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Eclipse

Subject: Science

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Overview

The moon completes one revolution around the earth in about 27.33 days (27 days, 73 hour, 43 minutes and 11.5 second). This period is called sidereal month. The time taken by the moon to come from m1 to m3 condition is called synodic month or a lunar month. Thus, the duration between two consecutive new moons is synodic month. This note provide us the information about sidereal and synodic month along with eclipse and its types.

Eclipse

The moon completes one revolution around the earth in about 27.33 days (27 days, 7 hours, 43 minutes and 11.5 seconds). This period is called sidereal month. The time taken by the moon to move from ‘m1’ to ‘m2’ condition is the sidereal month.

The time taken by the moon to come from m1 to m3 condition is called a synodic month or a lunar month. Thus, the duration between two consecutive new moons is a synodic month. Its duration is 29 days, 12 hours, 44 minutes and 3 seconds i.e. about 29.5 days.

Eclipse

The revolution of the earth around the sun and the moon around the earth sometimes cause the three heavenly bodies in the same line. It causes some or total parts of the moon or the sun invisible, that is called theeclipse.

Causes of the eclipse

  • The sun is luminous body whereas the moon and the earth are non-luminous.
  • The moon and the earth are opaque.
  • While the earth revolves around the sun and the moon around the earth, sometimes, all three masses lie in a straight line.
 

Umbra and penumbra

When a shadow is formed then the dark shadow is umbra and the light shadow is penumbra. The umbra causes total eclipse and penumbra causes the partial eclipse.

 

Solar eclipse

When the moon passes directly between the earth and the sun, it blocks the sun. It casts the shadow some part or all the part of the sun is not seen. It is called solar eclipse. A total solar eclipse occur when the sun is completely covered by the moon. It remains for 10 minutes. Total solar eclipse is important for scientist because they can study about corona of the sun in this condition. A solar eclipse stays for short period and it occurs on the new moon.

Solar eclipse
Solar eclipse
 

Lunar eclipse

When the earth passes directly between the moon and the sun. It obstructs the light of the sun. The earth casts its shadow on the moon and the moon darkens partially or completely. It is called lunar eclipse. During a Total Lunar Eclipse, the Sun, Earth and Moon form a straight line. Atotal solar eclipse stays for longer period of time i.e. 1 hour and 40 minutes. Alunareclipse occurs on the full moon only and it begins from the eastern region of the moon.

lunar eclipse
lunar eclipse
 

The nodes: RAHU and KETU.

When we study the above diagram, we find that the plane of the moon’s orbit cuts the plane of the earth’s orbit at two points. The two points are called nodes RAHU and KETU.

