The document discusses why the moon appears red during a lunar eclipse. It explains that during a lunar eclipse, the moon passes through the Earth's shadow. Red light from the edges of the Earth is able to pass through the atmosphere and illuminate the moon, giving it a red appearance. The atmosphere scatters blue light more than red light due to Rayleigh scattering, so the light that reaches the moon during an eclipse is dominated by red wavelengths.

1. 4/16/2020 1Prem Kumar Soni

2. 4/16/2020Prem Kumar Soni 2

3.  A total lunar eclipse is sometimes called a
Blood Moon, because of the reddish tinge
the Full Moon takes on when fully eclipsed.
The term is also frequently used to describe
four total lunar eclipses that occur in a row.
4/16/2020 3Prem Kumar Soni

4. When the moon passes through the
middle of Earth's shadow, red
light from the fringes around Earth
beam onto the surface of the moon,
turning it red.
4/16/2020 4Prem Kumar Soni

5. Sunlight is made of different colors of light
with different intensity for each color,
combined together.
White light is made of all the colors in equal
intensity.
Light passes a long distance through the
atmosphere in this direction, and the gases in
the atmosphere let the red light pass through
4/16/2020 5Prem Kumar Soni

6. It happens that our atmosphere scatters blue light more than
red.
This is called "Rayleigh's scattering".
Therefore out of all the colors in the sunlight, blue light is
the
one that is scattered and reaches our eyes during the day.
During a lunar eclipse, the moon turns red.
A lunar eclipse is when moon, earth and
sun align in a straight line with the earth in between the
sun and the moon
When this happens, light from the sun first hits the earth.
4/16/2020 6Prem Kumar Soni

7. 4/16/2020Prem Kumar Soni 7

8. When fight encounters molecules in the air, the
predominant mode of
scattering is elastic scattering, called Rayleigh
scattering.
This scattering is responsible
for the blue color of the sky; it increases with the
fourth power of the frequency and is
more effective at short wavelengths.
4/16/2020 8Prem Kumar Soni

9. It is also possible for the incident photons to
interact with the molecules in such a way
that energy is either gained or lost so that the
scattered photons are shifted in frequency.
Such inelastic scattering is called Raman scattering.
4/16/2020 9Prem Kumar Soni

10. 4/16/2020Prem Kumar Soni 10