Sun, Moon & Earth Movement Simulator for Johannesburg
Where the sun and the moon are from Johannesburg, at any moment you choose. Today the sun rises at 6:45 AM and sets at 5:44 PM — 11 h 0 m of daylight — and the moon is a last quarter, 51% lit. Drag the slider through a day, a week or a month and watch all of it move.
Showing Johannesburg
-26.200°, 28.050° — Africa/Johannesburg
Thu, Aug 6, 2026, 12:42 AM
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Johannesburg is the marker on the globe — on the night half right now, riding the dotted circle its spot traces as the Earth turns. The moon is 92° from the sun in the sky now, and that angle is the phase: last quarter. You are looking down on the Earth from far above its orbit, from the south — the side you are on — with sunlight arriving from the top left, so the half of the Earth facing that way is the half having its day. Sizes and distances are not to scale; the directions are.
What Johannesburg’s latitude does to the picture
At 26.2° south, Johannesburg has a moderate swing through the year — 13 h 47 m of daylight at the longest day and 10 h 30 m at the shortest — and the sun never quite reaches straight overhead.
Baked for the moment this page was built; the simulator above recomputes everything in your browser for whatever instant you set.
This picture is not to scale — here is how far out it is
Every direction and angle in the simulator is real. Every size and distance is not, and it is worth being exact about which, because a diagram that quietly lies about the solar system is how people end up thinking the moon is a few Earth-widths away.
Try it in a corridor. Shrink the Earth to a 16 mm marble. The moon is then a 4.4 mm bead — about a peppercorn — held 48 cm away. The sun is a 1.7 metre ball, taller than a person, standing 188 metres down the road: two football pitches. Nothing about that fits on a screen, so this picture keeps the angles honest and lets the distances go.
What you can trust here: the direction of the sun and the moon from the Earth and from your own spot; which half of the Earth is in daylight; the angle between the moon and the sun, which is the phase; the tilt of the Earth’s axis and how much of your daily circle falls in the light. What you cannot: any distance, the sun’s size, or anything about eclipses.
Things the picture is quietly telling you
Each of these is something you can make the simulator do, rather than something to take on trust.
The moon keeps one face turned to us
The moon turns on its own axis exactly once for every trip round the Earth — 27.3 days for both — so the same hemisphere faces us permanently. That is why the phase disc beside the read-out always shows the same markings whatever the phase: the shape of the lit part changes, the face does not. It is not a coincidence; Earth’s pull has slowed the moon’s spin over billions of years until the two matched, which is called tidal locking. A wobble in the orbit (libration) lets us peek round the edges, so about 59% of the surface has been seen from Earth over time — the rest only from spacecraft.
Which makes “the dark side of the moon” a misnomer. The far side gets exactly as much sunlight as the near side — at new moon the far side is the fully lit one. It is the far side, not the dark one.
Why the moon rises later every day
Set the span to a month and watch the moonrise row. Each day it slips later — about 50 minutes on average, though it ranges from roughly 30 to 70 depending on latitude and time of year. The reason is in the picture: while the Earth spins once, the moon has moved on around its orbit by about 13°, so your spot has to turn that bit further to catch up with it.
Two different “months”
The moon takes 27.3 days to go once round the Earth against the background stars, but 29.53 days to get back to the same phase. The extra two days are because the Earth has moved along its own orbit in the meantime, so the sun is in a slightly different direction and the moon must travel a little further to line up with it again. The phase cycle you can watch here is the second one.
Everyone sees the same phase, the right way up for them
The phase is a fact about the whole Earth–moon system, so at any instant it is identical from every country: this page shows the same percentage lit for Oslo and for Cape Town. What changes with location is the orientation — a crescent that opens to the right in the northern hemisphere appears to open to the left in the southern, and near the equator it can sit like a bowl. The phase disc on this page is drawn the right way up for the place you have chosen.
Why there isn’t an eclipse every month
Line the moon up with the sun in this picture and you have a new moon; put it opposite and you have a full moon. If the orbit were flat, that would mean a solar eclipse and a lunar eclipse every single month. It is not flat: the moon’s orbit is tilted about 5.1° to the plane of Earth’s orbit, so at most new and full moons it passes above or below the line instead of through it. This flat view is looking straight down that tilt, which is precisely why it cannot show eclipses and does not try to.
