We've changed our name — alarm-clock.org is now timeandspace.science. Same tools, same pages, new address.
Mercury, Venus, Earth and Mars on their real orbits, to scale with each other. Drag through a month, a year or a decade and watch the inner four lap one another.
Thu, August 13, 2026
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Jump to Earth & the Moon Asteroid belt Jupiter’s moons Saturn’s rings The outer planets
Distances from the sun are in AU — one AU is the Earth’s average distance, 149,597,870 km — and the angle is where the body sits around its orbit, measured from the March equinox direction.
All four rocky planets fit inside 1.62 AU — the outermost, Mars, orbits only 3.9× further from the sun than the innermost, Mercury. That is why a diagram of the whole solar system shows them as a knot in the middle: on the scale that reaches Neptune, this entire picture is the first few percent of the width.
| Planet | Distance from the sun | Year | Diameter | Moons drawn |
|---|---|---|---|---|
| Mercury | 0.387 AU | 0.24 y | 4,879 km | 0 |
| Venus | 0.723 AU | 0.62 y | 12,104 km | 0 |
| Earth | 1.000 AU | 1.00 y | 12,742 km | 1 |
| Mars | 1.524 AU | 1.88 y | 6,779 km | 2 |
Every figure is worked out from the same orbital elements the picture is drawn with — the year from Kepler's third law, the distance from the semi-major axis — so the table and the drawing cannot disagree. This frame holds 4 of the nine bodies the simulator draws.
The planet itself — turning on its axis, with its moons, its mass and gravity worked out from its own GM rather than copied in, and what has been learned about it lately.
Or climb the whole ladder on the solar system simulator, which is the page about how much the scale changes between these two views.
The date, the zoom, the span, the speed, the layers and any flight path are all in the address bar, so copying the URL shares exactly what is on screen. Set it up above, then take the link — it is the quickest way to hand a class one specific thing to look at.
This one is about the whole system. If the question is where the sun and the moon are from where you are standing — what time the sun comes up, why tonight's moon is the shape it is — that is the Sun, Earth & Moon movement simulator, which has a page for every city and a slider over a day, a week or a month. Between the two is the three bodies moving together — Earth going round the sun, the moon going round the Earth, on one screen and openly not to scale, keeping only the real ratio between the two periods.
And for why any of it stays up: the orbital velocity simulator takes one planet and lets you set its distance and its sideways speed by hand, so you can watch the balance that holds every orbit here — and break it, into an ellipse, an escape, or a fall into the sun.
Also: the classroom guide · sunrise & sunset by city · moon phase & moonrise · lunar eclipses · how the positions are worked out