Everything Time
Everything time and space. Keep time, then understand it: alarms and timers, sunrise and moonrise, tides, and the planets where they actually are. Built for classrooms and for the curious.
Clocks, and what they are counting. An alarm, a timer, a stopwatch, every time zone at once, and a countdown to the day you are waiting for. All of it runs in the browser, with nothing to install and no sign-up.
Your own sky, worked out for your own town. Sunrise and sunset, tonight's moon and how full it is, and when the tide turns — for more than a thousand cities, on whatever date you pick. Every figure is computed from the real motions rather than looked up in a table.
Where everything actually is, right now. The planets on their real orbits, a page for each one turning on its own axis, the moons that go round them, and the next launch window to Mars. The positions are solved when the page loads, not drawn from memory.
Made to go on a projector. A timer big enough to read from the back, four stopwatches at once, and simulators you can drag through a day, a month or a century. The guide sets out what a browser timer can and cannot be trusted with — before a lesson depends on it.
Open to see the full screen bedside clock.
- Lap 300:04.5100:12.47
- Lap 200:03.8600:07.96
- Lap 100:04.1000:04.10
Event countdowns
Live countdowns to birthdays, holidays, sports and the days you're waiting for.
Sunrise & Sunset
The cities below run north to south. The farther from the equator, the more day length swings with the season — long summer days, short winter ones.
Where the sun and moon are from your town, at any moment.
The planets where they actually are today.
Each one turning on its own axis, with its moon system, its year and gravity worked out from its mass rather than copied in, and what has been learned about it lately.
All of them →When the next window to Mars, Jupiter or Saturn opens, how long the flight takes and what it costs in speed — every date solved from the real orbits, and the path drawn so you can fly it.
Rocket launches & launch windows →Using this in a classroom
Everything here runs on a projector, needs no sign-up, no login and no install, and works on whatever the school has. Below are nine things to actually do with it — each one specific enough to run tomorrow.
And a promise about the numbers. Every figure on this site is worked out from the real motions rather than looked up, and where a picture is not to scale we say so on the picture, in numbers. A lesson built on a simulation should know which parts are measurements and which are drawing decisions — because a student will ask, and "is that real?" deserves a straight answer.
The full teacher's guide → — keyboard shortcuts, projector setup, lap export, and what a browser timer can and cannot be trusted with.
Put a one-minute timer on the board and ask the class to close their eyes and put a hand up when they think the minute is up. The spread is the lesson: hands go up from about 35 seconds to well past 90, and nobody believes that until they have seen it. Run it again after telling them the answer and watch the spread narrow — that is calibration, and it is the whole idea behind why we measure things instead of estimating them.
Where we took a liberty The timer is honest about its own limits: a browser timer can drift if the tab is buried or the laptop sleeps, and we measured by how much rather than assuming.
Four stopwatches at once, four groups, one repeated task — how long to fill a beaker, walk the length of the room, solve one long-division problem. Every lap is kept, and the fastest, slowest and mean are worked out for them. Then ask the question that matters: which of those three numbers should we report, and who does each one flatter?
Where we took a liberty Laps are recorded to a hundredth of a second, which is real; whether a human thumb on a key is accurate to a hundredth of a second is not, and it is worth saying so out loud.
Open your own town and one far north — Anchorage — and one near the equator, and put the three day lengths side by side. Then step the date forward a month at a time using the date picker. The equator barely moves. Yours swings by hours. Anchorage swings by most of a day. Ask them to explain it before you show them the tilted Earth — the guesses are the good part.
Where we took a liberty Every sunrise here is computed in the browser from the date and the place, never looked up, so any date works. It assumes a flat horizon: a mountain to your east will make the real sunrise later than the page says.
Before a lesson on phases, ask each student to draw the shape they expect the moon to be tonight. Then open the moon page for your town. Then — and this is the part that sticks — set it forward a week and ask them to draw that one too, and give them a reason to go outside on the night and see whether they were right. A prediction that can be checked is a different thing from a fact that must be believed.
Where we took a liberty The phase, the illumination and the rise and set times are solved from the real orbit for your location. The moon glyph is drawn from the real lunar near side at its real coordinates, so the dark patches are where they actually are.