Things to remember
  • The moon completes one revolution around the earth in about 27.33 days (27 days, 73 hour, 43 minutes and 11.5 second). This period is called sidereal month.
  • The time taken by the moon to come from m1 to m3 condition is called synodic month or a lunar month. Thus, the duration between two consecutive new moons is synodic month.
  • The umbra causes total eclipse and penumbra causes partial eclipse.
  • When the moon passes directly between the earth and the sun, it blocks the sun. It casts the shadow some part or all the part of the sun is not seen. It is called solar eclipse.
  • When the earth passes directly between the moon and the sun. It obstructs the light of the sun. The earth casts its shadow on the moon and the moon darkens partially or completely. It is called lunar eclipse.
  • It includes every relationship which established among the people.
  • There can be more than one community in a society. Community smaller than society.
  • It is a network of social relationships which cannot see or touched.
  • common interests and common objectives are not necessary for society.
Videos for Eclipse
NASA | Lunar Eclipse Essentials
Solar Eclipse Educational Video
Questions and Answers
The moon completes one rotation around the earth in about 27 Days, 7 hours, 43 minutes and 11.5 seconds. This time taken by moon to complete one rotation is called sidereal month. The period from one new moon to another new moon or one full moon to another full moon is called synodic month. It is about 29 days.
In sidereal month, moon takes about 27 days to revolve round the earth. Similarly, in synodic month, the moon takes about 29 days to revolve round the sun. Therefore, the difference between two respective month is about 2 days and 5 hours. So, synodic month is 2 days and 5 hours longer than the sidereal month.
When the earth comes in between the sun and the moon such that all three are in a straight line, the light rays coming from sun is blocked by the earth and its shadow falls on the moon causing the lunar eclipse. Thus, lunar eclipse is the darkening of the moon when the shadow of the earth falls on the moon.
When the moon comes in between the sun and the earth such that all three are in a straight line, the light rays coming from the sun is blocked by the moon and its shadow falls on the earth. So that sun becomes invisible and causes solar eclipse. Thus, solar eclipse is the darkening of the sun when the shadow of the moon falls on the earth.
The total solar eclipse can be observed only from the place of the earth which is covered by umbra region.
The partial total solar eclipse can be observed only from the place of the earth which is covered by penumbra region.
Solar eclipse can be observed from the moon during lunar eclipse.
The moon is smaller in size. It casts narrow shadow which cannot cover all parts of the earth at the same time. The solar eclipse can be observed from the place of the earth which is covered by umbra region. Therefore, the solar eclipse cannot be seen from all parts of the earth at the same time.
Similarly, the earth is revolving around the sun and the moon is revolving around the earth. During the revolution of earth and moon, their shadows are also moving and travel from one place to another place. During the movement of shadow, lunar eclipse can be observed at the place of moon which is covered by the umbra region. Due to this region, lunar eclipse cannot be seen from all parts of the earth at the same time.
The reasons for not occurring solar and lunar eclipse in each new moon and full moon is given below:
i) The orbital plane of the sun, moon and earth do not coincide to each other.
ii) The orbital plane of the earth and moon make an angle 5.15 degree to each other.
Solar eclipse will occur in every new moon day and lunar eclipse will occur in every full moon day if the moon and the earth have the same orbital plane.
The moon revolves around the earth from west direction to east. In this process, first of all eastern part of moon enters into umbral shadows of earth. As a result, the lunar eclipse starts from the eastern part of the moon.
The rotation of the earth on its own axis from west to east is called diurnal motion.
The revolution of the earth around the sun is called annual motion of the earth.
The appearances of the moon at different stages during revolution are known as the phases of the moon.
The moon completes one rotation around the earth in about 27days. This time taken by the moon to complete one rotation is known as sidereal month. The period from one new moon to another new moon or full moon to another full moon is known as synodic month. It is about 29days.
When the earth comes in between the sun and the moon such that all three are in straight line, the light rays coming from the sun is blocked by the earth and its show falls on the moon causing the lunar eclipse. Thus lunar eclipse is the darkening of the moon when the shadow of the earth falls on the moon.
http://www.enjoyspace.com/uploads/news/juin2011/eclipse/eclipse-schema-principe-en.jpg
When the moon comes in between the sun and the earth such that all three are in straight line, the light rays coming from the sun is blocked by the moon and its show falls on the earth causing the solar eclipse. Thus solar eclipse is the darkening of the sun when the shadow of the moon falls on the earth.
The total solar eclipse can be observed only from the place on the earth which is covered by the umbra region.
The partial solar eclipse can be observed only from the place on the earth which is covered by the penumbra region.
Solar eclipse can be observed from the moon during lunar eclipse.
The moon is smaller in size. It casts narrow shadow which cannot cover all the parts of the earth at the same time. The solar eclipse can be observed from the place of the earth which is covered by umbra region. Therefore, solar eclipse is not seen from all the parts of the earth at the same time. Similarly, the earth is revolving around the sun and the moon is revolving around the earth. During the revolution of the earth and moon, their shadows are also moving and travel from one place to another place. During the movement of the shadow, lunar eclipse can be observed at the place of the moon which is covered by the umbra region. Due to this region, the lunar eclipse is not seen from all the parts of the earth at the same time.
In June 21 and December 22 in every part of the earth, there is equal day and night on earth. In this time, six months of day and six months of night are found on earth and south pole respectively. At June 21, north pole is near to the sun and on December 22, the south pole is nearer to the sun.
On 21st June, the northern hemisphere tilts towards the sun. Thus, it receives the direct sun-rays for a longer time. So, northern hemisphere has the longest day.
During total lunar eclipse, the moon is not darkened completely but it appears coppery red, it is due to the refraction of sun rays through earth's atmosphere.
The differences between synodic month and sidereal month are as follows:
Synodic month Sidereal month
The time period between any two consecutive full moon is called synodic month. The time required for one complete revolution around the earth by the moon is called sidereal month.
It has 29days. It has 27 days.
The reasons for the existence of living organism on the earth's surface sre as follows:
  1. Suitable temperature
  2. Sufficient amount of water
  3. Oxygen and carbon dioxide in the atmosphere
  4. Protective layer which protects the organisms from the UV radiation of the sun called ozone layer.
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