8/9/2019 Eclipse Summery

1/2

Carrie Adams and Sydney Pellerin

Wooten

Science: Astronomy Research Assignment

12 April 2010

Solar and Lunar Eclipses

The definition of an eclipse is only a few words, but what an eclipse really is is a spectaclethat occurs only a few times in a lifetime. A eclipse is a passage of one body through the shadow

cast by another. Eclipses happen two ways on the earth, a solar eclipse and a lunar eclipse. Though

they may sound similar enough they are actually very different from one another. In short a lunar

eclipse is the passage of the moon through the earths shadow, while a solar eclipse is an eclipse of

the sun. This happens when the moons shadow falls on the earth because it is directly in line

between the sun and the earth.

Lunar eclipse can be either total or partial. Meaning that the moon can be fully through theearths shadow or only partially. In order for a lunar eclipse to happen it needs to correctly interact

with the earths shadow. Believe it or not the earths shadow is a very complex thing made up of a

two of different parts. These two components are: a dark central umbra, and the brighter

penumbra. In the central darkest part of the shadow, the umbra, the sun in completely obscured.

The penumbra is brighter because the suns obscuration is only partial. During a lunar eclipse, the

moon first passes through the penumbra, which takes about an hour. It travels eastward in order to

reach the umbra. It takes the moon about an hour to become totally immersed in the umbra. The

umbra is not completely dark, and the moon takes on a reddish color. The maximum duration of a

lunar eclipse is 1 hour 47 minutes.

8/9/2019 Eclipse Summery

2/2

Solar eclipses are much different in many aspects. They only occur at new moons.However, eclipses of the sun do not happen every new moon because of the angle of the moon in

relation to the earth and the sun. There is a maximum amount of five solar eclipses that can happen

in one year if the lunar calender happens to be in perfect relation with everything else. In order for

a solar eclipse to occur four contacts must occur. First contact is when the east side of the moon

comes up on the suns west side. Second contact is when the eclipse really begins, in other words

the sun is completely covered by the moon. Third contact is when the first rays of sunlight show,

and the diamond ring effect occurs. Fourth contact is when the moon has parted from the sun and

the eclipse is finished. Typically in the last five minutes of the solar eclipse, the temperature drops,

and the sky becomes darker with a greenish tint. Shadow bands occur, which are moving ripples of

dark and light bands that appear on any smooth white surface. Seconds before a full eclipse, wind

drops, flower petals close, and birds roost. It also becomes noticeably cooler. The outer and inner

corona of the sun can be seen clearly. Planets and stars can be seen and the surrounding landscape

shows an orange glow. The first sign of ending totality is brightening at the moons western limb.

Eclipses can be quite beautiful things if you are able to view them correctly. There are afew ways in which you can view eclipses or just the sun without damaging your eyes. It is

important to note however, that the part of your eyes that would be damaged are the retinas. Your

retinas do not have any sensory cells so you would not be able to feel that you eyes are being

damaged until all harm is done. The retina acts as a lens in the back of our eye, almost like a

magnifying glass. The retina is then able to concentrate the light form the sun and damage your

eyes. There are a few way that the sun can be seen healthily. The most effective homemade way is

through the use of a pinhole projector. This devise consists of a long box, a piece of aluminum foil,

a pin and a white piece of paper.