Earth

Shape

The shape of the Earth approximates an oblate spheroid, a sphere flattened along the axis from pole to pole such that there is a bulge around the equator.This bulge results from the rotation of the Earth, and causes the diameter at the equator to be 43 km (kilometer) larger than the pole-to-pole diameter. For this reason the furthest point on the surface from the Earth's center of mass is the Chimborazo volcano in Ecuador. The average diameter of the reference spheroid is about 12742 km, which is approximately 40,000 km/p, as the meter was originally defined as 1/10,000,000 of the distance from the equator to the North Pole through Paris, France.Local topography deviates from this idealized spheroid, although on a global scale, these deviations are small: Earth has a tolerance of about one part in about 584, or 0.17%, from the reference spheroid, which is less than the 0.22% tolerance allowed in billiard balls. The largest local deviations in the rocky surface of the Earth are Mount Everest (8,848 m above local sea level) and the Mariana Trench (10911 m below local sea level). Due to the equatorial bulge, the surface locations farthest from the center of the Earth are the summits of Mount Chimborazo in Ecuador and Huascarán in Peru.

Structure of the Earth

The interior of the Earth, like that of the other terrestrial planets, is divided into layers by their chemical or physical (rheological) properties, but unlike the other terrestrial planets, it has a distinct outer and inner core. The outer layer of the Earth is a chemically distinct silicate solid crust, which is underlain by a highly viscous solid mantle. The crust is separated from the mantle by the Mohorovicic discontinuity, and the thickness of the crust varies: averaging 6 km (kilometers) under the oceans and 30-50 km on the continents. The crust and the cold, rigid, top of the upper mantle are collectively known as the lithosphere, and it is of the lithosphere that the tectonic plates are comprised. Beneath the lithosphere is the asthenosphere, a relatively low-viscosity layer on which the lithosphere rides. Important changes in crystal structure within the mantle occur at 410 and 660 km below the surface, spanning a transition zone that separates the upper and lower mantle. Beneath the mantle, an extremely low viscosity liquid outer core lies above a solid inner core. The inner core may rotate at a slightly higher angular velocity than the remainder of the planet, advancing by 0.1–0.5° per year.

Who name EARTH ?
Mercury, Venus, Saturn, Neptune. Notice how all planets of the Milky Way are named after Gods and Goddesses of Greek and Roman Mythology?The word, Earth has Old Saxon and Germanic origins. It features an Indo-European base, “er” which in turn resulted in the natural formation of the words ertho and erde in Germanic, aarde in Dutch, and earth in English.Nobody really knows as to who came up with the name, Earth as most ancient civilizations ultimately refer to the land and soil as Earth, the planet where all humans live in. This is one of the many Earth facts which will remain hidden or unanswered for now.

Why Earth colour is Blue ?
The Earth is popularly dubbed as the Blue Planet. Astronauts who first went to space describe the entirety of Earth as blue. This is due to the fact that 71% of the planet is covered by bodies if water.

Why earth is hot ?
Aside from the sun as Earth’s main source of heat energy, humans could theoretically survive without the sun’s heat as the planet’s inner core is hot enough to supply energy to its inhabitants.
It is estimated that the core temperature is between 5,000 to 7,000 degrees Celsius. It is just as hot as the sun’s surface too!

How many space particle enter into earth atmosphere?
There are approximately 30,000 space particles and dust that enter the Earth’s atmosphere annually. Fortunately, the majority of this debris burns up when it enters the earth’s atmosphere, resulting in shooting stars instead of giant craters.

What is rotation of earth ?
We have approximately 24 hours in a day, but it is expected that after about 250 million years, a day will last 1.5 hours longer due to the slower rotation of the Earth around its axis.

How earth is moving ?
Pressure being released from the inner core and the constantly moving tectonic plates result in almost 1 million earthquakes per year; majority of which are never felt or recorded even by seismometers.

What is speed of light ?
It takes exactly about 8 minutes and 20 seconds for sunlight to reach the earth. This means that the heat and light that we see and feel on a warm, sunny day is energy emitted by the sun from 8 minutes past.
what is speed of earth rotation and Why we can not feel it ?
The Earth’s surface rotates on its axis at 1,000 miles per hour. Consequently, the planet travels through space at 66,700 miles per hour.
This is due to the fact that the Earth is rotating at a constant speed and is partly due to the gravitational pull of Earth.

Who took first photo of earth ?
From an altitude of 65 miles, the first photo of the Earth from space was taken using a 35-millimeter motion picture camera that was carried by Sputnik 2. It was in 1946 that the first discernible photo was made possible by a camera developed by the engineer, Clyde Holliday.The first full face and colored portrait of Earth was later taken from the DODGE satellite in 1967.

What is water percentage of earth ?
97% of water on Earth can be found in the oceans, while only 3% of water can be found in fresh water reservoirs and fresh water supply.

Moon

The Moon is a relatively large, terrestrial, planet-like satellite, with a diameter about one-quarter of the Earth's. It is the largest moon in the Solar System relative to the size of its planet, although Charon is larger relative to the dwarf planet Pluto. The natural satellites orbiting other planets are called "moons" after Earth's Moon.The gravitational attraction between the Earth and Moon causes tides on Earth. The same effect on the Moon has led to its tidal locking: its rotation period is the same as the time it takes to orbit the Earth. As a result, it always presents the same face to the planet. As the Moon orbits Earth, different parts of its face are illuminated by the Sun, leading to the lunar phases; the dark part of the face is separated from the light part by the solar terminator. Due to their tidal interaction, the Moon recedes from Earth at the rate of approximately 38 mm a year. Over millions of years, these tiny modifications—and the lengthening of Earth's day by about 23 µs a year—add up to significant changes.During the Devonian period, for example, (approximately 410 mya) there were 400 days in a year, with each day lasting 21.8 hours.The Moon may have dramatically affected the development of life by moderating the planet's climate. Paleontological evidence and computer simulations show that Earth's axial tilt is stabilized by tidal interactions with the Moon.Some theorists believe that without this stabilization against the torques applied by the Sun and planets to the Earth's equatorial bulge, the rotational axis might be chaotically unstable, exhibiting chaotic changes over millions of years, as appears to be the case for Mars.Viewed from Earth, the Moon is just far enough away to have almost the same apparent-sized disk as the Sun. The angular size (or solid angle) of these two bodies match because, although the Sun's diameter is about 400 times as large as the Moon's, it is also 400 times more distant.This allows total and annular solar eclipses to occur on Earth.The most widely accepted theory of the Moon's origin, the giant impact theory, states that it formed from the collision of a Mars-size protoplanet called Theia with the early Earth. This hypothesis explains (among other things) the Moon's relative lack of iron and volatile elements, and the fact that its composition is nearly identical to that of the Earth's crust.