General Awareness Earth

The Earth

`color{green} ul{"The Earth"}`

`color{green} ✍️` The Earth is a unique planet. It is the third planet from the Sun and the densest as well as the fifth-largest of the eight planets in the solar system. It is the largest of the solar system's four terrestrial planets also known as Blue Planet.

It is small and rocky and as far as we know, the only planet that has life on it. About three quarters of the Earth's surface is covered with water and it is the only planet on which water can exist in liquid form on the surface. This is the reason that life can be sustained on it. The Earth is about 4.5 - 4.6 billion years old. It is orbited by one moon.

Tilt of the Earth's Axis

`color{purple}ul{"Tilt of the Earth's Axis"}`

`color{green} ✍️` The axis of the Earth is inclined to the plane of ecliptic (the plane, in which the Earth orbits round the Sun) at an angle of `661/2` giving rise to different seasons and varying lengths of day and night.

`color{green} ✍️` If the axis were perpendicular to this plane, all parts of the globe would have equal days and nights at all times of the year.

`color{green} ✍️` The Earth is tilted about "23.5" from a line perpendicular to ecliptic plane.

Equinox

`color{purple}ul{"Equinox"}`

`color{green} ✍️` These are the days, when days and nights are equal. Under this situation, the Sun is vertically overhead at the equator. It. happens on two days of the year i.e. 21st March Vernal Equinox and 23rd September Autumnal Equinox.

Summer Solstice

`color{purple}ul{"Summer Solstice"}`

`color{green} ✍️` After the March equinox, the Sun appears to move northward and is vertically overhead at the Topic of Cancer on 21st June. This is known as summer solstice. In it, the Northern Hemisphere will have its longest day and shortest night. The Southern Hemisphere will have shortest day.

Winter Solstice

`color{purple}ul{"Winter Solstice"}`

`color{green} ✍️` By 22nd December, the Sun is overhead at the Tropic of Capricorn. This is the Winter Solstice, when the Southern hemisphere will have its longest day and shortest night.

Revolution of Earth

`color{purple}ul{"Revolution of Earth"}`

`color{green} ✍️` It is the Earth's motion in elliptical orbit around the Sun. It takes 365 days, 5 hours, 48 minutes and 45.51 seconds. It leads to one extra day in every fourth year. The revolution of Earth results in
1. Changes of season
2. Variation of the length of the days and nights at different times of the year
3. Shifting of the wind belts

Rotation of Earth

`color{purple}ul{"Rotation of Earth"}`

`color{green} ✍️` The Earth spins on its imaginary axis from West to East in 23 hr, 56 min and 40.91 sec.

`color{green} ✍️` The rotational speed at equator is maximum (1667 km/hr) and then decreases towards the poles, where it is zero. The days and the nights are equal at the equator.

`color{green} ✍️` The rotation of the Earth has the following implications such as
1. Causation of day and night.
2. Change in the direction of winds and ocean currents.
3. Rise and fall of tides everyday.
4. A difference of one hour between the two meridians, which are 15 apart.

Seasons

`color{purple}ul{"Seasons"}`

`color{green} ✍️` They are the periods into which the year can be divided as a result of the climatic conditions, mainly due to the changes in duration and intensity of solar radiation.

`color{green} ✍️` The imaginary surface on which Earth orbits around the Sun is called as the plane of ecliptic. The Earth axis is inclined `65` degree to the plane of the ecliptic as `23.5` degree from the perpendicular to the plane of the ecliptic. The Earth maintains its orientation with respect to the stars. Thus, the North pole points in the same direction to polar is and the North Star, as it revolves about the Sun.

There are four seasons which are :
1. autumn
2. spring
3. summer and
4. winter.


Autumn – The earth moves so it is no longer tilted towards the sun. There is less heat and light, so days get shorter and cooler. Plants start to lose their leaves and dry up.

Spring– The earth moves so it is no longer tilted away from the sun. There is more heat and light, so days get longer and warmer. Plants start to grow, flowers bloom, and snow melts away!

Summer – In the summer, the north is tilted towards the sun and gets the most heat and sunlight. This makes the days longest and hottest, and helps plants to grow.


Winter – In the winter, the north part of the earth tilts away from the sun. It receives the least amount of light and heat, so days in winter are short and cold. Snow falls and water can freeze to ice.



Eclipses

`color{purple}ul{"Eclipses"}`

`color{green} ✍️` An eclipse occurs, when the Sun, Moon and Earth are in a straight line.

`color{green} ✍️` There are two types of eclipses-Solar and Lunar eclipse.

Difference Between Lunar and Solar Eclipses

There Are Two Basic Types Of `color{blue}ul{"Eclipses "}`

`->` Solar Eclipse
`->` Lunar Eclipse


`color{blue}{"Solar Eclipse"}`

`color{blue}►` An eclipse of the Sun, or a solar eclipse, is when the Moon is between the Sun and Earth. and Only occurs when the Moon is at just the right distance and angle in the sky to cover the Sun.

`color{blue}►` This can only occur when the Sun, Moon and Earth are exactly aligned producing a Total Solar Eclipse.

`color{blue}►` The Moon also has to be at or near one of its nodes; a node is simply the point at which the Moon crosses the eliptic from south to north or vice versa as it orbits the Earth.

`color{blue}►` A Total Solar Eclipse occurs during daytime and only when there is a New Moon.

`color{blue}►` A solar eclipse duration is short with totality lasting from a few secounds to a few minutes.

`color{blue}►` A Total Solar Eclipse is only seen by a minority of people along a narrow corridor and appears different according to ones location and distance from the central track of totality.

`color{blue}{"Lunar Eclipse"}`

`color{blue}►`An eclipse of the Moon, or lunar eclipse, is when the Earth is between the Sun and Moon.

`color{blue}►`Its only occurs if the Moon passes through all or some portion of Earth's umbra shadow therefore blocking sunlight directly striking the Moon’s surface.

`color{blue}►`This can occur only when the Sun, Earth, and Moon are aligned exactly, or almost exactly.

`color{blue}►`A lunar eclipse occurs at night and only when there is a Full Moon. A lunar eclipse can last for many hours, and can be seen from the entire night side of the Earth.

International Date Line

`color{purple}ul{"International Date Line"}`

`color{green} ✍️ ` It is the 180 meridian running over the Pacific Ocean, deviating at Aleutian Island, Samoa and Gilbert Island.

`color{green} ✍️ ` This is the International Date Line, where the date changes by exactly one day when it is crossed.

`color{green} ✍️ ` Samoa and Token shifted their position back to West of the Date line on 30th December, 2011.

Structure of Earth's Interior

`color{purple}ul{"Structure of Earth's Interior"}`

The layer of the interior of Earth is divided into three pints
1. Crust
2. Mantle
3. Core

 
SiteLock