The Live Orrery

What you are seeing

An orrery is a working model of the solar system. This one opens on the current moment and keeps time with the clock, placing each planet where it actually is, worked out live from the same astronomy engine the rest of the site uses. Press Play and the planets move along their real orbits; tap the time to scrub through the years, step by the hour, day or month, or pick a date. Press Now to come back to the present.

Two views of the same sky

The Sun-centered (heliocentric) view is the true layout: the Sun sits at the middle and the planets, Earth among them, travel around it on their real paths. This is the map astronomers use, and it is where alignments and the Venus-Earth dance are easiest to see.

The Earth-centered (geocentric) view puts Earth in the middle. Each body sits in the direction we see it in our sky, around the ring of the zodiac, and at its true distance from us, so you can watch Mars swing close at opposition and fall far behind the Sun. The Moon is the one exception: drawn at its real distance it would sit on top of Earth, so it rides a small fixed ring.

Turn on Trails

Switch on Trails under Layers in the More menu and each body draws the path it took on the way to the moment shown; press Play and the paths grow. In the Sun-centered view the trails follow the orbits. In the Earth-centered view something stranger appears: as Earth overtakes an outer planet, that planet seems to stop, slip backward, and loop, the famous retrograde motion. The planet never reverses; we are passing it on the inside track.

Switch to the Earth-centered Inner system with Trails on and watch Venus. Each time Venus passes between Earth and the Sun it does so about 216 degrees further around the zodiac, so five passes take eight years and land almost where they began. Venus's trail keeps eight years, and those passes trace a near-perfect five-petaled rosette, the pattern explored on the Venus page.

About the scale

Space is mostly empty. Pluto is about a hundred times farther from the Sun than Mercury, so a true-to-scale map would crush the inner planets into a single dot. The All bodies view therefore uses a square-root distance scale so every body is visible at once; switch to Inner system to see Mercury through Mars at their true relative spacing. Either way the angles are real. The map is flattened onto the plane of Earth's orbit, which leaves out the small tilts of the other orbits.

We include Pluto as the outermost body. The International Astronomical Union reclassified it as a dwarf planet in 2006, but it remains a favorite, and its orbit is plotted here in full. Pluto's path is so stretched that for about twenty years, from the late 1970s to the late 1990s, it actually rode closer to the Sun than Neptune, which you can watch by scrubbing back to the 1980s and 1990s.

Moments: guided explanations

A Moment walks through one idea in a few steps on the orrery, with its dates worked out from the day you open it. It asks you to predict what happens, then shows you. Open one with the Moments button at the bottom of the orrery, or from this list:

• Why we have seasons: winter in the north comes when Earth is closest to the Sun.
• Why Mars goes backward: Earth overtakes Mars, and Mars seems to loop.
• Why the Moon has phases: half the Moon is always lit; we see a changing share of that half.
• Why there is no eclipse every month: eclipses come in seasons, about every six months.

Keyboard shortcuts

The keys work while the orrery or one of its controls has focus. Skip to the orrery, at the top of the page, goes straight to the scene; on the stage, the first control is Choose a body, a list of every body that opens its details. Ctrl, Alt and Cmd combinations, and the site search, keep their usual jobs.

Key	What it does
Space	Play or pause
Left, Right	Step a day back or forward (in a Moment, the step before or after)
Up, Down	Faster or slower
N	Back to now
Page Up, Page Down	Step a month on the time strip
Enter	On a body's label, open its details
Shift and arrows	Turn the 3D view
Plus, minus	Zoom the 3D view
H	Recenter the 3D view
F	Follow the selected body in the 3D view
Escape	Close the open panel, then leave a Moment

Accuracy

Positions come from the Astronomy Engine library, timed on Earth's measured rotation. We compared 69,402 of its places, as seen from Earth, with NASA JPL Horizons at the same moments from 1700 to 2200, and the Sun, the planets and Pluto stay within 1 arcminute across that span. An arcsecond is 1/3600 of a degree, and the Moon is about half a degree, or 1,800 arcseconds, across.

Largest difference from NASA JPL Horizons, in arcseconds, as seen from Earth, 1700 to 2200

Body	Largest	On
Sun	15.828	Dec 11, 2199
Moon	240.337	Jul 9, 2199
Mercury	37.332	Jul 14, 2199
Venus	23.634	Nov 2, 1703
Mars	23.189	Sep 27, 1830
Jupiter	16.833	Nov 19, 1715
Saturn	23.835	Dec 30, 1709
Uranus	19.570	Jan 30, 2036
Neptune	21.509	Sep 2, 1848
Pluto	51.408	May 6, 1741

The Moon first passes 1 arcminute on August 6, 2081. Its later difference comes from timekeeping rather than from its orbit, since Horizons and our engine predict Earth's future rotation differently and nobody can measure that rotation in advance.

