Phases of the Moon: Angular Separation Question

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SUMMARY

The discussion centers on the angular separation of the Moon during its First and Last Quarter phases, which is definitively 90 degrees. This angular separation refers to the true angular separation rather than merely the difference in ecliptic longitudes. The relationship between the Earth-Moon line and the Earth-Sun line is crucial in understanding this phenomenon. Kepler confirms that the 90-degree separation occurs when the Earth-Moon line is perpendicular to the Earth-Sun line.

PREREQUISITES
  • Understanding of lunar phases, specifically First and Last Quarter.
  • Basic knowledge of angular separation in astronomy.
  • Familiarity with ecliptic coordinates and their significance.
  • Concept of the Earth-Moon and Earth-Sun lines in celestial mechanics.
NEXT STEPS
  • Research the mathematical calculations for angular separation in astronomy.
  • Explore the significance of ecliptic longitudes in lunar phases.
  • Learn about the geometry of the Earth-Moon-Sun system.
  • Investigate the effects of lunar phases on tides and other Earth phenomena.
USEFUL FOR

Astronomy enthusiasts, students studying celestial mechanics, educators teaching lunar phases, and anyone interested in the geometric relationships in the Earth-Moon-Sun system.

kepler
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Hi,

Just a stupid doubt...when the moon is in FIRST QUARTER or LAST QUARTER, their angular separation is of 90 degrees; question: is it the TRUE angular separation or is it the difference of ecliptic longitudes?

Kind regards,

Kepler
 
Astronomy news on Phys.org
First and last quarter moons result from the earth-moon line being 90 deg. from the earth-sun line.
 
That was my initial guess :)

Thanks,

Kepler
 

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