MODULE 6

• The purpose of this module is to help you know more about star patterns called constellations
• This will provide you a better grasp on how the earth's position along its orbit is related to the constellations visible in the sky at different times of the year
• The module contains the following lessons

  • Lesson 1- Characteristics Stars and Constellations
  • Lesson 2- Constellations
• After going through this module, you are expected to show which constellations may be observed at different times of the year using models
• Specifically, you are expected to

  • describe stars and constellations
  • describe the apparent movement of the stars in the sky
  • explain why some constellations are not seen at certain months
• Star


  An astronomical object consisting of luminous spheroid of plasma held together by its own gravity
• Constellation


  A group of visible stars that form a pattern when viewed from earth
• The motion of the stars that you see over several weeks or months

  Is due to the earth orbiting the sun
• Stars appear to move from east to west in the night sky
• The Orion constellation indicates that the cold season is coming in the northern hemisphere
• We can see different parts of the sky at different times of the year

  Due to the revolution of the earth around the sun
• The Polaris constellation helps sailors navigate
• The Balatik constellation signifies the start of rainy season in the Philippines
• Constellations may only be visible during certain seasons


  Due to the earth's orbit around the sun
• A star begins as a gravitationally bounded system of stars called a galaxy
• A hot glowing ball of gases is called a star
• The study of stars is called astronomy
• Groups of stars that form patterns are called constellations
• Stars


  • They differ in color due to their temperature
  • Their brightness is related to their distance from earth
  • The sun is the brightest star from Earth because it is the closest
  • Stars have different chemical compositions
• A star is a large ball of glowing hot plasma in space held by its own gravity
• Star sizes

  • Neutron stars (20-40 km diameter)
  • White dwarf stars (similar to Earth's diameter of 12,742 km)
  • Super giants (more than 1500 times larger than the Sun)
• Star temperature

  Ranges from 2000 K to over 40,000 K, with the Sun at approximately 5,778 K
• Star color


  Indicates the star's temperature, with blue/blue-white stars being the hottest and red stars being the coolest
• Star brightness


  Depends on the star's composition and distance from Earth, measured in apparent magnitude (how bright from Earth) and absolute magnitude (brightness at a standard distance)
• Types of constellations

  • Circumpolar (visible year-round)
  • Zodiacal
  • Seasonal
• In the Philippines, constellations have local names such as Baha for Taurus, Pandawara for Pleiades, Balatik for Orion, Gibbang for Gemini, Malara for Canis Minor, Lepu for Aquila and Buwaya which signifies the start of the rainy season
• A star is a glowing ball of hot gas
• Stars are important as a source of energy, for navigation, and for telling time and seasons
• The Polaris constellation located on the North pole helps sailors in their navigation
• Difference in apparent and absolute magnitude


  Is primarily due to the star's distance from Earth
• A star's spectrum


  Tells us about its composition
• Big dipper


  Also known as Ursa Major
• The position of the constellations changed

  Due to the rotation of the Earth to its axis and its revolution around the sun
• How stars appear to move

  1. The star rises at the East and moves like the sun from West to East

  2. This apparent motion of stars in reference to an observer is caused by the rotation and revolution of the Earth
• Observed position of a constellation

  • Depends on the observer's location
  • Constellations in the northern hemisphere are not visible to observers in the southern hemisphere or vice versa
  • Observers near the equator will gradually see most of the constellations in the sky at different times of the year
• The Taurus constellation or Baha as it is named in the Philippines, signifies the clearing of the forest and is visible from December to February
• Ancient Filipinos use constellations to mark the beginning of different activities in agriculture
• Why did our ancestors used constellations to mark the beginning of different activities

  Because constellations signify change in season which help farmers decide what plants they will cultivate and when they harvest their crops. Constellations signify the occurrence of constellation in specific month.