Black Holes and the Big Bang Theory

Black holes (picture on left) - are theorized to form when a massive star collapses at the end of its life. Centers of galaxies contain black holes. The gravitational field of a black hole is so great that not even light can escape from a black hole.

Big Bang Theory- the theory that proposes the Universe originated from a state of high temperature and density. This theory says the Universe began about 13.75 billion years ago. One piece of evidence of the Big Bang theory is the existence of cosmic background radiation (top picture). This radiation, from all directions in the sky, is said to be left over from the big bang.

Milky Way Galaxy

The Milky Way is the galaxy which contains our Sun. Our Sun is located within one of the spiral arms. Our galaxy is a collection of stars and interstellar dust. This dust/matter known as a nebula is the birthplace of stars. gravity is the force which pulls this matter together.
The average distance between stars in our part of the galaxy is 5 light-years. A light-year measures distances between interstellar objects (the distance light travels in one year).

Lenses

The two basic types of lens are pictured to the left. Top lens is a convex ( converging lens). Bottom lens is a concave (diverging lens).


Convex lens- magnifies, enlarges, image is inverted.




Concave lens- diverging, spreads light apart, image is reduced.

Diffraction

Diffraction- the slight bending of a wave around the edge of an obstacle in its path.

H-R Diagram

The Hertzsprung-Russell (H-R) diagram shows the relationship between temperature and absolute magnitude.

• 90% of all stars are main sequence stars
• blue stars have the highest surface temperatures
• the brightest main-sequence stars are also the hottest.
• the Sun is an average main sequence star, yellow in color
• as our Sun ages it will eventually become a red giant
• the Sun has an absolute magnitude of +5
  

Our Sun

Our Sun and solar system was formed from a huge cloud of dust and gases that condensed due to the force of gravity.
Scientists by studying the Sun's or any star's spectrum can determine the chemical composition of that star. Our Sun is composed of 71% hydrogen, 27% helium and 2% heavier elements.

The Sun's energy is produced by nuclear fusion. This process combines, fuses, hydrogen atoms into helium atoms. Some mass is lost during this process and transformed into energy. This energy is radiated into space as the EM spectrum and the solar wind.

The solar wind is a stream of electrons and protons which are emitted from the Sun's corona. The corona is the outer gas layer of the Sun seen during solar eclipses.

The Sun is a large nuclear fusion reactor that has enough fuel, hydrogen, to burn for approximately another 5.5 billion years. Our Sun like all stars will eventually run out of fuel, hydrogen, and collapse.

Doppler Effect Sound and Light

www.exploratorium.edu/origins/hubble/tools/doppler.html

Check this link about the Doppler effect.