Transit & Occultation

5.8 - Understand the terms:
d) transit
e) occultation

A transit is the passing of one body in front of another body or celestial line.

From Earth we can view transits of Mercury and Venus when these inferior planets pass in front of the Sun.

Transits of Venus are rare. The last transit was in 2004, the first in 120 years. The next is in 2012.


An occultation is like a more dramatic transit where one celestial body obscures and covers another and so blocks its light. This is typically the Moon occulting (hiding) a planet or star or a planet occulting a star.

From observing occultation scientists can collect accurate data about the position of bodies in the sky.

The satellites of Jupiter are seen to be occulted by the planet when they move behind and they also transit Jupiter's surface when they orbit in front of the planet.

An eclipse is technically an occultation AND a transit. The Moon blocks the Sun. In a lunar eclipse, the Earth blocks the Sun from the Moon.


  • Explain the terms transit and occultation
  • Discuss if an eclipse of the Sun (by the Moon) is a transit, an occultation or both

There are two similar meanings of transit:

  1. A transit is one body moving in front of another
  2. It is sometimes used instead of culmination when a body moves across a meridian line


Catching the Light by Jerry Lodriguss Moon occulting Venus

Exploratorium Transit of Venus