Solar System Simulator

Explore planets, moons and time.

What you are looking at

This is a model of the solar system at the date and time in the top-left corner. It opens over Earth, starting from right now and advancing at 2 hours per second so you can watch the planet turn. Day and night follow the time shown, city lights come on across the night side, and clouds drift over the oceans. Pick another body from the list or its label to switch directly, keeping your relative zoom. On a phone, swipe the planet list near the bottom to see more worlds.

Everything moves the way it really moves. The Moon keeps the same face toward Earth, Jupiter's four large moons race around it in hours and days, and Saturn's rings tilt toward or away from the Sun as the seasons of its 29-year orbit turn. The stars and the band of the Milky Way are in their true places too: 8,920 real stars, every one bright enough to see with the naked eye from a dark site.

For a model you can build, use the scale-model worksheet: choose your available distance or a model Sun or Earth size, then print or download every measurement, including the steps between markers. The planet size chart compares all eight planets on one diameter scale.

How to use the simulator

The details panel shows the selected body's size, year and live distances. On a phone, tap Details to open it. Choose a moon to visit it, or open More facts for mass, gravity, day length, axial tilt and temperature. Bodies other than Earth also show their distance and light-travel time from Earth.

Choose Whole system to see all the planetary orbits, Inner planets for Mercury through Mars, or Planet view for a close-up. Selecting a body while viewing the whole system updates its facts without moving the camera. Reset view restores the framing for the current view.

Tap the speed to choose a rate directly. Share copies the current moment, camera, selected body, speed and display settings. Pause first if you want someone to open a still view. The camera buttons zoom in, zoom out and enter Focus mode. More has planet comparisons, picture download and fullscreen controls. Choose High graphics detail there for sharper edges and the most detailed Earth and Moon maps; Auto adapts to your device. Saved pictures are drawn at the highest resolution in either mode.

Try a day on Earth

Open the day-and-night experiment. Pick a coastline, then watch the clock and the boundary between daylight and darkness. How much simulated time passes before that coastline faces the Sun again?

Pause and drag toward the night side to see the city lights. Use More → Compare planets to compare Earth's diameter with Jupiter's. The circles share one size scale; the distance and light-travel readings follow the date in the simulator.

For a different question, change a planet's launch speed in the gravity sandbox or compare bent and straight light paths around a black hole. For a game, take on the six gravity challenges, from a first orbit to a Jupiter slingshot.

Travel through time from 1800 to 2100

Time runs at speeds from real time to a year per second, forward or backward. New visits start at 2 hours per second; shared links keep their chosen speed. At one day per second you can watch the inner planets lap the outer ones. At a month per second Mars traces its looping path relative to Earth; see the dates of each Mars retrograde loop. Choose a date in the date box to jump straight to it, or press Now to come back to the present at real time.

The date range is deliberate. We compared the computed positions with NASA JPL's Horizons system across 1800 to 2100 and the simulator stays inside that tested span.

Eclipses and other sky events

The Events button lists what is coming up from the date on screen: solar and lunar eclipses, oppositions of the outer planets (when they are brightest and up all night), the greatest elongations of Mercury and Venus, and the equinoxes and solstices. Choose one and the simulator jumps to that moment and frames the scene. Under Try this, the seasons activity steps through the next equinoxes and solstices with Earth seen side-on, so you can watch which hemisphere leans toward the Sun, and a second one opens the total solar eclipse of 2 August 2027 with the Moon's shadow on Earth. To step through every solar and lunar eclipse from 1800 to 2100, one after another, open the eclipse simulator. For where that shadow touches the ground, see the 2027 eclipse path map; for local times and coverage of every eclipse in 2026 and 2027, see eclipse dates and visibility by town.

Shadows are calculated for every point on each body from the size and position of the Sun and of nearby worlds. That is how the dark spot of the Moon's shadow crosses Earth during a solar eclipse, how Earth's shadow turns the Moon a coppery red in a total lunar eclipse (sunlight bent through our atmosphere still reaches it), and how the small black shadows of Io, Europa, Ganymede and Callisto slide across Jupiter's clouds.

The sky from your location

Choose Sky to see the Sun, Moon and planets above the horizon at a chosen moment. Pick a location or open Coordinates to enter latitude and longitude, set the UTC date and time, then choose Update sky. North is at the top of the diagram; east is on the left because you are looking up. The centre is directly overhead.

The table gives each body's ecliptic longitude, direct or retrograde motion, altitude and azimuth. The Moon's phase and illuminated fraction appear beside the diagram. To check which planets are retrograde on any date, use the retrograde calendar. A body above the horizon can still be hidden by daylight or weather; these coordinates do not include atmospheric refraction.

Show this moment in 3D returns to the solar system at that exact time, paused. Export positions saves the coordinates and their assumptions as a local JSON file. Your entered location stays on your device. See how the sky coordinates are checked.

True scale, and why space looks empty

Sizes and distances are true unless you turn on Enlarge. The distances are hard to imagine: light from the Sun takes about 8 minutes 20 seconds to reach Earth and over 4 hours to reach Neptune. Zoom out to see the whole system and the planets shrink to points, so each is marked with a small ring and its name. Enlarge draws the planets, and the orbits of their moons, 20 times larger so you can see them as discs from farther away; it is labelled because it is not to scale.

How accurate is it?

For a fixed reference beside the simulation, use the eight-planet size comparison and fact table. Download the diagram for a lesson or the CSV for a spreadsheet. Its diameters share one scale; its mean orbital distances are reference values rather than positions at the selected date.

Positions come from established orbital theories rather than from a fixed animation. We test them against NASA JPL's Horizons system, the reference ephemeris used for spacecraft navigation:

• Planets and Pluto: within 30 arcseconds of Horizons at every sample from 1800 to 2100, about the width of Jupiter's disc as seen from Earth.
• The Moon: within 5 arcseconds and 25 km (2020 to 2030).
• Jupiter's four large moons: within 700 km.
• The other moons: from JPL's published mean orbits, adjusted to match Horizons; most stay within about 2 degrees of their true place around their planet.

The 3D positions are geometric. The Sky inspector separately computes Earth-observed coordinates, including light-travel and aberration corrections for the planets. Accuracy and sources explains the methods, time conventions and tests in full.

Choose the model for your question

Use this view to explore the solar system at a chosen date. To add a body and see how the orbits change, open the gravity sandbox; it evolves its own Newtonian system from the starting conditions. For light bending around a non-rotating black hole, use the black hole simulator. These models answer different questions and have separate accuracy limits.

Compare the eight planets

The inner planets are small beside the gas and ice giants. These circles use one diameter scale, so Earth is about one-eleventh the diameter of Jupiter. Distances between circles are for layout only.

Approximate fact-sheet values; an Earth day is the orbital-period unit.

Planet	Diameter (km)	Mean Sun distance (million km)	Year (Earth days)
Mercury	4,879	57.9	88
Venus	12,104	108.2	224.7
Earth	12,756	149.6	365.2
Mars	6,792	228	687
Jupiter	142,984	778.5	4,331
Saturn	120,536	1,432	10,747
Uranus	51,118	2,867	30,589
Neptune	49,528	4,515	59,800

Mean distances are reference values, not today's separation from the Sun or Earth. Select a planet above to see the live distances for the displayed date. The gravity sandbox lets you experiment with a separate model of orbital motion.

Download size chart (SVG) · Download planet table (CSV)

Source: NASA's Planetary Fact Sheet, using the simulator's September 26, 2026 snapshot. Read accuracy and sources for the model's separate position checks.