Definition

1. Noun:
   • The point in the orbit of a celestial body (such as the Moon or a planet) where it crosses the plane of the ecliptic (the apparent path of the Sun) moving from north to south. This is a specific term in astronomy and orbital mechanics.

Usage Examples

• Noun:
  • The spacecraft was timed to reach the descending node precisely at midnight.
  • Astronomers calculated the position of the Moon's descending node to predict the eclipse.

Advanced Usage

• "To cross the descending node": This phrase describes the moment a celestial body passes through this specific orbital point.
  • The comet will cross the descending node next week, entering the southern celestial hemisphere.

Variants and Related Words

• Ascending node (n): The opposite point where an orbit crosses the ecliptic plane going from south to north.
  • The difference between the positions of the ascending and descending nodes defines the orientation of the orbit.
• Node (n): The general term for either of the two points where an orbit intersects a reference plane.
  • The line connecting the two nodes is called the line of nodes.

Synonyms

• Southbound node: A less common descriptive synonym.
• Orbital node (southward crossing): A more detailed descriptive phrase.

Related Phrases

• Line of nodes: The straight line connecting the ascending and descending nodes.
  • The orientation of the line of nodes slowly changes over time due to gravitational perturbations.

Noun

1. the point at which an orbit crosses the ecliptic plane going south