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

Activities:

Warm-up

Notes/discussion

Diagram model drawings

Video clips of eclipses animations plus

Eclipses and Terminology

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)

Terminator – line between the lighted and dark

part of a celestial object. (best area to view

features on the moon – good contrast)

Limb – outer edge view of a celestial object.

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)

Total Solar Eclipse – moon blocks out the sun,

line up is sun-moon-Earth

Next date(s): _______________________

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

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)

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.

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.

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

Activities:

Warm-up

Notes/discussion

Complete any outstanding work – due

Work on constellation cards

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

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.

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.

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

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

Video clips animations show

http://eclipsegeeks.com/default.aspx

http://eclipsegeeks.com/default.aspx