The solar System...
...is made up of the sun (a star) and the 9 planets. Orbits are the paths the planets move around the sun they are slightly elliptical (squashed circles)
Our Sun is one of many billions of stars in the Milky Way. The Milky Way is just one galaxy of many millions of galaxies in the Universe.
A light year is the distance travelled by light in one Earth year.
Mass- is the measure of how much material there is in an orbit. The units are grams and kilograms/
Weight-is a measure of the force exerted on a mass due to the pull of gravity. The units are Newtons N .
Gravitational field strength- is measured in newtons per kilogram. On the earth the field stregnth is 10N/Kg. It varies to that on the moon.
Acceleration of free-fall refers to the greatest acceleration that a mass can achieve when it falls in a gravitational field. Its measured in metres per second per second.
Space is VERY COLD! The temperature depends on the distance from the sun.
Astronauts are exposed to harmful radiation whilst in space. Water is a good shield and scienstist are looking at surround air craft with water tanks.
Every action has an equal and oppisite reaction. - Spacecraft engines rely on this principle.
Escape velocity- when omething is thrown fast to escape the earths pull.
Black hole- smallest and most dense known object.- with an escape velocity of more than speed of light.
There are two ways of looking for intelligent life in the Universe:
- sending spaceships out to collect and return data
- searching for radio signals
A planet must past these tests before bing considered stable for life
- main sequence-
- right temperature
- stable conditions
- right age
- heavy elements
Unmanned space cratfs are used in space exploration as ;
- long journey
- equipment is just as effective
Theories and stars...
Steady state theory- many people believe that the universe had no beginning and would never end. Not many believe this now.
Big Bang Theory- is a scientific theory that the world was created from an explosion from a massively dense object.
Missing mass- hard to calculate dark matter
Asteroids-are a band of rock debris found between the orbits of jupiter and mars
Comets- have a core of frozen gas and dust.
Stars do not last forever, our sun is small to an avergae sized star,
Stars are made from nebula (clouds of dust and gases) pulled together by gravity.
A star the size of the sun becomes a red giant
It continues to cool before coming a white dwarf then a black dwarf.
A star much bigger than the sun becomes a red super giant. It shrinks rapidly and explodes releasing alot of energy. This is a supernova.
The dust will form new stars amd the remains will be either a neutron star or a black hole.