The Motion of the Moon The Moon The Earth, Sun, and Time of Day

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Astronomy 310 (Newbury) May 15, 2007 Why is the lunar eclipse red The Moon may be directly behind the Earth, but it is not completely dark because the Earth’s __________ bends the sunlight onto the Moon: refraction Sure, but why is it ___ The Earth’s atmosphere also scatters away shorter wavelength light (blue) leaving the _____ wavelengths (red) to travel on to the Moon. red and blue mixed blue red Next Lunar Eclipse The length of time the Moon spends eclipsed by the Earth depends on its _____through the umbra. It can last for up to 1:47 hours. The next total lunar eclipse is on August 28. We should be able to ______ the whole event from here in Vancouver. This is a long-exposure picture that shows the fainter, redder light during the eclipse. 29 Espenak (Mr. Eclipse) 30 If the full Moon passes partly through the umbra, it is only ________ blocked. Partial Lunar Eclipse The portion of the Moon in the umbra may turn quite dark (or red). The portion only in the penumbra may still be _____, though, producing a partial lunar eclipse. How Good is the Alignment, Anyway Imagine making a scale model of a lunar eclipse. The important quantities are: Quantity Length (km) Scale to Moon pinky fingernail Moon diameter 3475 1 1 cm Earth diameter 12 756 3.67 3.67 cm Sun diameter 1 392 530 400.7 400 cm (____) Earth-Moon distance 384 400 110.6 111 cm (1.1 m) Earth-Sun distance 149 600 000 43 050 __________ (______ m) 1 392 530 = 400.7 3475 31 32 8
Astronomy 310 (Newbury) May 15, 2007 How Good is the Alignment, Anyway Quantity Scale to Moon head of a pin Moon diameter 1 1 mm Earth diameter 3.67 3.67 mm Sun diameter 400.7 400 mm (40 cm) Earth-Moon distance 110.6 111 mm (1.1 cm) Earth-Sun distance 43 050 43 050 mm (43 m) model Hold the head of the pin 1.1 cm from the head of the quilt pin. Hold them so they line up with the Sun circle across/down the hall! Question How good is the alignment, anyway unbelievable! I can’t believe it ever happens! no wonder lunar eclipses are rare! Geez, I couldn’t even do it! 33 34 Solar Eclipses The Moon’s Shadow Lunar eclipses occur when the Moon passes into the shadow of the Earth. _____ eclipses occur when the ______ passes into the shadow of the Moon. solar corona prominences (Espenak) By remarkable chance, the Moon is just the right size and distance from the Sun to almost perfectly block out the Sun’s disk, revealing features normally ________ in the brightness of the Sun. 35 The shadow of the Moon also has a umbra and penumbra region. The “tip” of the umbra just barely ________________ of the Earth, “painting” a dark circle on the ground that races along the __________at over 1700 km/h. A solar eclipse never lasts longer than 7½ minutes at any location (and usually it’s a lot less!) 36 9
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The Motion of the Moon The Moon The Earth, Sun, and Time of Day

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