Sun, Earth and Moon Simulator

Pick a date or press play. See where Earth is in its orbit, which season it is, and what phase the Moon is in.

Click a month to jump to its 1st. All dates are UTC. Moon phase dates use the average lunar cycle, so they can be off by up to about a day. Eclipse hints are approximate.

How it works

Pick a date, step by day or month, drag the day-of-year slider, or press play and watch the year run. The orbit view shows Earth going around the Sun, with the orbit split into four season colors for the Northern Hemisphere. The Moon card shows the phase as seen from Earth, how much of it is lit, and its age in days. The globe card shows where the Sun is directly overhead. The table lists all twelve months: where Earth is on the 1st, both hemispheres' seasons, the Moon on the 1st, and the new moon, full moon, and equinox or solstice dates. Click any month row to jump to its 1st. Press Space to play or pause, and the arrow keys step by day.

FAQ

Is the Moon's orbit drawn to scale?

No. The Moon's orbit and the sizes of the Sun, Earth, and Moon are not to scale, or the Moon would be too small to see. The orbit shape is also exaggerated four times so its oval shape shows up.

Why can a new moon or full moon date be off by a day?

The Moon dates use the average lunar cycle of about 29.53 days. The real cycle varies a little, so a listed date can land about a day away from the true one.

What do the four orbit colors mean?

They are the Northern Hemisphere seasons: green for spring, yellow for summer, orange for autumn, and blue for winter. The Southern Hemisphere has the opposite season at the same time, and the table shows both.

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