The scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation)
Stars (except for the Sun) appear as tiny dots in the sky
As their light travels through the many layers of the Earth's atmosphere, the light of the star is bent (refracted) many times and in random directions
This random refraction results in the star winking out (it looks as though the star moves a bit, and our eye interprets this as twinkling)
Characteristics of Stars Size: anywhere from 20km to 1 trillion km in diameter Mass: the amount of matter Color: stars can be red, blue, white, orange or yellow Composition: contain different elements determined using spectra
Characteristics of Stars Temperature: Blue is the hottest (35000 ° C) Red is the coolest (3000 ° C) Yellow (our sun) (5500°C)
Expressed as multiples of the mass of the sun—ONE SOLAR MASS
1 solar mass is approximately 2 X 10 30 or approximately 330,000 Earth masses
Solar Mass determines life stages of a star
Life Stages of Stars With Solar Masses less than 8 Solar Masses
Main Sequence Star (Our Sun) — >90% of all stars >The star is stable >Burns Hydrogen gas to Helium in its core through nuclear fusion > The energy released causes the star to shine. >Stars spend about 90% of their active lifetime as main sequence stars. Red Giant — >The star begins to run out of fuel and the core begins to shrink >Helium turns into Carbon >Rapid burning of helium causes outer layer to puff out, cooling the star >The star turns red
Planetary Nebula — >Outer layers are ejected as core continues to shrink >Shell of hot gas >Core is exposed White Dwarf — >Low mass core continues to shrink creating a white dwarf >Surrounded by the Planetary Nebula
There are several types of galaxies the three main ones are:
Spirals are easily identified by their main components. They are in the shape of a flat disk with a bright central nucleus and spiral arms that extend out from the nucleus.
Ellipticals are different from spirals in that they have very little (or no) gas and dust. They have only stars which are concentrated near their centers
Irregular galaxies have a chaotic appearance, with large clouds of gas and dust mixed with both old and young stars at random. They have no apparent spiral arms or nuclear bulge. Irregulars are generally faint. They make up probably about 25% of all galaxies.
Quasars : give off radio & X-waves. They are the most distant objects in space. Give off tremendous amounts of energy.
Quasars give off enormous amounts of energy - they can be a trillion times brighter than the Sun! Quasars are believed to produce their energy from massive black holes in the center of the galaxies in which the quasars are located. Because quasars are so bright, they drown out the light from all the other stars in the same galaxy.