Astronomy

The word astronomy is from the Greek astron meaning stars. Astronomy is the scientific study of the heavens and all that in therein. In it is not to be confused with astrology which lacks any kind of scientific basis and encompasses the belief that heavenly bodies affect human lives. 

Modern astronomy begin with Italian astronomer Galileo . In 1609 Galileo heard of the telescope made by the Dutchman Hans Lippershey. He improved upon it and constructed an instrument that could magnify up to thirty diameter . It was this instrument are refractor telescope that heralded the era of optical astronomy. Galileo made several startling discoveries. He found that the Moon's surface is ragged and that pleiades is a group of over 40 starts . He discovered four of jupiter's Moon and observe the sunspot . 

In 1668 Newton invented a new instrument the reflector telescope . In refractor telescope light is gathered by a large objective lens .In a reflector telescope enlarged curved mirror is used for this purpose .Both types of optical telescopes are still in use.  The invention of the optical telescope was an epoch-making event in the history of astronomy. 

1609-Galileo pioneers telescopic observation, Kepler publishes his first laws of planetory motion. 

1672-Newton demonstrates his reflecting telescope . 

1666- Newton formulates his law of gravitation . 

1675-Greenwich Observatory founded in London. 

 Radio Astronomy in the most unexpected manner . In 1931 Karl Jansky, a US radio engineer working with Bell laboratory notice a steady stream on radiation coming in from outer space however an amateur radio operator in the US growth Robert set out by himself to learn more about this extraterrestrial phenomenon . In 1937 he built the world's first radio telescope a-9.58 parabolic desk and set it up in his backyard at Wheaton, Illinois . In 1940 he produced a radio map of the sky , the first of its kind in the world . Thus a new branch of astronomy. 

 the radio telescope is in many ways and analogous to the optical telescope in consists of a large metal reflector fitted with an antenna the metal reflector collect and focus radio energy on to the antenna which can be tuned to any desired frequency of All The Invisible ray streaming in from outer space only radio waves reach us at ground level through the  so-called radio -window other areas are blocked by the atmosphere radio astronomers pick up radio waves from outer space with specially designed radio telescope the signals are amplified billions of times before fed into the computer which analyse them and discover the image as false colour radio pictures. 

Radar Astronomy born in 1940 when a  Hungarian physicist zoltan bay send out a beam of microwaves to the moon and recorded the Eco. 

 Satellite Astronomy when Explorer I was launched in 1958 by US with a special instrument two doughnut shaped regions of intense radiation around the Earth (called Van Allen Belt) were discovered. This was how satellite astronomy started. 

The invisible rays given out by stars and galaxies belong to the same family of rays. They are  electromagnetic waves and form what is called electromagnetic spectrum that crucial difference between them is that they have different wavelength the wave include x-rays , ultraviolet rays,visible light,infrared ray microwave and radio waves . Now satellite have made it possible to study astral phenomena from to level from the ground and from above the atmosphere this has led to the emergence of many specialised field in astronomy x-rays ultraviolet gamma rays and infra-red. 

The Hubble revolution -The tonne  Hubble telescope built at a cost of US $1.5billions , is the most powerful optical telescope ever developed and launched in 1990. 

The new millennium probe series are the successors to Hubble telescope.