OUR LOCATION IN THIS UNIVERSE.

OUR LOCATION IN THIS UNIVERSE

     We know very well that we are on the planet Earth. But we have to know where exactly our planet Earth is located in the universe. To start with we must know at least something about our planet Earth.

     The Earth is the third planet from the Sun after Mercury and Venus, orbiting the Sun at an average distance of about 150,000,000 kilometres from the Sun. Its diameter at the equator is 12,756 kilometres. It is the densest of all the planets in the solar system, with a density of 5.50. Earth’s axis is tilted at an angle of 23 degrees and 27 minutes to the plane of its orbit. This inclination of its axis causes seasons on Earth. About 71% of its surface is covered by water and 29% by land. Earth’s atmosphere contains about 78% Nitrogen, and 21% Oxygen. The Earth has only one moon, rotating around Earth at an average distance of 384000 kilometres, covering about 27 days (which is considered to be the same as the menstrual periods interval of women; most of the astrologers believe that the menstrual periods of women are related to the motion of moon with respect to their birth moon). The Moon always keeps the same side towards the Earth. Earth is the only planet with life in the solar system. The other planets in the solar system are Mars, Jupiter, Saturn, Uranus, and Neptune.(Pluto is now not considered as a planet). Jupiter is the biggest planet in the solar system. Its mass is 318 times that of Earth.

     The Sun around which all the planets of solar system revolve is a star. A star may be defined as a self luminous body of gas. The Sun contains about 99% of the total solar system mass. Its diameter is 1,392,000 kilometres. It can contain more than one million Earths in it. Sun contains large amount of hydrogen. Four atoms of hydrogen combine to form one atom of helium. In this process lot of energy is liberated and this makes the Sun shine. Also many varieties of particles are liberated besides light. One such small particle is neutrino. Neutrinos are small neutral particles produced by the atomic reactions in the Sun. 60 billion neutrinos pass through our thumbnail every single second without harming us. This indicates how small the size of a neutrino particle is. It seems the neutrinos are passing through human cell without crossing nucleus of the cell. Some are of the opinion that if these neutrinos pass through nucleus of human cell there may be great reaction. Can it be instantaneous human combustion? It is not known yet to science.

     Our star, the Sun is located in the Galaxy known as Milky Way which contains about 100 billion stars approximately. The diameter of our galaxy is 100,000 light years (A light year is the distance travelled by light in one year at the rate of  300,000  k.m. per second). Our galaxy is a barred spiral galaxy. Sun’s galactic rotation period is about 225 million years (Also known as cosmic year). The galactic center is about 27000 light years from us. The solar system is almost to the edge of our galaxy. The orbital speed of solar system about the center of galaxy is about 220 kilometres per second.\

     There are unlimited numbers of galaxies in the universe. The nearest star to our solar system is Proxima Centauri of the constellation Centaurus at a distance of 4.39 light years from the Sun. The nearest galaxy to us (other than our galaxy, Milky way) is The Large Megellanic cloud, about 160000 light years from us. This galaxy revolves around our galaxy, Milky Way. Another galaxy known as The Small Megellanic cloud is at a distance of 200000 light years from us. One of the most important galaxy, known as The Andromeda Galaxy which is also a spiral galaxy and similar to our galaxy is at a distance of about 2,500,000 light years from us. This Galaxy is moving towards our galaxy at the rate of 300 kilometres per second and the two galaxies are likely to collide in a few billion years time and will result in a single massive galaxy and in an enormous burst of star formation.

     Our galaxy, The Milky Way galaxy is located in a group of galaxies known as Local Group. This local group contains The Milky Way galaxy, The Andromeda galaxy, The Triangulam galaxy and other smaller galaxies. This local group may be considered as a part of Virgo Super Cluster. This cluster contains most of the elliptical type of galaxies. It is even difficult to distinguish individual galaxies among thousands of elliptical. Somewhat less than the half of the mass Virgo Cluster lies in the form of galaxies. The rest is the hot gas that fills the space between them. The gas is not static. Lot of energy from the center of cluster is flowing out to edge of cluster through gas.

     This Virgo Super Cluster may be considered as part of large scale structure of the cosmos and everything is a part of observable universe. This observable universe is only a negligible part of total universe constituting only 5% of the total universe. The rest of the universe cannot be observed even through telescopes. (My post on ‘Matter, Dark Matter and Dark Energy may please be verified).

     If we assume the size of the humans as 10^0 (i.e. one ) metre, the size of Earth is 10^6 metres and the size of the Universe is 10^25 (10 to the power 25) metres. This indicates where we stand in the universe in terms of size. This is only the size of the observable universe what we can see through telescopes, by study of light rays. Beyond the observable universe, to what extent the universe exists nobody knows. Light rays have to still reach the earth from beyond the observable universe. Some say that the universe is having infinite size. Some believe in parallel universe. In both cases they believe that people like us (exact twins) with similar circumstances and similar surroundings exist somewhere in the infinite universe or in the parallel universe.  Simply we do not know exactly where we are in this vast universe because we do not know the boundaries of the universe. We have to wait and see for further development of science.