Welcome to..

ClearlyExplained.Com

 

Stars
ClearlyExplained.Com
1 August 2005

updated: 16 October 2005

by Richard Conan-Davies BSc Dip Ed

A straightforward and fast information
introductory overview to stars from
ClearlyExplained.Com

 


A collage of star images including the pleides and the sun, our closest star. images: derived from NASA

 

The | What | Why | News | How | History | Future | of Stars

What are stars?

Basically stars are huge balls of gas (mostly hydrogen) that are held together by their own mass producing an enourmous gravitational field enough to produce a constant fusion reaction in the core.

Stars can vary dramatically in size from a few kilometres across to several million kilometres across.

 


The pleides star cluster, a classic example of high temperature stars.
image: NASA

What

Why

News

How

History

Future

 


Why are stars important?

solar flareStars are important because our own the sun is a star. Although we normally think of stars in the night sky . By looking at stars we can discover how our own star, the sun works. By knowing how are own star works might help us avoid or prepare for possible dangers (eg solar flares that can disrupt communications)

Studying stars helps us discover how big our universe might be , it is about discovering where we came from. For example stars where needed to produce most of the elements in our bodies.


Stars also harbour the molecules for making up life
image: NASA/JPL

 

Why should we care about studying stars?

knowing about stars and the methods used for studying them can help develop technologies here on earth. For example the development of telescopes was partly because we wanted to view stars more closely.

Looking for stars that appear similar to our own star may gives a clue to finding out about the possibility of life on other planets.

star burstSome types of stars can be quite dangerous and if we can predict when and where they are likely to be a problem we might be able to be better prepared for possible problems.

 

 

 

What

Why

News

How

History

Future

 


News about stars

Stars are reported in the news almost daily, astronomers often report on new star discoveries, particularly stars that are unusually large, small or

  • Try a search of Google news for stars for some of the latest headlines around the world, although you may notice stories about celebreties and sports.
  • Try a search for astronomers and stars to get an even more relevant results.

 

Some reliable resources about stars

 

It is sometimes useful to visit local astronomical observatories or universities that study stars for the latest research areas.

What

Why

News

How

History

Future

 


How are stars studied?

Stars can be studied or considered in various ways and within different perspectives.

Nature of Stars
ClearlyExplained.Com

This is really about the physics and chemistry of stars. Typically it includes:

  • What they are made of
  • their physical sizes,
  • distances and ages.
  • how they interact with each other.

Technology and stars
ClearlyExplained.Com

This is about the how technology is used and developed from the study of stars.

  • For example super computers are used to simulate star behaviours.
  • The types of telescopes for studying stars

Culture and stars
ClearlyExplained.Com

This is the social & humanistic context of stars.

  • For example the music and creative aspects inspired by stars.
  • It can also include ancient mythologies .

How do stars work?

How does a star become so bright? is it burning? A star is mostly converting hydrogen gas into helium through a process called fusion.

 

 

How are stars classified or categorised?

The main way astronomers tend to classify stars is by looking at how big or bright they are and their colours.


This image of the Southern Cross constellation shows just how many stars there are in a small section of the night sky. If you sort out this collection into temperature and luminosity of stars you will get a HR- diagram(below)

image: Research School of Astronomy and Astrophysics, ANU

If you look at a whole bunch of stars in the night sky you can plot out their colours and their colours(temperature) into something called a Hertzsprung-Russel Diagram (HR-Diagram).

The dot in middle shows roughly where our sun is located in comparison to other stars.

reference: HR-diagram - wikipedia

 

What

Why

News

How

History

Future

 


What is the history of stars?

The natural history of stars

The history if stars is really about the history of the universe itself. Stars were one of the first things to have come into existence after the big bang. These first stars have since 'burnt' out and the earliest stars that astronomers see today were probably made from those very first stars.

It is thought that the first stars formed in about the first 15 minutes of the big bang and were some 100 times bigger than our sun but they last only about a million years before exploding or turning into black holes.

By looking at what stars are made of it is possible to figure out how'recylced' the star is. Finding stars with very little metal for example would suggest they could be made of the first hydrogen produced after the big bang.

reference: First stars found? Not yet. -Astronomy.com

 

 

The cultural history of stars.

The cultural history of stars is about the historic personalities involved in the discovery of stars and theories about stars.

The idea that stars are like our own sun but just very far away came from came from a Greek philosopher Anaxagoras in about 450 BC. Later is was also Another Greek called Aristarchus of Samos, around 220 BC then in AD 1590, Giordano Bruno suggested the same thing but was burnt at the stake for the suggestion.

further reading and reference: Stanford Solar Center

It was around 1860-63 A.D, England, that the beginning of spectral analysis of stars was developed and explored by Sir William Huggins (1824-1910)

The idea that stars like our sun were big fusion reactions was proposed by Sir Arthur Eddington (1882-1944).

 

What

Why

News

How

History

Future

 


The future of stars?

Will stars last forever? Well stars go through cycles of being formed, burning and dying.

There are several ways in which stars can end up and it all depends on how much mass they ended up with at the beginning.

Some stars...

  • just expand out their outer layers and leave a dwarf star that slowly fades away.
  • explode and leave behind a dense core that slowly fades away.
  • stars explode but end up with a core so dense that light can't escape and produce a black hole.

 

 

In principle the stars will eventually go out but this is so far into the future it is hard to comprehend. It is some 10 trillion, trillion years. It ends in a time called "The Dark Era" in which only basic particles are left cruising around.

Although some astrophysical theories suggest that universes may be being formed regularly producing new big bangs. Superstring theory and M-Theories are the leading contenders.

In essence the universe is thought to be born with stars and die with stars.

Reference: Deep Time/Space - PBS

What

Why

News

How

History

Future

 


we welcome your suggestions & feedback


Comments on this web page to: info@clearlyexplained.com

©2000-2005 R.Conan-Davies.