What is a planetary occultation?

An occultation is the ultimate planetary line-up. A planetary occultation happens when a larger planetary body passes in front of a smaller one, blocking the view of the smaller one from Earth. The most common kind of occultation happens when the Moon passes in front of a planet, since it appears so large in Earth’s night sky.

Extremely rarely, a planet will occult another planet. This is so rare because planets appear very small in Earth’s skies, so their alignment has to be extraordinarily precise for them to actually produce an occultation. The next time this happens will be on Nov. 22, 2065, when Venus will occult Jupiter.

What does it mean when a planet is at conjunction?

Another term stargazers may hear is that a planet is at conjunction. The planets who orbit the Sun beyond Earth (Mars, Jupiter, Saturn, Uranus, and Neptune) are at conjunction when they are on the far side of the Sun from the Earth and all three bodies are nearly in a straight line.

When the innermost planets (Mercury and Venus) are on the far side of the Sun it is called superior conjunction. When they are between the Earth and the Sun, it is called inferior conjunction.