Field guide · Reading the sky
ConstellationSigns and constellations
Not any more. A sign is a twelfth of the year, counted from the March equinox; a constellation is a patch of sky. They matched about two thousand years ago and have slid almost a whole sign apart since.
- Signs
- Twelve, each 30° of the ecliptic
- Counted from
- The March equinox
- Constellations the Sun crosses
- Thirteen, all different lengths
- Drift since they matched
- Almost a whole sign
The Babylonians cut the Sun’s yearly path, the ecliptic, into twelve equal slices of 30° and named each after a constellation near it. Greek astronomers counted the slices from the March equinox, so the sign of Aries always begins on the first day of northern spring, whatever stars are behind the Sun.
The constellations are fixed to the stars instead, and since 1930 they have been regions with borders, drawn unevenly. Virgo holds more than six times as much of the ecliptic as Scorpius, and Ophiuchus holds a stretch no sign was ever named for. So the Sun crosses thirteen constellations, and spends a different time in each.
Precession slides the equinox west along the ecliptic, a degree every 72 years, and the signs slide with it. The equinox left Aries for Pisces in 68 BC, so for most of any sign the Sun is in the constellation before it. Neither is wrong: a sign tells the season, a constellation where to look.
The signs in 2026
Each sign's dates, and where the Sun really is while it runs. Dates in UTC; a day either side elsewhere.
| Sign | The Sun is in |
|---|---|
| Aries 20 Mar – 20 Apr | |
| Taurus 20 Apr – 21 May | |
| Gemini 21 May – 21 Jun |
|
| Cancer 21 Jun – 22 Jul | |
| Leo 22 Jul – 23 Aug | |
| Virgo 23 Aug – 23 Sep | |
| Libra 23 Sep – 23 Oct |
|
| Scorpio 23 Oct – 22 Nov | |
| Sagittarius 22 Nov – 21 Dec |
|
| Capricorn 21 Dec – 20 Jan |
|
| Aquarius 20 Jan – 18 Feb |
|
| Pisces 18 Feb – 20 Mar |
See it in the sky
Each one opens the sky map pointed at it, for tonight, from where you are.