Presentation on theme: "Geometry: Sun – Moon– Earth"— Presentation transcript:
1Geometry: Sun – Moon– Earth EclipsesEclipses are named after the object that “disappears”Lunar eclipse:Moon “disappears”Geometry: Sun – Earth – MoonSolar eclipse:Sun “disappears”Geometry: Sun – Moon– Earth
2Lunar EclipsesLunar eclipses occur when the Moon enters the shadow of the EarthThe Earth’s shadow has 2 parts:Umbra – all sunlight blockedPenumbra – only some sunlight blocked3 types of lunar eclipses:Total – all of Moon in umbraPartial – only part of Moon in umbraPenumbral – Moon only in penumbra
3TPS Question Who can see Lunar Eclipses? Anyone on Earth’s day side Anyone on Earth’s night sideAnyone near the Earth’s equatorAnyone at all
6Solar EclipsesSolar eclipses occur when the Earth enters the shadow of the Moon (the Moon blocks the Sun).Moon and the Sun have approximately the same (apparent) angular size (1/2 degree).Sometimes the Moon doesn’t cover the whole Sun and we get an annular eclipse.
7The Moon’s shadow also has 2 parts: Umbra – all sunlight blockedPenumbra – only some sunlight blocked3 types of lunar eclipses:Total – Sun completely covered by MoonPartial – Only part of the Sun covered by MoonAnnular – Some sunlight gets around edge of Moon
8TPS Question Who can see total Solar Eclipses? Anyone on Earth’s night sideAnyone on Earth’s day sideAnyone near the Earth’s equatorOnly people along a certain path
22TidesGravity: The Moon pulls more on the near side of the Earth than the far side.
23TidesAs a result, water in the oceans is at “high tide” twice a day. Once on the near side to the Moon and again on the far side from the Moon.
24TPS Questionnew moonfull moonthird quarter moonboth new and full moonAt what lunar phase would the variation between high & low tides be greatest?
25TPS Questionnew moonfull moonthird quarter moonboth new and full moonAt what lunar phase would the tidal variation be greatest?At new & full moon phases, the Sun and Moon combine to stretch the Earth and its oceans even more. We see higher high tides and lower low tides.
26Spring and Neap TidesThe Sun can also cause tides, but only half as strong as the Moon.Spring tide – when the tides from the Sun and the Moon combineNeap tide – when the tides from the Sun and the Moon counter-act each other.
27Spring and Neap TidesThe Sun has less effect, but it does modify the lunar tides:
28Synchronous Rotation The Moon’s near side is always towards the Earth. Moon has become tidally locked to the Earth.