Prof Dr Jaipal Singh
With the invent of spectroscopy in the late 19th century, astronomers met their first tool for analyzing the light of stars. They could now learn how stars 'worked'.
This was really the beginning of astrophysics. Astrophysics is basically the attempt to understand the physical processes involved in the formation of Universe.
It deals with numerous questions such as:
n how do stars and galaxies form and evolve?
n when did the first star form?
n how are the components of a galaxy, stars, dust, gas and 'dark matter' related to each other?
n what are the different components of the Universe, how much of each is there, and where are they found?
We get most of our information about the Universe from electromagnetic radiation: the visible light, radio waves, X-rays, infrared radiation, ultraviolet rays and gamma rays emitted by stars, dust and gas, in our Galaxy or other galaxies.
Astronomers use the Telescope(s) to collect the radio waves emitted by cosmic objects such as stars, gas clouds and whole galaxies. They then analyze the data to answer the questions of astrophysics.
Exoplanets
It appeared a near certainty that other planets must orbit other stars. And yet, it could not be proven, until the early 1990's. Then, radio and optical astronomers detected small changes in stellar emission which revealed the presence of first a few, and now many, planetary systems around other stars. We call these planets "exoplanets" to distinguish them from our own solar system neighbours.
The Big Bang
The night sky view presents a picture of calm and unchanging Universe but the revolutionary discovery of 1929 by Edwin Hubble that the Universe is in fact expanding at enormous speed changed the whole view of universe. Hubble noted that galaxies outside our own Milky Way were all moving away from us, each at a speed proportional to its distance from us. He quickly realized what this meant that there must have been an instant in time (now known to be about 14 billion years ago) when the entire Universe was contained in a single point in space. The Universe must have been born in this single violent event which came to be known as the "Big Bang." Prior to this explosion there was a vast unlimited space but matter was confined to a point.
Dark Energy, Dark Matter
What we see or can see all around us even with the highly powerful tools and latest inventions till date we know less than 5% of the whole universe and rest part is dark with respect to our knowledge which includes Dark Energy (70%) and Dark Matter(25%)
n Stars
How do stars form and evolve? Stars are the most widely recognized astronomical objects, and represent the most fundamental building blocks of galaxies. The age, distribution, and composition of the stars in a galaxy trace the history, dynamics, and evolution of that galaxy. Moreover, stars are responsible for the manufacture and distribution of heavy elements such as carbon, nitrogen, and oxygen, and their characteristics are intimately tied to the characteristics of the planetary systems that may coalesce about them. Consequently, the study of the birth, life, and death of stars is central to the field of astronomy.
n Galaxies
Our galaxy, the Milky Way, is typical: it has hundreds of billions of stars, enough gas and dust to make billions more stars, and about six times as much dark matter as all the stars and gas put together. And it's all held together by gravity. Like more than two-thirds of the known galaxies, the Milky Way has a spiral shape. At the center of the spiral, a lot of energy and, occasionally, vivid flares. are being generated. Based on the immense gravity that would be required explain the movement of stars and the energy expelled, the astronomers conclude that at the center of the Milky Way is a supermassive black hole.
n Black Holes
Don't let the name fool you: a black hole is anything but empty space. Rather, it is a great amount of matter packed into a very small area - think of a star ten times more massive than the Sun squeezed into a sphere approximately the diameter of New York City. The result is a gravitational field so strong that nothing, not even light, can escape. In recent years, NASA instruments have painted a new picture of these strange objects that are, to many, the most fascinating objects in space. What happens at the edge of a Black Hole ???
The author is Professor at
G.D.C. - R.S.Pura |
