The Universe: Are you looking for Geography GK of the universe chapter. Here we have published the universe Gk with Big Bang Theory and Dopler effect.
Welcome all of you to the Universe, chapter of Geography GK. In this chapter, we will discuss the Universe, Doppler effect, Big Bang theory of the universe, Galaxies, Local Group, and Red Shift.
What is the Universe?
The Universe is commonly defined as the totality of everything that exists, including all physical matter and energy, the Planets, Stars, Galaxies and the contents of intergalactic space.
The study of the universe is known as Cosmology
The universe comprises of billions of galaxies. The galaxies are made up of millions of stars held together by the force of Gravity.
Andromeda is our Nearest Galaxy
One can observe in the night sky, various patterns formed by different groups of stars. These are called constellations.
Ursa Major or Big Bear or Saptarlshi Mandala is one such constellation.
Among the others, there is the ‘North Star‘, which indicates the north direction (North Pole). It is also called the ‘Pole Star‘. It always remains in the same position in the sky.
Some essential bodies that do not have their own heat and light. They are lighted by the light of the stars. Such bodies are called Planets.
The word ‘Planet’ comes from the Greek word “Planetai” which means wonders.
What is Galaxy?
Galaxy is giant assemblies of Stars, Planets, Gases, and dust. These stars occur in huge bunches or clusters. They are so big that they have sometimes been called Islands Universe. Milky Way and Andromeda are two examples.
Our Own galaxy is called the Milky Way and it contains about 300 billion Stars and one of these is our Sun. Planets and other objects go round the Sun and make up the solar system with the Sun at the center.
In India Milky Way (Our Own Galaxy) is popularly Known as “Akash Ganga“
There are three types of Galaxies, as follows:
- Spiral Galaxies
- Elliptical Galaxies
- Irregular Galaxies
Our Milky Way galaxy is a spiral Galaxy.
In AD 140, Ptolemy proposed the theory that the Earth was the center of the Universe and the other heavenly bodies revolved around it.
In 1543, Copernicus said that the Sun is the center of the universe and not earth.
Kepler supported Copernicus but suggested that the Sun is the center of the Solar system, not the universe.
In 1924, Edwin Hubble first demonstrated the existence of galaxies beyond Milky Way.
Also Read: The Solar System and the Sun
Evolution of Universe
The three main theories put forwarded to explain the origin and evolution of the universe are:
- Big Bang Theory
- Steady State Theory
- The pulsating theory
Big Bang Theory
Big Bang Theory was proposed by Georges Le Maitre.
According to the Big Bang theory, about 10 to 20 billion years ago, cosmic matter (universe) was confined in a superdense ball in a state of extremely high temperature and pressure.
Steady State Theory
Hermann Bondi,Thomas Gold, and Fred Hoyle devloped Steady state Theory.
Steady state theory states that although the universe is expanding, it nevertheless does not change its appearance over time, it has no beginning and no end.
The Pulsating Theory
According to pulsating theory, the universe is supposed to be expanding and contracting alternatively i.e, pulsating. At present, the universe is expanding.
Doppler Effect and Red Shift
The shifting of light coming from the galaxies to the red end of the spectrum is known as the Red Shift. The red color band has the lowest frequency and the longest wavelength in the visible spectrum.
This proportionate increase shows that matter in the Universe is in a state of rapid expansion and this idea of rapid expansion is the basis of all the Modern theories about the origin of the Universe.
A cluster of 54 known galaxies is known as a local group. Milky Way and Andromeda are the two largest known galaxies.
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