The Sun, Earth and Moon simulator is set to your town and can be dragged through a day, a week or a month. Drag a single day and watch the lit half of the Earth turn under your city — that is a day. Then jump six months and do it again. The class can see that nothing about the Earth changed; only where it is standing did. Nearly every misconception about seasons dies right there. Then take them outside and build it. A 60 cm beach ball is the sun; the Earth is a 5.5 mm marble and the moon a 1.5 mm peppercorn held 17 cm from it — and the marble has to stand 65 metres away across the field. Two children can hold the whole Earth–moon system in their hands and still not be able to shout to the sun.
Where we took a liberty This one is deliberately not to scale. The moon is drawn 23 times too close and the sun 3,151 times too close and 52 times too small, and the page prints those exact numbers rather than hiding them, because a picture that fits on a screen cannot also be to scale. What IS true: the directions, the phase, and which half of the Earth is lit.
Every textbook diagram of the solar system is a lie of spacing — eight planets neatly spread across a page. Start the solar system simulator at the inner planets, then climb the zoom ladder one rung at a time to Neptune and Pluto. By the last rung the inner four are a single knot in the middle. Ask what that means for how long anything takes to get anywhere, and you have set up the launch window lesson for free.
Where we took a liberty The orbits are to scale within each view and the positions are solved when the page loads. The planets themselves are not to scale — at the Saturn view, Jupiter would be three thousandths of a pixel across. The dots are sized to be seen, and the page says so.
Ask the class how you would fly to Mars. Someone will say "point at it". Then open rocket launches and show them the next real window, worked out live, and the fact that it only comes round every 26 months. The killer table is the one comparing what real missions did against the cheapest possible route: Voyager 2 reached Saturn 833 days FASTER than the cheapest route allows, because Jupiter threw it. Gravity assists stop being magic and become arithmetic.
Where we took a liberty The flight paths drawn are minimum-energy transfers — the cheapest route, and the reference every real mission plan is measured against. They ignore orbital tilt and gravity assists, and the page states all three.
Tides are the one place a student can watch the moon do something to the Earth. Open a station near you — or any coast you have been to — and put today's curve on the board. Two highs, two lows, and they shift later each day by roughly the same amount the moon rises later each day. Then open the simulator alongside and line the sun and moon up: that is a spring tide, and the curve on the tide page will be taller that week.
Where we took a liberty These are astronomical predictions from NOAA — the sun and moon only. Real water is also pushed about by wind and air pressure, so the sea on the day can differ from the prediction, and this page never claims otherwise.
Put the day-and-night map from the front page on the projector and ask who, right now, is asleep. Then ask why the line is not vertical — and let them work out that the tilt they learned about for the seasons is the same tilt bending that line. Finish by picking a country the class has a connection to and finding out what time it is there and whether anyone would answer the phone.
Where we took a liberty The lit and dark halves are solved from the sun's real position and updated every minute in the browser. It is a flat map of a round Earth, so the shapes near the poles are stretched — which is itself a good question to ask a class.
What would make this better for your class?
Ask us for a simulator. Not a countdown — something scientific: a tool that shows how a thing actually works, of the kind the rest of this site is made of. What would make a concept land for your class if they could see it move? That is the ask, and we take it as a challenge: tell us and we will try to build it in the shortest time we can, so your class finds out that asking for something well can make it exist.
What we can build. Everything here comes out of orbits, formulas and real measurements, so anything of that kind is within reach: an alignment, a cycle, a comparison, a scale, a body we have not drawn, a figure worked out a different way. If it can be computed, it can probably be shown. Purely creative asks — a story, a game, artwork — we probably cannot do, and we would rather say so now than leave you waiting.
The best asks help more than one class. If it would work for your students it will very likely work for a class three states away, and that is what turns one request into a page. So aim at the idea rather than the worksheet.
Ask as a class, not as thirty students. Make the ask part of the lesson — let them argue about what would actually help — then send one email from the class rather than one each: “Request from Ms Thomas's 3rd grade class — Chico, CA”. We will do our best to reply to every one.
If we build it, your class gets the credit, on the page it inspired: “Ms Thomas's 3rd grade class, 2026–2027 school year — Chico, CA.” That line is worth more than it looks. It is a public page, on the open internet, that exists because your students asked for it — something they can show a parent, a head teacher, or each other years from now, and point at the part that is theirs. Not many school assignments end with proof that the work changed something outside the room.
Ask for something for your class →
If it is a bug or something plainly wrong, report it here instead — those get fixed first.
Can't find it? Suggest a birthday, holiday or event and we'll consider adding a countdown for it.
Guides: using the timer & stopwatch in a classroom · how these numbers are worked out · how it works · browser limitations · about this site.