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