We measured places as seen from Earth, the convention of the positions table and the Earth-centered view. The Sun-centered positions are not measured separately, and Jupiter's four large moons (Io, Europa, Ganymede and Callisto), which the 3D view draws when you zoom in on Jupiter, are not measured at all. The accuracy report has the method, each body's median and the study data.

Linking to this page

Each date, view, body and Moment has its own address, so you can link to any of them. Links keep working. Every address below is also on a fixed list that we test each time the page changes, and each one keeps opening what it opened when we added it.

t

Sets the moment shown, in UTC, as in t=2027-02-19T15:44:23Z; the seconds are optional, as in t=2027-02-19T15:44Z. The range runs from t=1700-01-01T00:00:00Z to t=2200-12-31T23:59:59Z, and any time in the last minute of 2200 opens at 23:59 UTC on December 31, where the range ends. Chat apps often write the colons as %3A, and t=2027-02-19T15%3A44%3A23Z opens the same view. A t outside the range, or written any other way, is ignored.

d

A date alone, as in d=2026-03-21, the form older links use. It opens that date in UTC at the current UTC time of day, and when a link has both, t wins.

view

view=earth opens the Earth-centered view. The Sun-centered view, view=sun, is the default.

scale

scale=true turns on True scale in the 3D view, and scale=compact is the default. The diagram ignores scale.

focus

focus=mars opens that body's card. The names are sun, mercury, venus, earth, moon, mars, jupiter, io, europa, ganymede, callisto, saturn, uranus, neptune and pluto, in any letter case. In the 3D view the camera frames the body, and a moon of Jupiter is framed through its planet.

m

Opens a Moment, one of m=seasons, m=retrograde, m=phases and m=eclipse-seasons, at a step given after a colon, as in m=retrograde:2. With a t, as in m=seasons:3&t=2026-10-14T12:00:00Z, the Moment works its dates out from that moment, so the link opens the same step with the same dates every time. Without one it starts from the day it is opened.

v

v=3d asks for the 3D view and v=2d for the diagram. Without WebGL2 a device shows the diagram either way.

utm_

Campaign tags such as utm_source=instagram change nothing on screen. Once analytics has read them, or after 20 seconds, they leave the address the next time it changes, and Share leaves them out.

As you use the orrery the address bar keeps up, writing t, view, scale, focus, m and v in that order, with t to the whole second. It changes when you pause, step or choose something, and holds still while time plays. A live view has no t, and any other key is dropped.

Frequently asked questions

What is an orrery?

An orrery is a working model of the solar system, sometimes called a solar system model or simulator, that shows where the planets are. This one is computed live: it opens on the current moment, places each planet at its real position, and animates the orbits when you press Play.

What is the difference between the heliocentric and geocentric view?

The heliocentric (Sun-centered) view puts the Sun in the middle with the planets, including Earth, orbiting it; this is the true layout of the solar system. The geocentric (Earth-centered) view puts Earth in the middle and shows each body in the direction we see it around the zodiac, at its true distance from us. This orrery lets you switch between the two.

Can I see the planets' positions for a past or future date?

Yes. Tap or click the time to open the time panel, then pick any date from 1700 to 2200 or drag its time strip through the years, and the orrery redraws the planets for that moment. Press Play to watch them move anywhere in that range, and turn on Trails to trace retrograde loops and the eight-year Venus pattern.

Are the positions accurate?

Yes. Positions come from the Astronomy Engine library, timed on Earth's measured rotation. Measured against NASA JPL Horizons, the planets and Pluto as seen from Earth stay within 1 arcminute from 1700 to 2200. The map is flattened onto the plane of Earth's orbit, so it shows each planet's direction and distance in that plane and leaves out the slight tilt of its orbit.

Why does the map stay flat?

Because all the planets orbit the Sun in nearly the same flat plane. A top-down map captures almost everything; the small angles between the orbits are why eclipses and transits are occasional rather than monthly, a story told on the eclipses and lunar nodes pages.

What is retrograde motion?

It is the apparent backward loop a planet traces against the stars when Earth overtakes it (for outer planets) or it overtakes Earth (for inner ones). Turn on Trails in the Earth-centered view and play forward to watch it happen. Nothing actually reverses; it is an effect of our moving viewpoint.