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Tides and Eclipses
• http://www.youtube.com/watch?v=gftT3wHJGtg
Tides• Gravity between the moon and Earth cause a
daily rise and fall in ocean waters as the moon revolves around the Earth
• Locations in line with the moon have the strongest pull and the highest tides
• As the Earth rotates, a location (labeled X) will experience high and low tides
• There are 4 tides in 24 hours, with each day having 2 high tides and 2 low tides
• Every 12 to 12.5 hours from one high tide to the next high tide OR
• 6 hours between high and low tide
• Tides are cyclic and predictable
Spring Tides
Higher than normal and lower than normal; large tidal rangeFull and new moon phase, Sun, Earth and Moon are all lined up.
Neap Tides
Little difference between high and low tides;small tidal range
First quarter and third quarter phases, Sun, Earth and Moon are at right angles
• http://www.youtube.com/watch?v=asO2wBT9W9M&feature=relmfu
Eclipses
• Umbra –
• Prenumbra -
Darkest inner part of the shadow,Will experience a total eclipse
Outer shadow, willexperience a partial eclipse
Solar Eclipse
• Sun is blocked by the Moon (Moon’s shadow falls on earth)
Can only occur in the phase New Moon
Total Solar Eclipse- July 22, 2009
NEXT TOTAL ECLIPSEIN USA
• http://www.youtube.com/watch?v=KgRuDupuRpk&feature=results_video&playnext=1&list=PL14FAB8E322C47946
LUNAR ECLIPSE• Moon is blocked by Earth’s shadow
(Earth’s shadow falls on moon)
Can only occur in the phase.Full Moon
Lunar Eclipse
Next total lunar eclipse – Sept 28, 2015
January 31, 2018
Why don’t eclipses happen every month?
Moon’s orbit is tilted at a 2-3° angle to earth’s orbit around the sun
Must align perfectly for eclipse