Presentation on theme: "Lunar Eclipse Chapter 3 from book. Objectives To be able to describe the phenomenon of how a lunar eclipse occurs. To be able to apply what they already."— Presentation transcript:
Lunar Eclipse Chapter 3 from book
Objectives To be able to describe the phenomenon of how a lunar eclipse occurs. To be able to apply what they already know about the moons orbit to this special case. To apply what they know about the wavelengths of light to the appearance of the moon during the eclipse.
Starter http://www.space.com/22852-fall-equinox- earth-seasons-explained.html http://www.space.com/22852-fall-equinox- earth-seasons-explained.html Fall equinox on September 22 - Sunday
Lunar Eclipse http://www.youtube.com/watch?v=wuhNZejH eBg http://www.youtube.com/watch?v=wuhNZejH eBg This is a brief video from NASA explaining how a lunar eclipse works.
Lunar Eclipse Take note of the components of Earths shadow, the umbra and penumbra and the role they play in the lunar eclipse
Lunar Eclipse Moon is tipped only a few degrees from the plane of Earths orbit around the sun. Earths shadow points directly away from the sun (also on the plane of Earths orbit)\ Thus a lunar eclipse is when the Moons path is carries it directly through the shadow of the Earth.
Umbra This is the region of total shadow From the book: – If you were drifting in your space suit in the umbra of Earths shadow, the sun would be completely hidden behind Earth.
Penumbra Again, if you are drifting in your space suit: – In the penumbra, you would see part of the sun peeking around the edge of Earth. – You would be in partial shadow. – Sunlight is dimmed but not extinguished like in the umbra.
At the Height of an Eclipse – in the Umbra
Lunar Eclipse Generally most full moons pass north or south of Earths shadow and there is no eclipse. There are partial eclipses and total eclipses. Partial Eclipse – When the moon passes a bit too far north or south of Earth, it may only partially enter the umbra. – Usually cannot see the coppery glow.
Total Lunar Eclipse During a total eclipse, the moon moves into the penumbra where it dims slightly. – As it moves, the dimming increases. Finally it reaches the umbra where the moon begins to darken as it slides into the umbra. When it is totally eclipsed, the moon does not disappear.
Total Lunar Eclipse The moon does not receive direct sunlight but light waves in the red spectrum are bent around Earth. – They pass through the Earths atmosphere. – Blue light, much shorter wavelength, is scattered as it hits the atmosphere (which is why the sky is blue). – Red light continues on and does reach the moon, creating its reddish glow.
Total Lunar Eclipse An eclipse can last for as much as 1 hour 45 minutes. http://www.youtube.com/watch?v=lcRp1jKJm JU http://www.youtube.com/watch?v=lcRp1jKJm JU You Tube video of a speeded up lunar eclipse.
Review 1.Which lunar phases would be visible in the sky at dawn? At midnight? 2.Looking back at Earth from the moon, what phase would Earth have when the moon was full? 3.Could a solar-powered spacecraft generate any electricity while passing through Earths umbral shadow? 4.If a lunar eclipse occurred at midnight, where in the sky would you look to see it?