whereintime.com
Time travel is easy. Landing is the hard part.
The Earth spins at 465 metres a second, orbits the Sun at 30 kilometres a second, and rides the Galaxy at 248. Jump through time without moving through space and the ground is not where you left it.
Slide the strip to pick when. Left is the past, right is the future, from the Earth's formation to the Sun's death.Tap a place. Latitude sets how fast the ground under you is moving.On the picture, choose what your machine holds still against: the ground, the Earth's centre, the Sun, the Solar System, the Galaxy or the universe. Nothing in the universe is at rest, so that choice is the whole game.
The picture is your real path, a corkscrew through space and time. Press ▶ under it, or drag the slider, to watch the Earth pull away.
Start Read the guide
Same physics. More drama. Pick a destination, pick a machine, hit the button, find out how you die.
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Guide
Landing windows
About
How to use it
When. Drag the strip or tap a preset. Left is the past, right is the future. The strip is logarithmic: an hour sits next to now, a year a third of the way out, the age of the Earth at the end.Where. Tap a place or use your location. Latitude sets how fast the ground under you is moving.What your machine holds still against. The six buttons on the picture. This is the whole game: nothing in the universe is at rest, so a machine that "stays put" has to stay put relative to something , and the something decides where you come out.
The six anchors
The ground. The machine is bolted to the crust, which is what every story machine quietly assumes. You land where you left. The only miss is the slow drift of the plate itself.The Earth's centre. Fixed to the Earth but not to its spin. The ground turns under you at 15° of longitude an hour, so a six-hour jump puts you a quarter of the way round the world, at the same latitude, at ground level. Over centuries the wobble of the axis moves the latitude too.The Sun. The Earth moves on round its orbit at 29.8 km/s: 30 km per second you skip, 2.6 million km per day. Only a whole number of sidereal years brings it back to the same place, and a calendar year is twenty minutes short of one.The Solar System. The same, plus the Sun's own loop around the centre of mass, about 12 m/s, mostly Jupiter's doing.The Galaxy. The Sun carries the whole Solar System round the Milky Way at about 248 km/s, once every 200 million years or so. That is 52 astronomical units a year. Three published values of the speed disagree, and the site shows all three.The universe. Against the afterglow of the Big Bang, the nearest thing there is to a universal rest frame, the Sun moves at 369.8 km/s toward the constellation Crater.
Reading the picture
Magenta is you , fixed at the point in space where you left. For the ground and the Earth's centre you see the globe: the dots are land, the pale lines are coasts, and the ground turns under you.
For the other four anchors you see your world line : where the point you are standing on actually goes. A jump of days shows the daily loop of the spin wound along the orbit. A few years show the orbit's turns wound along the Sun's track. Longer jumps show the whole track, with the orbit drawn as the tube it sweeps because the loops are too dense to draw.
At true proportions the loops would vanish: the orbit is 1 AU across and the Sun moves 52 AU a year. So widths are exaggerated and the caption says by how much. True scale , at the top right, removes every exaggeration.
Drag to turn, pinch or scroll to zoom. The animation replays whenever the jump changes.
Reading the numbers
Miss is the distance between you and the spot you left, at the moment you arrive. Under "Details" a small miss is split into up, east and north; a landing on the ground is given as a distance and bearing along the surface.The ground meets you is how fast the surface comes at you if you arrive at rest in that frame: 443 m/s at St. Croix for the Earth's centre, 29.5 km/s for the Sun. In Detailed you can instead keep your departure velocity, which is why a jump of whole sidereal days leaves almost no relative speed.± is one standard deviation from the models, never smaller than the measured error against JPL's ephemeris at that epoch.Tiers. model means a published model inside its tested range. projection means the model carried past it. statistical means the size is known but the phase is not. unknowable means past a validity wall, and the site says so rather than inventing a number. fiction is a story rule.
Landing windows
Hold still in a frame and wait: when does the Earth come back under you? For the Sun and the Solar System the site searches each sidereal anniversary for the Earth's closest pass and reports the miss, the exact moment, and how many seconds wide the window is. Most passes put the Earth's centre within its own radius of you, which means you come out inside the planet; a true landing within 100 km of the surface is rare, because the spin phase is effectively random. For the Earth's centre the window is every sidereal day, drifting with precession. The ground is always; the Galaxy and the universe never.
Why it says what it says
Why does "one year" miss by 47,000 km? A calendar year is 365.2425 days; the Earth's orbit takes 365.2564. The twenty-minute gap is 36,000 km of orbit.Why no UTC? It did not exist before 1960. Dates are local mean time at the pin, or UT.Why "longitude not knowable" at 10,000 BC? The Earth's rotation is only known to within some hours that far back, so the latitude is known and the longitude is not.Why is 66 Ma "unknowable"? The orbit's phase cannot be reconstructed past about 58 million years; the Solar System is chaotic on that timescale. The size of the orbit is fine, so the answer is a range: somewhere on it.Why do the two real machines have no miss? Time dilation moves you forward by making your clock run slow while you travel, and you fly home. You never leave the Earth's world line.Why does the picture ignore precession? It is in the numbers; drawing the 26,000-year wobble on top of the spin would hide the spin.
The worked example
St. Croix, 22 October 1902, 11:41 local mean time: the day a 32–32 tie in the Danish Landsting kept the islands Danish. Tap the preset. Fixed to the Earth's centre you come out over the Gulf of Mexico, 2,858 km away, at ground level, with the ground arriving at 443 m/s. Fixed to the Sun, 72 million km into space. Fixed to the Galaxy, 6,500 AU. Two published tables for the Earth's clock error that day differ by 0.76 s, about 340 m east–west, and the site shows both.
Relative to
Search 50 years 200 years 1,000 years Direction into the past into the future Landing = within 10 km 100 km 1,000 km
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A fun project by Brian Louden , an independent journalist on St. Croix, U.S. Virgin Islands. It is a side road from the day job: VI Update , a video and text newsroom for the territory, and USVI Public Records , a free archive of tens of thousands of government documents. Same standard, though: every number here is computed from a sourced model, and the site says how sure it is.
Free to use, share and argue with. St. Croix, 22 October 1902, is the worked example: that day a 32–32 tie in the Danish Landsting kept the islands Danish.