GALAXIES GRADE NINE SCIENCE
basic information on the galaxy
Galaxies contain at least 1 super massive black hole at its centre.
A black hole is a region of space where gravity is so strong that nothing, not even light can escape.
Its existence is very strong.
For example, at the centre of the milky way, a number of stars can be seen orbiting around q point in space that seems to have nothing in it. At this spot there is a black hole for certain.
The main way that a black hole affects its surroundings is through its tremendous gravitational pull.
Its gravity is so strong that it can pull a star right into it.
This completely destroys the star. However, the mass of the star adds to the black hole’s original mass, increasing size of the black hole. It has been estimated that the milky way’s black hole has been pulling stars in for 7 billion years.
The black hole has a mass equal to about 3 million stars that are of similar size of sun.
Astronomers speculate that galaxies had collided, the centre of each one gradually moves towards the others.
After 100 million years they will merge with their masses combining into a single super massive back hole.
PROPERTIES OF THE GLAxIES
In a galaxy it has stars planets and dust.
If a galaxy have more dust, it produces more new stars because stars form from dust and gases that present in nebulae.
Some galaxies thought to be very ancient because it has all been used to make the star.
The farthest galaxies we can see may be the oldest because the light has taken so long to reach us.
Gravity pulled the material together again, repeating cycle of the star formation, explosion and spreading new elements into space.
After the sun, the next nearest star is a group of three stars that orbit each other,which is caled cantauri system.
It lies about 4.3 ly awaay from the solar system. If you are talking to someone from one of those stars to the world, it would take a word 8.5 years. This is how long it would take the radial signal to reach.
A system with more than 2 or more stars is called binary system. If the stars close together it might be possible for planents like our orbit all the way around both of the,.
Sirus is brighter because it is different kind of star than the centauri stars, Sirus is about the mass of our sun. It is the brightest star that is visble from earth.