constellation

• star - is a massive ball plasma that emits light
• the brightness of a star depends on its temperature and size
• two characteristics decine brightness: luminosity and magnitude
• luminosity - is the amount of light that a star radiates
• apparent magnitude - refers to itsits brightness as seen by an observer on earth
• absolute magnitude - indicates its true brightness, or the actual amount of light the star gives
• blue or blue white - 35 000° star
• white - 10 000° star
• red orange - 5 000° star
• yellow - 6 000° star
• red - 3 000° star
• supergiant - diameter is 1000 times compared toto that of the sun
• giant - diameter is 10 to 100 times that of the sun
• medium sized stars - diameter is one tenth to about 10 times the diameter of the sun
• white dwarf - diameter is about as massive as the sun, but a little more than half the diameter of earth
• neutron star - diameter is about 16 kilometers
• hydrogen - most common element in stars, it makes up 60 to 80 percent of the total mass of a star
• helium - second most common element in stars, which makes up about 20 to 40 percent of the mass of a star
• the large system of stars are called the milky way galaxy
• star cluster - group of stars
• two types of star clusters: globular cluster and open cluster
• globular cluster - are tight groups of hundreds of thousands of very old stars, gravitationally bound and arranged in a circular shape they contain 100000
• open cluster - are loosely clustered group of stars
• there are currently 88 recognized constellations
• big dipper are known as pointers
• eliptic - when the sun, moon, and planets follow a path along the celestial sphere, this path is tilted by 23.5°
• aquarius - january 20 to febuary 18
• pisces - febuary 19 to march 20
• aries - march 21 - april 19
• taurus - april 20 to may 20
• gemini - may 21 to june 21
• cancer - june 22 to july 22
• leo - july 23 to august 22
• virgo - august 23 to september 22
• libra - september 23 to october 23
• scorpio - octiber 24 to november 21
• sagittarius - november 22 to december 21
• capricorn - december 22 to january 19
• ophiuchus - 13th zodiac sign that has no traditional dates but its astronomical dates are november 30 to december 17