‘TWINKLE, TWINKLE LITTLE STAR
HOW I WONDER WHAT YOU ARE’
THE HISTORY OF THE STARS IN THE SKY
TWINKLE, TWINKLE LITTLE STAR,
HOW I WONDER WHAT YOU ARE.
UP ABOVE THE WORLD SO HIGH,
LIKE A DIAMOND IN THE SKY.
TWINKLE, TWINKLE LITTLE STAR,
HOW I WONDER WHAT YOU ARE.
Aim: Conduct a research study looking at the detailed history of the stars.
As we stare up into the sky, we see tranquil, bright lights twinkling gently at us. However, stars are actually exciting, dynamic objects in the Universe. Stars are great balls of burning gas – larger and hotter than one can ever imagine. During previous years of primary and secondary school, I have learnt a little about stars. For example, I know that the Sun is the Earth’s parent star. In the core of the Sun, nuclear reactions that involve hydrogen and helium take place. This creates huge amounts of energy, which is radiated as light and heat energy. The Sun sources almost all the light and heat energy on Earth – without it, the Earth would be a cold and desert place. I also know that stars give out light at all times. However, the intensity of the Sun’s light blocks out other stars during the day. This is not necessarily because the Sun is the most luminous star, but because it is closest to us. For example, a star called ‘Sirius’ is 26 times brighter than the Sun, but as it is so far away, it seems less bright. The stars make patterns known as constellations. These constellations all have names. For example, there is ‘Orion’s Belt’, ‘The Plough’, ‘Leo the Lion’, and many others. Interestingly enough, stars in the Northern Hemisphere seem to rotate anti-clockwise around ‘Polaris’ – more commonly known as the Pole or North Star. In the Southern Hemisphere, stars seem to rotate clockwise. The truth is that stars do not move at all. It is the Earth that rotates on its axis, which induces one to believe that the stars are moving. Stars are formed when the gases and dust in galaxies are pulled together by gravitational forces.
I hold a great interest in this topic of Physics – however, my knowledge of stars alone is very generalised. Hence, my aim is to increase my knowledge and learn details of all the major aspects related to a star. My preliminary research has included visiting museums such as the Science museum and Natural History museum in London, where exhibitions based on the universe include details about the stars and history of how they came around. I have also visited the Royal Observatory in Greenwich, which features great information on astronomy. As well as this, I have researched textbooks, CD-ROMs, carried out a number of Internet searches and watched various different astronomy related programmes on television and videos. Further to this, I will continue researching throughout the duration of my work. I have a great many questions – and hope that by the end of this research piece, I will have found all the answers.
This is a preview of the whole essay
‘Twinkle twinkle little star, how I wonder…’ what you are (the astrophysics and content of a star), how far you are (distance between Earth and stars), how you came about (the birth of a star), when you were (the life and death of a star), and where you are (the galaxies).
Astrophysics is a sector part of astronomy. It combines chemistry and physics to find answers about extraterrestrial objects including stars. The content of stars is always determined by astrophysics. Content can vary from star to star. In some gases of stars, the air could be very thin and in others, extremely dense. Stars consist of hydrogen, oxygen and nitrogen. Some stars may even contain iron, calcium and many other elements. Powerful chemical reactions take place each second with all the different elements involved. Depending upon the coolness of the star, the matter can be almost liquid-like. In very old and cold stars the matter may be packed so tightly that it is almost solid. Many other elements become involved as the star goes through different stages of its life.
When we look up into the sky in the night, stars seem so far away – and indeed they are. The huge distance between the stars and us is measured in light years. One light year is the distance light travels in one year, which is an enormous 5,880,000,000,000 miles! The closest star is called ‘Alpha Centauri’, which is around 4.3 light years (2.52 x 10¹³ miles) from Earth.
The theory about stars, as I have mentioned before, is that they do not move at all – and it is because the Earth is rotating on its axis that they seem to be. However, some investigations have shown that stars are actually moving! Apparently, the sun and solar system are moving closer towards the constellation – ‘Hercules’ – at about 12 miles per second.
