Eclipses - Solar and Lunar Eclipses

1. Lunar and Solar

2. Why don’t we see an eclipse every time
there is a full or new moon?
The Moon-Earth orbit is tilted 5 degrees with respect to the
Earth-Sun orbit.
Due to this, the Moon or Earth’s shadows will be cast above or
below the object it is eclipsing.
Only twice in its orbit will these ecliptics align so that they are
on the same plane and the possibility of an eclipse can occur,
but the moon must be full or new!

3. • Moon enters Earth’s shadow.
• Earth is always in the middle during a lunar eclipse.
• ORDER – SUN – EARTH – then MOON
A Lunar Eclipse
UMBRA: the darkest
part of a shadow
(middle of a tunnel)
PENUMBRA: the
lighter part of a
shadow (edge of a
tunnel)

4. Total Lunar Eclipse: when the moon enters the Umbra.
Partial Lunar Eclipse: when the moon enters the Penumbra.
A Lunar Eclipse

5. What are the conditions needed for visibility of a Lunar Eclipse?
A Lunar Eclipse
1. Night Side of Earth
2. Full Moon
3. Sun/Moon/Earth aligned on the same Plane

6. • The moon often looks red: light
waves bend.
• Lasts a few hours.
• Must be on the dark side of Earth
to see it.
• Occurs every 6 months.
A Lunar Eclipse
• Light refracts and
bends through Earth’s
atmosphere (like a
prism).
• The red wavelength of
light are projected onto
the moon during a total
lunar eclipse.

7. • Moon casts its shadow on Earth.
• The moon blocks the Sun!
• The moon is always in the middle.
• ORDER – SUN – MOON– then Earth
A Solar Eclipse
UMBRA: the darkest
part of a shadow
(middle of a tunnel)
PENUMBRA: the
lighter part of a
shadow (edge of a
tunnel)

8. ProminencesTotal Solar Eclipse

9. Total Solar Eclipse: when the moon’s umbra is cast on Earth.
Partial Solar Eclipse: when the moon’s penumbra is cast on Earth.
A Solar Eclipse

10. A total solar Eclipse
is only visible to
those with in the
Umbra.
A 90 mile diameter
Anyone in the
penumbra would
experience a partial
solar eclipse.
A Solar Eclipse

11. 2017Total Solar Eclipse – Interactive Map

13. What are the conditions needed for visibility of a Solar Eclipse?
A Solar Eclipse
1. Day Side of Earth
2. New Moon
3. Sun/Moon/Earth aligned on the
same Plane
4. Be in the Umbra (90 mile diameter)

14. • The sun is 400 x’s the size of the moon…BUT
• The moon is 400 X’s closer to Earth than the sun
• This cancels out the size difference and is seen as the
same size!!!
A Solar Eclipse
During a solar eclipse, the sun is blocked by the moon.
• How can the moon block such a large object like the
sun?