Horizon Telescope's resolution, the model's ring comes out within 3% of the size of the one in the 2019 picture of M87*^{38, 41}.

The sky behind is NASA's Deep Star Maps again.

A rocket game on the same Earth

Qmax, the rocketry game, flies on the same planet the viewer draws, 6,371 km in radius with about 9.4 km/s needed to reach orbit^{42, 43, 44}. Round the ship is a true-scale scene in metres whose origin moves with it, so the numbers stay precise however far you fly.

Flight is integrated with RK4, a coasting craft goes on rails along its Kepler orbit while the map predicts its path in patched conics, and each engine's plume is a volume ray marched by its propellant, with Mach diamonds⁴³.

On the Moon the ground comes from NASA's laser altimeter⁴⁵, and the Prospector rover rolls off the Wayfarer lander's deck, laying tracks and throwing dust into the vacuum⁴³.