# Transit

Also called: shadow transit, meridian transit.

When a small body crosses the face of a larger one — a moon over Jupiter, or Mercury over the Sun.

Jupiter's moons and their shadows regularly cross the planet's disk: the shadow is a sharp black dot, the moon itself is hard to spot against the clouds. Mercury and Venus occasionally transit the Sun (only ever observe the Sun with a proper solar filter).

Astronomers also say an object transits when it crosses the [meridian](https://astropilot.space/glossary/meridian) — that's when it's highest.

**Examples:** [jupiter](https://astropilot.space/object/jupiter.md), [io](https://astropilot.space/object/io.md), [ganymede](https://astropilot.space/object/ganymede.md)

**Related:** [Occultation](https://astropilot.space/glossary/occultation.md), [Galilean moons](https://astropilot.space/glossary/galilean-moons.md), [Meridian](https://astropilot.space/glossary/meridian.md)

From the AstroPilot astronomy glossary: https://astropilot.space/glossary/transit