AST101H1 Lecture Notes - Lecture 5: Angular Diameter, The Moons

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Bryan Gaensler

Document Summary

Only half of the moon is illuminated at any one time. The phase changes as the moon orbits the earth. The moon rotates as it orbits, so the same side always faces the earth. The far side of the moon can never be seen from earth. When aligned right, the moon can cast a shadow on the earth (solar eclipse) or the earth can cast a shadow on the moon (lunar eclipse) Solar eclipse has to happen on a new moon but not always. The moons orbit is not quite circular. When it is closer, it appears a little bigger. The angular size of the moon and the sun are nearly the same, so the moon almost perfectly covers the sun. If an eclipse happens when the moon is further from the earth in its orbit, the center off the shadow sees an annular eclipse. In a lunar eclipse, the earth casts a shadow on the moon.