Our Moon
Moon Orbits the Earth – but appears to rise in the east and set in the west due to earth’s faster rotation 13 ° a day rotation of moon compared to 15° per hour of earth --- earth rotates faster than the moon revolves around the earth
Moon’s Rotation = Moon Revolution rotation period = 27.3 days revolution period = 27.3 days Moon shows the same “face” to the Earth Velocity: 360°/27.3 days = 13° per day
Daily Movement of the Moon Each day the Moon rises in the east and sets in the west as a result of the Earth's rotation. It moves about 13° eastwards against the background of stars as a consequence of its revolution around the Earth.
Moon Phases Half of the moon is always receiving light from the sun. The “lit” portion that is visible to earth varies as the moon REVOLVES around earth. THIS CAUSES THE PHASES OF THE MOON. Visible portion of moon growing = waxing Visible portion of moon shrinking = waning
Lunar Phases
Cycle of Lunar Phases Takes 29.53 days This is because when moon gets back to its original position in 27.3 days, the earth has moved 1°/day or about 27°. The moon moving at l3°/day takes about 2 days to catch up with Earth and align with it and the sun in a new moon phase. The moon rises above the horizon at a different time each day (or night). This happens because every time Earth spins around once, the moon moves about l3° eastward along its orbit. The earth must rotate an extra l3 deg. More each day for a point on its surface to be roughly under the moon again. Earth takes 50 minutes to spin 13 deg., the moon rises about 50 minutes later each day and sets about 50 minutes later as well.
Lunar and Solar Eclipses The Moon orbits the Earth, and travels with the Earth about the Sun. Sometimes the Moon gets between the Earth and the Sun, causing solar eclipses, and sometimes the Moon goes into the Earth's shadow, causing lunar eclipses.
Solar Eclipses – can occur only during the new moon phase Lunar eclipses – can occur only during the full moon phase
The Cause of Eclipses: Shadows
Lunar Eclipses
Solar Eclipses
Solar Eclipses Occur when moon’s orbit intersects ecliptic during the new moon phase