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Shadows

Shadows. Shadows. Shadows- areas light cannot reach due to an opaque object in light’s path. There are two parts to a shadow. Umbra- sharp black center of a shadow Penumbra- fuzzy gray outer portion of the shadow. Shadow. Penumbra. Umbra. These shadows cause eclipses.

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Shadows

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  1. Shadows

  2. Shadows • Shadows- areas light cannot reach due to an opaque object in light’s path. • There are two parts to a shadow. • Umbra- sharp black center of a shadow • Penumbra- fuzzy gray outer portion of the shadow

  3. Shadow Penumbra Umbra

  4. These shadows cause eclipses • When the Earths shadow falls on the moon you get a lunar eclipse. • When the Moons shadow falls on the Earth you get a solar eclipse. • If you are in the umbra you will see a total eclipse. • If you are in the penumbra you will see a partial eclipse. • http://www.forgefx.com/casestudies/prenticehall/ph/eclipse/eclipses.htm

  5. Solar Eclipse *This is not to scale

  6. Not to Scale… • These drawings are not to scale. • Here is a picture showing the actual size of the Sun compared to the Earth and Moon.

  7. Actual size of Astronomical Objects • http://sciencenetlinks.com/interactives/messenger/psc/PlanetSize.html

  8. ?!?!?! • How can the Moon block out such a large object? • The Moon is on average 385,000 km from Earth. • The Sun is on average 1,500,000 km from Earth, or almost 400x further away. • In our sky, both objects appear to be almost the same size. • http://phet.colorado.edu/sims/gravity-and-orbits/gravity-and-orbits_en.jnlp

  9. Homework • Read sections 25.5 and 25.6 • Pg 549 • Questions 16-19; 26, 28-30, 42, 44, 45

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