Why did Copernicus revolutionize concepts about the Universe?

Copernicus is said to be the founder of modern astronomy. His investigations were carried on quietly and alone, without help or consultation.

He made his celestial observations from a turret situated on the protective wall around a cathedral. His observations were with just his eyes, as a hundred more years were to pass before the invention of the telescope.

In 1543, Copernicus published a book about a new idea he had. Most people in his day thought that the Earth was at the centre of the Universe. They thought that the stars were little holes in a glass ball that surrounded the Earth. But, Copernicus disagreed. According to him, the Universe is not centred around the Earth, but that the Earth is actually a planet circling the Sun. Not many people liked his book or his ideas, for they went against the philosophical & religious beliefs that had been held during the medieval times. Copernicus died in 1543, and was never  to know what a stir his work had caused. Of course, we know today that Copernicus was right!

Why did ancient astronomers observe the sky?

Beginning around 600 BC, ancient philosophers and scientists developed a number of important astronomical ideas by simply observing the sky, since they didn't have any modern tools or instruments to tell the time, location of a place or the nature of the Universe.

The ancient Greeks were able to figure out the shape and size of the Earth by calculating the height of the Sun or the stars. About 230 BC, Eratosthenes estimated the size of the Earth by using the Sun as a reference point. The sundial was another simple tool that depended on the Sun to let people know what time it was.

Sailors at sea used the stars above to guide them. In fact, Many early tribes of Polynesia and New Zealand have sailed great distances using the stars for navigation. The sun's position in the sky also allowed sailors to determine the latitude at which they were sailing. Another instrument called the 'qiblah' used the sun to find the direction of Mecca, so that Muslims could face in that direction for their daily prayers. So, you see ancient astronomers had many good reasons, to watch the sky, the Sun, stars and the Moon, day and night.

Why did astronomy spread and grow?

The earliest atronomers were priests and holy men, studying the movement of celestial bodies to chart celebrations and planting cycle. Their knowledge and theories of the Universe spread through two routes - trade and war. As great empires expanded, their gods, cultures, and learning influenced other cultures as well.

The ancient Babylonians were amongst the first to start developing theories about the design of the Universe. The Greeks and Romans later adopted the Babylonian system, replacing the names with the names of their own Gods. The earliest astronomical records are in the form of clay tablets that have been discovered in what was once Mesopotamia.

Early observers of the heavens realized that the repeated motions of the Sun, Moon and stars could be fashioned into a clock to tell the time of the day, and a calendar to mark the progression of the seasons. Many of the ancient monuments, in fact, show some of the features of an astronomical observatory.

Did you know that the earliest observatory to have survived is in Korea? It is a simple beehive structure with a hole in the roof.

Why is the astronomy called the first science?

Astronomy, or the study of the stars, began as a science only about 2,500 years ago, though people have been gazing at the heavens for millions of years. In the beginning, Man had only a few crude hand tools. Using these tools, and some mathematical calculations, he tried to find some explanation for the changing seasons, the floods, the droughts, sunrise, sunset, and all the other mysteries of nature.

Some of these explanations were very primitive and strange. But they are important, because they made people think and ask, and it is this spirit of curiosity that replaced imaginations with scientific observation and reasoning. This is why astronomy is called the first science.

What are cosmic rays?

Cosmic rays are tiny particles that slam into the Earth's atmosphere at various levels of energy. Billions of cosmic rays are slamming into the Earth every second, most of them with a quite low energy. Although they are called 'cosmic rays', it should be noted that cosmic rays are point-like atomic particles. They are called cosmic rays because they are found everywhere in the Universe.

Astronomers believe that cosmic rays reach their high speeds because of the action of magnetic forces in space. There are two types of cosmic rays - primary and secondary. Their study provides scientists with information about the structure, operation, and history of the galaxy and of the Universe.

What is the relationshipe between matter and energy?

Matter is the material which makes up all things on Earth. Energy is simply the capacity for doing work. Matter comes in three states - solids, liquids and gases, and energy comes in many forms too. The most common forms of energy are kinetic energy and potential energy. Kinetic Energy is energy due to motion, and potential energy is the energy that is stored in an object that can be converted into kinetic energy.

