Milky Way (Aakaash Ganga):
When we explore our planet Earth from the outer space we come across a galaxy of stars which look like a gigantic whirlpool. This galaxy is known as the Milky Way or in our own language Aakaash Ganga.
Formation of Earth
According to scientists, a huge spinning cloud of gas and dust is responsible for the formation of the Sun and the solar system of which the Earth is one planet. Most of the gas and dust was pulled due to force of gravity and formed the Sun. While the remaining gas and dust formed the Earth and the other planets of the solar system. It is believed that the Earth is formed about 4.6 billion years ago (1 billion = 10,000 Lakhs).
Inside the Earth
The Earth is made of three layers - the crust, the mantle and the core. The top layer is called the crust and is made of hard rocks and soil. More than 70 % of Earth's crust is covered with water in the form of oceans, seas, lakes and the like. The part of Earth's crust that is under the oceans is known as the ocean floor or sea floor.
The layer beneath the crust is called the mantle which is made of partly melted rocks. Under the mantle is the innermost layer of the Earth called the core which is mostly iron. The outer part of the core is made of liquid metal and the inside of the core is made of solid metal. As per scientists it is because of this liquid metal the Earth is acting like a giant magnet creating the Earth's magnetic field.
Life on Earth
Earth is neither too hot nor too cold and it has the right conditions that help in supporting life. The water on the Earth and the envelope of atmosphere consisting of various gases are the main conditions that support life on Earth.
Revolution of the Earth and seasons
The Earth revolves round the Sun in its own orbit and it takes 365 days and 6 hours for the Earth to complete one revolution. There is an imaginary line that runs from the North pole to the South pole is called the axis of the Earth. Seasons are caused on the Earth due to the tilted axis of the Earth. Similarly the imaginary line that runs around the mid of the Earth is called the Equator which divides the Earth into two equal halves. The upper half is called the Northern hemisphere and the lower half is called the Southern hemisphere. When the Northern hemisphere is tilted towards the sun, the land in this hemisphere experiences summer season. And at the same time as the Southern hemisphere will be tilted away from the sun, the land in this hemisphere experiences winter season. In the same manner, when it is winter in the Northern hemisphere it will be summer in the Southern hemisphere. And when these hemispheres are not tipped towards the sun, these will experience spring season and fall or autumn. Hence seasons are caused on the Earth due to its tilted axis and its revolution round the Sun.
Rotation and day and night
The Earth spins or rotates around its own axis and it takes 24 hours to complete one rotation. Due to this spinning of Earth, it seems as if the Sun rises in the East in the East and sets in the West in the evening. While the Earth rotates, the half part of the planet that faces the Sun experiences daytime while the other half that faces away from the Sun or in darkness experiences night.
I.m kishan, and write about our earth.
Earth, our home planet, is the only planet in our solar system known to harbor life. All of the things we need to survive are provided under a thin layer of atmosphere that separates us from the uninhabitable void of space. Earth is made up of complex, interactive systems that are often unpredictable. Air, water, land, and life—including humans—combine forces to create a constantly changing world that we are striving to understand.
Viewing Earth from the unique perspective of space provides the opportunity to see Earth as a whole. Scientists around the world have discovered many things about our planet by working together and sharing their findings.
Some facts are well known. For instance, Earth is the third planet from the sun and the fifth largest in the solar system. Earth's diameter is just a few hundred kilometers larger than that of Venus. The four seasons are a result of Earth's axis of rotation being tilted more than 23 degrees.
Oceans at least 2.5 miles (4 kilometers) deep cover nearly 70 percent of Earth's surface. Fresh water exists in the liquid phase only within a narrow temperature span (32 to 212 degrees Fahrenheit/ 0 to 100 degrees Celsius). This temperature span is especially narrow when contrasted with the full range of temperatures found within the solar system. The presence and distribution ofwater vaporin the atmosphere is responsible for much of Earth's weather.
Near the surface, an ocean of air that consists of 78 percent nitrogen, 21 percent oxygen, and 1 percent other ingredients envelops us. Thisatmosphereaffects Earth's long-term climate and short-term local weather; shields us from nearly all harmful radiation coming from the sun; and protects us from meteors as well. Satellites have revealed that the upper atmosphere actually swells by day and contracts by night due to solar activity.
Our planet's rapid spin and molten nickel-iron core give rise to amagnetic field, which the solar wind distorts into a teardrop shape. The solar wind is a stream of charged particles continuously ejected from the sun. The magnetic field does not fade off into space, but has definite boundaries. When charged particles from the solar wind become trapped in Earth's magnetic field, they collide with air molecules above our planet's magnetic poles. These air molecules then begin to glow and are known as theaurorae, or the Northern and Southern Lights.