The birth of a star is a most magnificent thing. It is quite a long and complicated process. The birth begins when a combination of dust, hydrogen and sometimes, helium, gather. These clouds are usually very dense. The core becomes hotter and hotter until atoms lose electrons and the matter collapses. This is due to great gravitational forces. The gravitational contraction causes further increase in density and temperature. Gases in the core of the cloud begin to apply an outward pressure, which ceases the collapse. Finally, after unwanted dust and particles are vaporised and blown away, a star cluster is left. Temperature in the center continues to increase, destroying the many dense gases that helped form the cluster. A process known as ‘nuclear fusion’ then begins. The exact definition from the ‘Oxford Dictionary’ of nuclear fusion is: ‘nuclear reaction in which nuclei of low atomic number fuse with release of energy’. Nuclear fusion thus takes place over a period of time until the star enters the next stage of its life – the main sequence.
Like all living things, after birth, stars go on to live life and then eventually die. The different stages of a star are as follows:
THE LIFE OF A STAR
Actually, the life of a star varies according to its mass. This means that the life of a small star and a much larger one would be quite different.
THE LIFE OF A SMALL STAR
After the main sequence, a small star becomes a red giant. As it contracts and becomes increasingly hot, the star’s outer layers are lost and it is then a white dwarf. Millions of years later, all that is left is an invisible black dwarf.
THE LIFE OF A MASSIVE STAR
After the main sequence, a massive star becomes a red supergiant. The supergiant has the same principles of a red giant. However, the supergiant is obviously much larger. After the red supergiant, the star begins generating energy again and is known as a blue supergiant. In the supernova explosion, the star loses its outer layers, leaving a neutron star or black hole.
As well as being classed by the stage of life they are in, stars can also be classed by heat intensity. The temperature of a star is determined by its luminosity. The temperatures are measured on the ‘Kelvin Scale’. These details are arranged in a chart known as the ‘Draper Catalogue’. The types of stars are arranged into different letter groups as shown below:
* R and N stars are cool enough to form molecules, which consist mainly of carbon. They are classed as carbon type stars.
** S stars contain zirconium oxide.
All the millions of stars in the universe are grouped into ‘galaxies’. There are many galaxies in the universe, some smaller than others. Our galaxy, the ‘Milky Way’, contains around one hundred billion stars. It is around 100,000 light years in diameter. The shape of the Milky Way is spiral – it is a flat disk and quite irregular.
The most important star to Earth is, of course, the Sun. Although the Sun is rather ordinary compared to the other stars in the Milky Way, it is special to us as it sources almost all the natural energy we, on Earth need. Below is a list of some important facts about the sun:
From my results, I most certainly can say that stars are indeed very interesting objects. It is no wonder that one of the most popular nursery rhymes is based on stars. I have found out that the content of a single star is enough to create such amazing and powerful chemical reactions – so great, that it is probably impossible to ever create such a reaction on Earth. The absolutely huge distances between the Earth and the stars in the sky are so great that it would take years to reach even the nearest star - Alpha Centauri. The birth of stars is so complicated that they take millions of years to be complete. The life and death of a star is also long, complex and vigorous. As well as this, I have learnt about the home to all these millions of stars and our galaxy. I have learnt some incredible facts about the Sun, such as the high temperatures that are reached on the surface and in the core.
The topic of stars is just one tiny part of astronomy. There are so many other great things in the universe – planets, comets, moons, and so many other things. The population of the universe is forever increasing. Recently, a tenth planet has been discovered and named Sedna, after the Inuit goddess of the sea. It is two billion miles further from the sun than the ninth planet, Pluto and around 5.5 billion miles away from Earth. It is said that it would take a space shuttle around 45 Earth years to reach it. The nursery rhyme, ‘twinkle, twinkle, little star’, is a lovely tune but has no answer – in this piece of research, I have been able to find the best answer I could give. The Earth, other planets and stars including the sun will eventually end, leaving nothing but darkness.
1. Compton’s Interactive Encyclopaedia 2000
2. BBCi Space (bbc.co.uk/science/space)
3. Heinemann Physics for AQA Coordinated Award Student Book (Published 2001)
4. BBC – GCSE Bitesize – Physics – Earth and Beyond
5. Oxford Colour Dictionary (Published 1998)