Field guide · Reading the sky
ConstellationEcliptic and zodiac
The Sun’s path through the stars over a year. The Moon and planets stay near it too, which is why they are always found in the same band of constellations.
- Tilted
- 23.4° to the celestial equator
- Constellations crossed
- 13, including Ophiuchus
- Who stays near it
- Sun, Moon and planets
As the Earth orbits, the Sun appears to move against the background stars, going once around the sky in a year. Its path is the ecliptic — named because eclipses can only happen when the Moon is on it too.
The planets all orbit in nearly the same plane as the Earth, so they also wander along the ecliptic, never straying far. The constellations it passes through are the zodiac. Astronomically there are thirteen, not twelve: the Sun spends two and a half weeks from late November in Ophiuchus.
On a clear moonless evening you can sometimes see the ecliptic itself: the zodiacal light, a faint cone of sunlight scattered by dust in the plane of the planets.
See it in the sky
Each one opens the sky map pointed at it, for tonight, from where you are.