ASTR 1010 1st EditionLecture 16Outline of Last Lecture I. Lunar PhasesA. PhasesB. DiagramOutline of Current LectureI. Dark Side of the MoonII. EclipsesA. Lunar EclipseB. Solar EclipseCurrent LectureI. Dark Side of the Moon- If the moon rotated faster or slower we would be able to see all of its surface overthe course of several months- The Earth forced the moon to rotate at its speed and the moon is trying to do the same to Earth.II. EclipsesA. Lunar Eclipse- Moon moves into the shadow Earth casts. Only occurs at full moon.- Partial Lunar Eclipse: occur more often than total lunar eclipse: roughly every 18 months- Total Lunar Eclipse: lasts no more than 100 minutes- During TLE, the moon looks red due to a small amount of red light refracted through Earth’s atmosphereB. Solar Eclipse- Moon casts shadow on Earth. - Can only occur on New Moon, not each month because the tilt of the moon’s orbit is not in line with Earth- Penumbra: Partial shade- Umbra: Complete shadow- Partial Eclipse: Moon only covers up part of the sun (imperfect alignment)- Annular Eclipse: Perfectly aligned, but moon is too small to cover up sun. (near apogee)- Total Eclipse: Moon is large enough to cover sun. Lasts 7.5 minutes. (near
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