astronomy/source/js

API Reference

Astronomy : object

Kind: global namespace

• Astronomy : object
  • .ElongationEvent
    • new ElongationEvent()
  • .Elongation(body) ⇒ ElongationEvent
  • .SearchMaxElongation(body, startDate) ⇒ ElongationEvent

Astronomy.ElongationEvent

Kind: static class of Astronomy
See: Astronomy.Elongation
Properties

Name	Type	Description
time	Time	When the event occurs.
visibility	string	Either "morning" or "evening", indicating when the body is most easily seen.
elongation	number	The angle in degrees, as seen from the center of the Earth, of the apparent separation between the body and the Sun. This angle is measured in 3D space and is not projected onto the ecliptic plane.
relative_longitude	number	The angle in degrees, as seen from the Sun, between the observed body and the Earth. This value is always between 0 and 180. More precisely, relative_longitude is the absolute value of the difference between the heliocentric ecliptic longitudes of the centers of observed body and the Earth.

new ElongationEvent()

Represents the visibility of a planet or the Moon relative to the Sun. Includes angular separation from the Sun and whether visibility is best in the morning or the evening.

Astronomy.Elongation(body) ⇒ ElongationEvent

Calculates the absolute value of the angle between the centers of the given body and the Sun as seen from the center of the Earth at the given date. The angle is measured along the plane of the Earth's orbit (i.e. the ecliptic) and ranges [0, 180] degrees. This function is helpful for determining how easy it is to view Mercury or Venus away from the Sun's glare on a given date. The function also determines whether the object is visible in the morning or evening; this is more important the smaller the elongation is.

Kind: static method of Astronomy

Param	Type	Description
body	string	The name of the observed body. Not allowed to be "Earth".

Astronomy.SearchMaxElongation(body, startDate) ⇒ ElongationEvent

Searches for the next maximum elongation event for Mercury or Venus that occurs after the given start date. Calling with other values of 'body' will result in an exception. Maximum elongation occurs when the body has the greatest angular separation from the Sun, as seen from the Earth. Returns an object containing the date and time of the next maximum elongation, the elongation in degrees, and whether the body is visible in the morning or evening.

Kind: static method of Astronomy

Param	Type	Description
body	string	either "Mercury" or "Venus"
startDate	Date	the date and time after which to search for the next maximum elongation event