What is a supernova?

-Rahul Ramachandaran, Chembur, Mumbai

Have you seen an earthen lamp burning? Just before it extinguishes, it suddenly burns brighter. Supernova signifies the death of stars! It is the name given to a star that starts burning more brightly than usual and then the brightness of which suddenly decreases. All stars derive their energy by a reaction similar to that of a hydrogen bomb. Two atoms of hydrogen fuse to form an atom of helium and in this nuclear reaction immense energy is derived. Over a period of time, the stars exhaust their fuel -- that is hydrogen. This has a certain effect on the stars.

When the fuel is exhausted, there is explosive activity. The star casts off a considerable portion of its mass, after which it collapses into a neutron star. Immense energy is released during such collapse. Astronomers say that this could be one cause of supernovae (plural of supernova). They also say, at least some supernovae may not originate as stars, but could be due to gravitational collapse of enormous clouds of gas and dust.

Supernova are millions of times brighter than the sun. At times, a supernova may be brighter than all the rest of the stars in its galaxy put together! This high luminosity is maintained for a week or two. Since 1885, more than 200 supernovae have been observed in external galaxies.

How and when did the game of football begin?

--Jignesh S Patel, Surat

There are records that the football was played in China as early as 300 BC. A similar game, called Harpestam, used to be played in ancient Greece. The Romans learnt the game from the Greeks and perhaps were responsible for introducing the game in Britain, although according to one historian, the Irish people played a similar game around 100 BC.

In Britain, the game became so popular that King Edward II issued a decree in 1365, forbidding people from playing football because they were paying less attention to practising military skills.

Is it true that the phases of the moon affect the temperament of people living on earth? If yes, then how and why?

--Rupa G Rao, Mahim

For centuries man has believed that the phases of moon have something to do with the behaviour and temperament of people on earth. In fact, in Britain and much of Europe, 200 years ago, crimes committed by people, who were termed lunatics on full moon nights were judged more leniently by the courts. It was considered normal for lunatics to get excited on full moon days. As a preventive measure, patients in lunatic asylums were often beaten the day before a full moon in Britain.

The American Institute of Medical Climatology had reported about 18 years ago that crimes like arson, rash driving and heavy drinking show a marked increase on full moon days.

What is meant by the word `clone'?

--Amiruddha Agarwal, Andheri (W), Mumbai

There was a sensation in the world of science when the news was splashed that Dolly, a seven-month-old sheep had been produced by cloning.What is cloning? Normally an egg (ovum) from the mother has to be fertilised by a sperm cell from the father to give birth to one or more similar organisms of the same species, in the case of mammals. Dolly was produced without such fertilisation. She came only from the mother sheep. She was produced by taking an egg from the mother, then the nucleus of the egg was removed. A single cell was taken from the mother's udder. The two were made to fuse using an electric impulse. After the fusion took place the growth was very fast.The result after full growth was Dolly, exactly looking like her mother, but produced without mating with a male sheep.

What is a palindrome?

--Divya G Nair, Mulund (W), Mumbai

A palindrome is a word which can be spelt backwards in the same sequence of letters as when you read it from left to right.

The word `malayalam' is a palindrome.

Copyright © 1997 Indian Express Newspapers (Bombay) Ltd.