Event type: solar eclipse
Involved objects (check the boxes):

• Sun
• Earth's moon
• Planets

Definition of the event:

A solar eclipse occurs when a portion of the Earth is engulfed in a shadow cast by the Moon which fully or partially blocks sunlight. This occurs when the Sun, Moon and Earth are aligned. Such alignment coincides with a new moon (syzygy) indicating the Moon is closest to the ecliptic plane. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In partial and annular eclipses, only part of the Sun is obscured.
— Wikipedia

Other useful information (implementation proposal, etc): three kinds of solar eclipses have to be taken in account:

• Total eclipse: the disk of the Sun is fully obscured by the Moon
• Partial eclipse: the moon obscures only a part of the Sun's disk, forming a solar crescent
• Annular eclipse: very similar to total eclipses, but the Moon is to far away to cover the entire solar disk, making it appear as a ring.