Stars and Constellation

• Star


  • massive of hot gas called plasma
  • ex: Sun - the nearest star to our planet and the only star in the solar system
• In reality, there are approximately 400 billion stars in our galaxy and there are about 170 billion galaxies.
• Despite this great number of stars in our galaxy, a person can see only about 3,000 stars on the average
• Basic characteristics of stars

  • color
  • surface temperature
  • brightness
  • size
  • mass
• Colors of stars

  • star color ranges from red to blue
  • a star's color is dependent on its surface temperature
  • hottest to coldest: blue, blue-white, yellow, orange, red
• Color of the stars from hottest to coldest

  • blue - hottest
  • blue-white
  • yellow
  • orange
  • red - coldest
• red - coldest


  ex: Antares

  3,000 K
• Orange

  Aldebaran

  4,000 k
• Yellow


  Sun

  6,000 K
• Blue-white


  Sirius

  10,000 K
• Blue


  hottest

  ex: Rigel

  25,000 K
• Cooler stars tend to be redder in color, while hotter stars are bluer.
• Color of the Sun

  • the sun is a mid-range star since its color is yellow
• Brightness of a star

  • the brightness of a star as seen from the Eart depends on two factors: distance and actually brightness of the star.
• Apparent magnitude/distance

  • star's brightness as een from Earth
• real brightness : absolute magnitude
• Absolute magnitude

  • the real brightness of a star irrespective of its distance from Earth
• Mass and weight are not the same
• Size of the star

  • Sirius appears larger to Rigel because its nearer to us.
• Mass of a star


  • an important predictor for many other characteristics, including how long it will live.
• More massive stars live shorter lifetimes than the less massive ones since they consume their nuclear fuel much faster.
• Constellation

  • a group of bright stars that appear to form a pattern
  • may appear close to each other, but they are actually light-years apart
  • the International Astronomical Union recognized 88 constellations within the celestial sphere
• Celestial Sphere

  • an imaginary sphere of a large unspecified size where the objects we can see in the sky are drawn or projected.
• Zodiac constellations

  • "zodiac" loosely translates to "circle of animals" or "circle of life" in Greek.
• Astronomy: science

  astrology: destiny
• Zodiac constellations


  • Sagittarius ( The Archer)
  • Capricornis ( The Sea-Goat)
  • Aquarius ( The Water- Bearer)
  • Pisces ( The Fishes)
  • Aries (The Ram)
  • Taurus (The Bull)
  • Gemini (The Twins)
  • Cancer ( The Crab)
  • Leo (The Lion)
  • Virgo (The Maiden)
  • Libra (The Scales)
  • Scorpius (The Scorpion)
  • Ophiuchus (The Snake Bearer)
• Astronomy

  • is the study of the universe and its contents outside of Earth's atmosphere.
• Astrology

  • attempts to study how those positions, motions and properties affect people and events on Earth.
• How are constellations named?

  Ancient constellations mostly come from Greek and Roman mythology, while the most of the constellations created more recently were named after scientific instruments and exotic animals.
• Circumpolar Constellations

  • constellations visible all year round
  • all circumpolar constellations are found near the celestial poles and, due to their proximity to the poles, they never disappear from view
  • Cassiopeia, Cepheus, Draco, Ursa Major, and Ursa Minor
• Ursa major

  
• Ursa Minor

  
• Cassiopeia

  
• Cepheus

  
• Lyra

  
• Aquila

  
• Canis Major

  
• Aries

  
• Taurus

  
• Gemini