Planisphere

A star wheel for any latitude, any century.

Chart theme

Build your instrument

View assembled wheel ↓

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Star wheel settings and downloads

Negative = BCE (astronomical year numbering: year 0 = 1 BCE, so -699 = 700 BCE).

The date scale is calibrated for this year.

Use mean solar time for your site. Convert your civil clock below, or set mean time directly.

Convert a civil clock

Enter the clock's UTC offset on that date, including daylight saving. No time zone is guessed.

Civil clock = UTC + offset. Use +00:00 for a UTC clock.

West is negative. A preset supplies longitude; custom latitude needs an explicit longitude here.

The wheel uses quarter-hour ticks. Conversion uses UTC + longitude/15; it does not calculate sundial time or validate local time-zone rules. Time-setting guide.

Two sheets, one instrument. Print at 100% and check the 50 mm scale bar.

Assembled view

Your opaque-paper star wheel

Preview view
Planisphere disc preview

Drag the rim. The red guide aligns date and mean time.

Sidereal alignment
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Visible declination limit
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Make the sky turn

  1. Print and cut both red outlines. Cut the holder’s two windows; retain the narrow supports and center hub.
  2. Place the smaller holder over the star wheel. Loosely fasten the center holes with a paper brad.
  3. Turn a date tick on the outer rim to an hour tick on the holder. Compass letters mark the horizon; the hub and supports hide a small strip.
Assembly and time-setting guide →