The tides are in here too
The moon does most of the pulling on the oceans and the sun about half as much. When the two line up — new moon and full moon — their pulls add and the tide runs to its biggest (spring tides); when they sit square on at the quarters the pulls fight and it runs to its smallest (neaps). Drag through a month and watch the moon–sun angle: 0° and 180° are spring tides, 90° and 270° are neaps. The coast follows a day or two behind, and the shape of the shore matters as much as the sky does.
Johannesburg on the rest of the site
Nearby, for a side-by-side: Cape Town (784 mi) · Zanzibar (1567 mi) · Nairobi (1817 mi) · Lagos (2801 mi) · Malé (3693 mi) · Riyadh (3731 mi).
Using it in a classroom
The controls are the lesson. A few that work:
- Why do we have day and night? Set the span to a day and press Play. The Earth turns; the marker rides its dotted circle in and out of the lit half. Nothing about the sun moves.
- Why does the moon have phases? Leave the span on a month and play it. The moon goes right round the Earth in 29.53 days, and the phase disc changes because the ANGLE between the moon and the sun changes — not because anything covers the moon up.
- Why are days longer in summer? Compare 21 June with 21 December at the same time of day. Watch the axis lean, and watch how much of the dotted circle sits in the light.
- What happens at the poles? Try a far-northern place in June: the daily circle never leaves the daylight, which is the midnight sun.
- Compare two places at the same instant. Open two city pages in two tabs with the same date and time — two screens, one sky.
Ages roughly 9 and up. Pair it with the scale card above — the corridor version, walked out with a marble and a peppercorn, is the part students remember.
Make a link to a particular sky
Pick a place, a starting date and time and how much time the slider should cover. The link builds itself as you choose, and the sentence under it says in words where that link goes — so you can check it before you send it.
What the parameters mean
citya city slug — ?city=seattlelat & lonany coordinates — ?lat=47.6&lon=-122.33, with optional name and tzdateYYYY-MM-DD, the day the span startstimeHH:MM in the place’s own clockspanday, week or monthCity slugs are the ones in the address of a city page: /sun/seattle/. Coordinates win if you give both.
Simulator FAQ
Is this drawing to scale? No, and it cannot be. The moon is drawn about 27 times too close to the Earth, and the sun about 5,144 times too close and 114 times too small. Shrink the Earth to a 16 mm marble and the moon is a 4.4 mm bead about 48 cm away, while the sun is a 1.7 m ball roughly 188 m down the road. What IS true here is every direction and angle: where the sun and moon lie around the Earth, which half of the Earth is lit, and where you are on it.
What am I looking at? The Earth from far above its orbit, looking down from your own hemisphere. Sunlight arrives from the top left, so the half of the Earth facing that way is having its day. The marker is the place you chose, the dotted circle inside the globe is the path that spot rides as the Earth turns, and the moon sits at its true angle from the sun.
Why does the moon always look half lit? Because from this vantage you are looking at the moon side-on: the sun lights one half of it, and from above you see the boundary edge-on. The phase people see from Earth is not how much of the moon is lit — it is how much of the lit half faces us, and that is the ANGLE between the moon and the sun in this picture. Line the moon up with the sun and it is a new moon; put it opposite and it is full. The phase disc beside the read-out shows the same instant as it looks from the ground.
Why do we always see the same side of the moon? Because the moon turns on its own axis exactly once per orbit — 27.3 days for both — so the same hemisphere faces us permanently. Earth's pull slowed its spin over billions of years until the two matched, which is called tidal locking. A wobble in the orbit lets us see about 59% of the surface over time. It also means "the dark side of the moon" is a misnomer: the far side gets exactly as much sunlight, and at new moon it is the fully lit one.
Does it show eclipses? No — deliberately. Earth's real shadow reaches well past the moon's orbit, so drawing it would put the moon inside it at every full moon and imply an eclipse every month. What actually decides an eclipse is how far the moon sits above or below the plane of Earth's orbit, and that is the one thing this flat view cannot show. Lunar eclipses have their own pages.
How accurate are the positions? The sun and moon positions come from the same solver the rest of the site uses — good to about a minute of time for sunrise and sunset, and to a fraction of a degree for the moon. It runs entirely in your browser, so nothing is cached or stale. The methodology pages set out where each figure stops being reliable.
Can I share the exact view I am looking at? Yes. The location, date, time and span are all in the address bar, so copying the URL shares the exact sky on screen. The link builder further down writes one for you if you would rather fill in a form than edit a URL.
How the positions are worked out, and where they stop being reliable: sunrise & sunset, moon phase.