Question

Elucidate the astronomical methods that have provided insights about the universe.

Answer 1

Now my own suspicion is that the universe is not only queerer than we can suppose but it is queerer than we can suppose. This remark of Haldane, a famous scientist, reflects, in a way what we feel about this subject. The universe is rather a difficult subject to study. We cannot bring it to the laboratory  to carry out experiments on it. We cannot compare it with any other universe this is the only universe we have. And finally we are a part of it. We can study it only from within. We cannot go out of it and look at it from the outside. So how do we study it. It is here that the scientific method comes to our aid. The easiest method of studying light from a cosmic object is to collect it through a telescope and record it on a photographic plate. Photographic films are exposed for a long period of time-sometimes night after night- to the light being collected by a telescope aimed at distant stars. Since the earth rotates on its axis, the stars appear to move in the sky. The telescope is rotated following the daily movement of stars at which it is aimed. Thus, its movement is synchronized with the movement of the stars being studied, stars too faint for the human eye slowly begin to register on the plate. This method of collecting and investigating light from the cosmos is called optical astronomy. As of today a huge optical telescope called the Hubble space telelscope after Edwin Hubble is in orbit around the earth. Several large telescopes are stationed in Hawaii, Australia Chile Russia UK etc. Many smaller telescopes scan the skies every night adding to our knowledge of the cosmos. The fact that stars emit radiowaves was discovered accidentally in 1932 by a young engineer Karl Jansky. He was trying to find the source of noise in a transatlantic telephone link. He make an experimental radio receiver set to study this problem. To his surpise he found that the disturbance was due to the rasio waves coming from  the milky way galaxy. This was the beginning of radio astronomy, i.e. the study of cosmic objects through radiowaves emitted by them. The radio telescope, a basic tool of radio astronomy, collects radiations from space in the radio wave region one of the largest radio telescope in the world was designed and set up by Indian astronomers at Ootacamund. The other radio telescope, a basic tool of radio astronomy are stationed in Gulamrg, Ahemdabad, Bangalore. With the coming of the spaceage, observatories equipped with telescopes and ceramics could be placed right in space, beyond the earth’s atmosphere. An observatory in space may be in the form of an orbiting satellite like the Unamanned Orbitting solar observatories, Orbitting Astronomical Observatory, Skylab, Einstein Observatory, IRAS(Infra Red Astronomy Satellite) and many others. Instruments are also put abroad high flying ballons, rockets and aircrasts to record observations. These observations can record radiation from a cosmic object in the regions of the spectrum such as the IR,UV,gamma rays and X-rays that do not penetrate the Earth’s atmosphere.AS space research came of age it became possible to send spacecrafts to other planets and even land men on the moon. These ventures also provided a rich stock of information about the solar system. For instance, astronauts of the Apollo mission to the moon in the 1970’s bought back lunar rocks and soil samples, photographs of the lunar surface and left several instruments there for further study. We have been able to send space probes, across the solar System to know about our planetary neighbours. Space probes have visited a number of planets and a host of their moons, and successfully landed on the surfaces of Mars and Venus.