Studying Nature , Exploring The Universe

 People first gazed up at the stars and thought the sky was our  universe. Our view was limited by what our eyes could see. Then telescopes deepened our views. The stars which can be seen constitute only a tiny part of the whole universe. It is impossible to form a mental picture of the universe because it is so vast and its extent is unknown.

 The universe contains all the Galaxies(huge collection of stars), our Galaxy-the Milky Way), stars and planets. Stars derive their energy from nuclear reactions going on in their interiors, generating heat and light. The apparent brightness of a star depends upon its temperature, its size and its distance from us.

In 1609 Galileo using a homemade telescope could discover four moons orbiting Jupiter and resolved Milk Way galaxy into countless stars. Milk Way galaxy is seen as a faint arc of light stretching across the middle of the sky on a clear night.

 Astronomers use tools such as telescopes, cameras, spectrographs and computers to analyse the light that astronomical objects emit. Telescopes today view the entire spectrum of electromagnetic radiation sweeping the universe. Each new advance in wavelength coverage has altered our view  of the universe.

 In spectroscopic study total light from a star is separated into its various wavelengths, and the intensity of each is measured. The temperature and chemical composition of stars can be obtained by this method, as well as information about stellar motion and magnetic fields.

 Astronomers use existing data i.e. records of astronomical events.In modern astronomy astronomers use computers to simulate astronomical events. (using mathematical models  and sky observations to match the motion of celestial bodies and the events )

 Ex: from records: 1. Planetary alignments remain a beautiful and interesting,  but safe curiosity on the sky.  Planetary alignments do not cause disasters can be found by simply looking at history. Neither the 1982 alignment nor the 2000 alignment caused any problems on our planet. 2. Earthquakes are specific to certain areas(around the edge of the plates that make up the Earth’s hard outer layers and where rocks move along faults). The record of earthquakes show certain periodicity at different places. And supermoons have a association with earthquakes.

 Radio telescopes are used to receive the radio signals  from outer space which are extremely weak. Radio telescopes are mounted so that they can automatically track a given object as its position changes because of the rotation of the earth. Performing astronomy from the earth’s surface is limited by the filtering and distortion of electro magnetic radiation due to earth’s atmoshphere.  Satellites are used for such studies.

 A constellation is a group of stars visibly arranged in a particular configuration or shape. All the stars of the sky are grouped into 88 constellations. But not all constellations are visible from any one place on earth. The ancients divided the heaven into twelve sectors which they called the signs of the zodiac. The signs were named after twelve of the constellations around the horizon. The zodiac was used for measuring time because the stars rotate in an anticlockwise direction through one sign in two hours.

 The  earth is surrounded by a blanket of air, which we call the atmosphere. It reaches over 560 kilometers from the surface of the earth. So we are only able to see what occurs fairly close to the ground.

Wind is the horizontal movement of air caused by differences in atmospheric pressure, which are primarily attributable to differences in temperature due to differences in thermal properties of land and ocean surfaces.   Eearly attempts at studying the nature of atmosphere used clues from the weather, the beautiful multi-colored sunsets and sunrises, and twinkling of stars.

  Storm is any disturbed state of atmosphere affecting earth’s surface. Different types of storms: cyclone or hurricane (accompanied by high winds and heavy rains), tornado( small but intense storm with very high winds).

 Tides are the periodic rise and fall of the gravitational attraction of the moon and the sun acting on the spinning earth. As the wind blows pressure and friction forces associated with the wind perturb the equilibrium of the ocean surface. Supermoons have a historical association with strong storms very high tides , extreme tides and also earthquakes.

 Climate has profound effects on vegetation and animal life, including humans. It plays statistically significant roles in many physiological processes, like growth, health and disease.

  The early human settlements are found in areas which provided favorable  environment for making town living relatively easy, climate and soil favorable to plant and animal life.-an adequate water supply , ready materials for providing shelter, and easy access to other people by favorable  government policies. After the industrial revolution and the coming of better roads and railways the cities grew at a fast speed. We find few old cities are over populated. Life in such cities become relatively difficult. Use of advanced technology and appropriate government policies can get us out of such situations.