Anupama Nair
As per modern science, our Sun is also a star, and there are nine planets — Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Pluto in the solar system. Mercury is the planet closest to the Sun, while Pluto is the farthest. As far as we know, Earth is the only planet inhabited by living beings, however, we may discover, worlds unknown to us. The Sun is only a part of the galaxy called Milky Way or Akash Ganga as our rishis called it and is one of at least 100 billion stars in a ‘spiral galaxy’ about 100,000 light-years away. What is a galaxy? A galaxy is a constellation or group of stars.
What is a light-year? As per modern astronomers, “the light-year is a unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers or 5.88 trillion miles”. The International Astronomical Union, in simple terms defined a light-year as “the distance that light traveled in vacuum in a year”.
The Milky Way is only one of the billions of galaxies in the universe. All the stars in our galaxy, Milky Way revolve around a ‘super massive black hole’ at the galaxy's center, which is estimated to be four million times as massive as the Sun. Do we need to worry about this explosive black hole? Fortunately, for us, it is a safe distance from Earth, and at around 28,000 light-years away. Within our universe, itself there are at least 100 billion stars, and on average, each star has at least one planet orbiting it. What is mind boggling is that there are potentially trillions of planetary systems like our solar system within the galaxy, waiting to be discovered!
What is the universe? “The universe is a vast expanse of space which contains everything that is in existence. The universe contains all of the galaxies, stars, and planets”. The exact size of the universe is still unknown. Scientists believe that the universe is still expanding outward every day. What is surprising is that ninety-five percent of the universe is ‘dark energy and dark matter’. Our earth and other stars only constitute five percent of the universe. The matter and energy are equivalent and “scientists have been able to calculate that whatever dark energy is, it comprises about sixty-eight percent of everything in the universe. The dark matter then, accounts for twenty-seven percent, leaving only five percent for protons, neutrons, electrons and photons – in other words, everything we see and understand”. I am asking you to imagine how big the universe is! “The 100 billion galaxies in the observable universe, each one brimming with stars form a bubbly structure, in which vast sheets and filaments of galaxies surround gargantuan voids”, quoted a scientist.
(to be continued….)
