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Lunar Eclipse Chapter 3 from book

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Page 1: 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

Lunar Eclipse

Chapter 3 from book

Page 2: 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

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.

Page 3: 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

Starter

• http://www.space.com/22852-fall-equinox-earth-seasons-explained.html

• Fall equinox on September 22 - Sunday

Page 4: 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

Lunar Eclipse

• http://www.youtube.com/watch?v=wuhNZejHeBg

• This is a brief video from NASA explaining how a lunar eclipse works.

Page 5: 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

Lunar Eclipse

Take note of the

components of Earth’s

shadow, the umbra and penumbra

and the role they play in

the lunar eclipse

Page 6: 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

Lunar Eclipse

• Moon is tipped only a few degrees from the plane of Earth’s orbit around the sun.

• Earth’s shadow points directly away from the sun (also on the plane of Earth’s orbit)\

• Thus a lunar eclipse is when the Moon’s path is carries it directly through the shadow of the Earth.

Page 7: 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

Umbra

• This is the region of total shadow• From the book:– If you were drifting in your space suit in the umbra

of Earth’s shadow, the sun would be completely hidden behind Earth.

Page 8: 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

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.

Page 9: 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

At the Height of an Eclipse – in the Umbra

Page 10: 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

Lunar Eclipse

• Generally most full moons pass north or south of Earth’s 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.

Page 11: 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

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.

Page 12: 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

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 Earth’s 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.

Page 13: 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

Total Lunar Eclipse

• An eclipse can last for as much as 1 hour 45 minutes.

• http://www.youtube.com/watch?v=lcRp1jKJmJU

• You Tube video of a “speeded up” lunar eclipse.

Page 14: 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

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 Earth’s umbral shadow?

4. If a lunar eclipse occurred at midnight, where in the sky would you look to see it?