Scientists now think that matter is formed as a result of the 'freezing' of energy. They believe that the particles that make up matter began to form out of some of the energy, when the Universe became cooler, after the 'birth' of the Universe.

What is light?

Throughout human history, light has been something Man has taken for granted. We know that it comes out of the Sun or a lamp, let us see things, and makes us warm. But what is it?

Light is a form of energy. It consists of photons that move in waves. The size of a wave is measured as its wavelength. Light can move through a vacuum, and its speed can be measured.

The white light that we see it not white at all. It is actually a mixture of all colours. The band of this mixture is known as a spectrum. The different colours in the spectrum have different wavelengths. So, we know many things about light, but it is still difficult to define it exactly!

What is Parsec?

Parsec is another unit of distance. It was introduced when people started measuring the distance to nearby stars using the parallex method. It corresponds to the distance at which the mean radius of the Earth's orbit stretched an angle of one second of arc. One parsec is equal to about 3.258 light years. It is used to measure distances in astronomy since it is a convenient size to measure such large distances.

Some universal facts

• Far Far Far Away!
  The galaxy named Abell 1835 IR 1916 is the most distant object in the Universe, according to the European Southern Observatory, in Chile. It is about 13,230 million light years away from us.
• The Big Eye!
  The NASA Hubble Space Telescope, which weighs 11 tonnes, is the largest space telescope. It is 13.1 metres long with a reflector of 240 centimetres in diameter. It was placed in the orbit, on April 24, 1990 by the space shuttle Discovery. Did you know that it cost around 2.1 billion dollars to NASA to make this telescope?
• The Largest!
  The twin Keck Telescopes, situated on the summit of a dormant volcano in Hawaii are the largest optical and infrared telescopes all over the world.
  

What is a radio telescope?

Almost all objects in the Universe emit radiation at radio wavelengths. A radio telescope is an instrument that is able to receive and record radio waves from space. The record of the signal is then analysed by astronomers, using sophisticated software. In order to collect incoming radio waves, the instrument is equipped with one or more antennas. Karl Jansky accidently built the first radio telescope while working at Bell Telephone Laboratories.

Why is it now possible to measure distances from the stars?

Scientists cannot stretch a measuring tape from the Earth to a nearby star, so how do they know how far away they are? It's always been known that the stars are very remote, but it was not until 1838, that the first star distance was measured, using the method of parallax, by F W Bessel. A star, viewed from different points in the Earth's orbit will shift against its background of more distant stars. The deviation in the angle can be used to calculate the distance.

Today, scientists use special cameras to calculate distances. Special types of telescopes are used to photograph large areas of the sky. Scientists also use instruments like a spectroscope, radio telescope, etc. to determine how far is a star from our Earth.

Light years are the unit of distances in space. This sounds like a unit of time, but a light year is actually the distance that light travels in one year. Light travels 299,792 kilometres per second. So, a light year is about 9,460,700,000,000 kms long.

It has been calculated that the nearest galaxy is the Andromeda, which is at a distance of 2.2 million light years, from Earth.

Did you know that the Sun is positioned only 8 light minutes away from Earth?

The Worlds Beyond

Since time immemorial, people have been fascinated by what they saw in the sky. They mapped the sky, scaled the time, and prepared calendars based on the study of celestial bodies to develop the oldest branch of science - astronomy. Later, Greek, Babylonian, Egyptian, Indian, Chinese, and many other civilizations all over the world contributed to it. Today, we know a lot more about our Universe, thanks to the great leaps in knowledge and technological advances. Now, 2009 is being celebrated as the years of astronomy, as a commemoration of the 400th anniversary of the first recorded astronomical observations with a telescope by Galileo, and the publication of Kepler's book 'Astronomia Nova'. The aim of this celebration is to create interest among young people, in astronomy and science under the central theme, 'The Universe, Yours to Discover'. In this blog, you can read about the past, present, and future of the Universe, and the unimaginable phenomena taking place in it. Welcome to the stunning worlds beyond.