Atmosphere

The Earth's atmosphere has no definite edge, slowly becoming thinner and vanishing into outer space. Three-quarters of the atmosphere's mass is contained within the first 11 km of the planet's surface. This lowest coating is called the troposphere. Further up, the atmosphere is usually separated into the stratosphere, mesosphere, and thermosphere. Away from these, the exosphere thins out into the magnetosphere. A vital part of the atmosphere for life on ground is the ozone layer.

The atmospheric stress on the surface of the Earth averages 101.325 kPa, with a scale height of about 6 km. It is 78% nitrogen and 21% oxygen, with trace amounts of other gaseous molecules such as water steam. The atmosphere protects the Earth’s life forms by captivating ultraviolet solar emission, moderating temperature, transporting water vapor, and provides useful gases. The atmosphere is one of the principal mechanism in determining weather and climate.

Because hydrogen gas is light and based on Earth's signify temperature, achieves break out velocity, unfixed hydrogen leaves the Earth. For this cause, the Earth's environment is oxidizing, with consequences for the chemical nature of life which developed on the planet.

Giza pyramid complex

The Giza Necropolis stands on the Giza Plateau, on the outskirts of Cairo, Egypt. This complex of ancient monuments is located some eight km inland into the desert from the old town of Giza on the Nile, some 20 km southwest of Cairo city centre.

Speed through space

In the general sense, the absolute speed of any object through space is not a meaningful question according to Einstein's Special Theory of Relativity, which declares that there is no "preferred" inertial frame of reference in space with which to compare the galaxy's motion. With this in mind, many astronomers believe the galaxy is moving through space at approximately 600km per second relative to the observed locations of other nearby galaxies. Most recent estimates range from 130 km/s to 1,000 km/s. If indeed the Milky Way is moving at 600 km per second, we are travelling 51.84 million km per day, or more than 18.9 billion km per year. For comparison, this would mean that each year, we are travelling about 4.5 times the distance that Pluto lies from the Earth. The Milky Way is thought to be moving in the direction of the constellation Hydra, and may someday become a close-knit member of the Virgo cluster of galaxies. Our galaxy may also collide with the Andromeda galaxy in roughly 4 billion years. See below.