cycles of the sky chapter 3:. a total lunar eclipse (ii) a total lunar eclipse can last up to 1 hour...
Post on 20-Dec-2015
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A Total Lunar Eclipse (II)
A total lunar eclipse can last up to 1 hour and 40
min.
During a total eclipse, the moon
has a faint, red glow, reflecting
sun light scattered in the Earth’s atmosphere.
Solar Eclipses (I)
The angular diameter of the moon (~ 0.5o) is almost exactly the same as that of the sun.
This is a pure chance coincidence. The moon’s linear diameter is much smaller than that of the sun.
Total Solar Eclipse
The moon’s shadow sweeps across the Earth, over points
from where we can see a solar eclipse.
Total Solar Eclipse
During a total solar eclipse, the solar chromosphere, corona, and prominences
can be seen.
Earth’s and Moon’s orbits are slightly elliptical:
Sun
Earth
Moon
(Eccentricities greatly exaggerated!)
Perihelion = position closest to the sun
Aphelion = position furthest
away from the sun
Perigee = position closest to Earth
Apogee = position furthest away from
Earth
Annular Solar EclipsesThe angular sizes of the Moon and
the Sun vary, depending on their distance
from Earth.
When the Earth is near perihelion, and the Moon is
near apogee, we see an annular solar eclipse.
Perigee Apogee Perihelion Aphelion
Very Important Warning:Never observe the sun directly with your bare eyes,
not even during a partial solar eclipse!
Use specially designed solar
viewing shades, solar filters, or a
projection technique.
Conditions for Eclipses (I)
The Moon’s orbit is inclined against the ecliptic by ~ 50.
A solar eclipse can only occur if the Moon passes a node near New Moon.
A lunar eclipse can only occur if the Moon passes a node near Full Moon.