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Q. 3. Complete the following table.
Details Lunar Eclipse
e sun.
Solar
Eclipse
New moon
day
on, the
Phase of the
ned in
moon
Sequence
earth
lane.
Moon-Earth-
Sun
7, its
Type of
only
107 minutes
eclipse
Maximum
duration of
total eclipse
ipse
Answers
Lunar Eclipses
Moon passes through the Earth's shadow
Total, Partial, & Penumbral lunar eclipses
Solar Eclipses
Earth passes through the Moon's shadow
Total, Partial, & Annular solar eclipses
The Eclipse Year
How often do eclipses occur?
Umbra and Penumbra
Because the Sun appears as a disk ~1/2° across, Sun shadows are fuzzy rather than sharp.
This means shadows cast by the Earth & Moon are two-part shadows:
(Click on the image to view at full scale [Size: 10Kb])
Umbra: Inner core of total darkness
The disc of the Sun is completely blocked.
Penumbra: Outer, partial shadow
Sun's disc is only partly blocked, with a bit peeking over the edge.
Lunar Eclipses
Lunar Eclipses occur when the Moon passes through the shadow of the Earth.
They only occur during Full Moon when the Earth is between the Moon and the Sun.
The Earth's umbra is ~1.4 Million km long:
About 3.7x the mean Earth-Moon distance.
Umbra's width is 9000 km at the distance of the Moon, or ~2.6x the Moon's diameter.
The Earth's umbra is not totally dark because of light scattered by the Earth's transparent atmosphere. This gives the fully eclipsed Moon a slightly ruddy appearance (think about how the Sun looks reddish at sunset or sunrise).
Three Types of Lunar Eclipses
(Click on the image to view at full scale [Size: 10Kb])
Total Lunar Eclipse:
Entire Moon is within the Earth's umbra.
Can spend up to 1h 40m in the umbra
Whole show can last ~6 hours
Partial Lunar Eclipse:
Only part of the Moon enters the umbra.
Penumbral Eclipse:
Moon misses the umbra completely, only passes through the penumbral shadow.
Because the Moon can be completely immersed in the Earth's umbra during a total lunar eclipse, these eclipses can be seen from the entire night-time hemisphere. This is in contrast to total solar eclipses as we'll see below.
Solar Eclipses
Solar Eclipses occur when the Earth passes through the shadow of the Moon.
Solar Eclipses only occur during New Moon, when the Moon is between the Earth and the Sun.
The Moon's umbra is only 380,000 km long:
Just long enough for the tip to touch the Earth.
But not large enough to cover the entire Earth.
Solar Eclipses can be seen only where the shadow passes overhead.
Types of Solar Eclipses
(Click on the image to view at full scale [Size: 10Kb])
Total Solar Eclipse:
The observer is inside the Moon's umbra.
The Moon completely covers the Sun.
Partial Solar Eclipse:
The observer is inside the Moon's penumbra.
Only see part of the Sun covered by the Moon.
Annular Eclipse:
The Moon is at or near apogee, and so is too small to cover the Sun.
The Moon's umbra does not touch the Earth, so observer's in the shadow path see the Sun as a ring ("annulus").