This can occur when two planets, for example, are on opposite sides of the sun and therefore appear close to each other in the sky, or when a planet and a moon or a planet and a comet are in close proximity. Conjunction can also refer to the alignment of a spacecraft or satellite with a celestial body, for example, a spacecraft going into orbit around a planet or moon.
Examples of conjunction in aerospace context:
- In 1991, NASA's Voyager 1 spacecraft flew by a conjunction of Jupiter and its moon Europa, allowing scientists to study both bodies at the same time.
- In 2022, Venus and Jupiter will be in a close conjunction, appearing less than 1 degree apart in the night sky.
- In 2026, Mars and Earth will be in a close conjunction, allowing for a rare opportunity for a spacecraft to be launched from Earth and take advantage of the planets' relative proximity to each other to make the journey to Mars more efficient.
- In 2040, Saturn and Jupiter will be in conjunction, both planets will be within 1 degree of each other, providing a unique opportunity for scientific study and observations.