Eclipses and Terminology · 2019. 8. 22. · Objectives: S.W.B.A.T. Explain how solar and lunar...
Transcript of Eclipses and Terminology · 2019. 8. 22. · Objectives: S.W.B.A.T. Explain how solar and lunar...
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Objectives: S.W.B.A.T.
Explain how solar and lunar eclipses occur
Define: earthshine, limb, terminator, unbra,
penumbra
Name several things that occur during an eclipse
and the conditions needed to have an eclipse of
the sun and oe moon
Draw the 3 types of eclipses
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Activities:
Warm-up
Notes/discussion
Diagram model drawings
Video clips of eclipses animations plus
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Eclipses and Terminology
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Earthshine – the reflection and refraction
properties of our atmosphere causes the moon’s
unlighted portion to be visible. (can easily be
viewed during crescent phases and lunar
eclipses)
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Terminator – line between the lighted and dark
part of a celestial object. (best area to view
features on the moon – good contrast)
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Limb – outer edge view of a celestial object.
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Eclipse – when an object passes within the
shadow of another.
When an object casting a shadow is close to the
source of light (non-point source) two shadows
appear.
Umbra – dark inner shadow (total eclipse)
Penumbra – light outer shadow (partial eclipse)
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Total Solar Eclipse – moon blocks out the sun,
line up is sun-moon-Earth
Next date(s): _______________________
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Conditions needed:
moon must be 383,000 km or closer (near perigee)
must be at a node on its orbit (where the moon
orbital plane intersects with the ecliptic. Moon’s
orbit lies 5.2° above or below ecliptic path.
person observing must be in umbra shadow – 300
km wide
phase of the moon is New lined up known as
Syzygy- is the lining up of any 3 celestial objects
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Events and time: Time of totality will never be more than 7 ½ minutes
of total blocking of sun’s photosphere.
Corona can be see (outermost part of the sun’s
atmosphere)
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Diamond ring effect and Bailey’s beads (sunlight
from photosphere shines through craters and
valleys just prior and ending of totality.
Dogs howl, chickens roost, birds cease singing,
flowers close, and temp. cools ground takes on a
strange hue of colors.
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Annular (ring) Eclipse – occurs when the same
conditions for a solar eclipse are met except the
umbra shadow of the moon does not reach the
Earth. Moon is greater than 383,000 km.
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Objectives: S.W.B.A.T.
Explain and draw diagram comparing lunar &
solar eclipses
Define: umbra, penumbra, terminator, limb
Explain why eclipses do not occur every month
Discuss events and occurrences that happen
during eclipses
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Activities:
Warm-up
Notes/discussion
Complete any outstanding work – due
Work on constellation cards
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Lunar Eclipse – Earth blocks out moons light or
Earth’s shadow covers moon. Sun-Earth-moon
Conditions needed:
full moon – syzygy
moon must be at a node
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Events and time:
Last several hours due to the fact Earth’s shadow is
much larger. Moon never gets completely dark or
obscured due to the refraction and reflection
properties of our atmosphere (earthshine). Moon
takes on a copper reddish hue.
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Eclipse season – Times during the year when the
moon lies in the same plane as the Earth and
sun, so that eclipses are possible. Occurs six
months apart when moon is on a node. One
would expect a solar eclipse to be followed by a
lunar eclipse.
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A cycle of eclipses is 346.6 days – eclipse year it
progresses gradually backward in the calendar
occurring 19 days earlier each day. Regression of nodes
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Calculations show that every 6585 solar days or 18
years. 11.3 days the same position in the sky an eclipse
would occur. This is called a Saros cycle
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Video clips animations show
http://eclipsegeeks.com/default.aspx
http://eclipsegeeks.com/default.aspx