Quiz

• Speaker: 'hi students welcome back to my estrang techie youtube channel today's video lesson is very interesting week 7 to 8 lesson for grade 9 science quarter 3 is all about constellation check out our learning objectives infer the characteristics of stars based on the characteristics of the sun infer that the arrangement of the stars in a group or constellation does not change observe that the position of a constellation changes in the course of a night and show which constellations may be observed at the different times of the year using models be excited to learn this lesson so what are you waiting for keep on watching [Music] twinkle when was the last time you've heard or recited this song or poem in grade school you studied about stars and perhaps one of the things that surprised you in school was your teacher's statement that our sun is a star that means that those little stars that twin collect diamonds in the sky are not really small they are powerful balls of flaming gases that emit electromagnetic waves in all directions are the stars same in size color or are they equally bright here are some of our questions about stars when we look at the sky we see thousands of stars in reality there are approximately 400 billion stars in our galaxies and there are about 170 million of galaxies sun is only about 150 million kilometers away and it takes only 8 minutes and 20 seconds for the sunlight to reach our world its diameter is about 1.4 kilometers 100 times of the earth but yet it is only a medium-sized star many other stars are much much bigger a star is a natural luminous body visible in the sky especially at night it is a huge sphere of very hot glowing gas stars are the most widely recognized astronomical objects and represent the most fundamental building blocks of galaxies a star can be defined by five basic characteristics namely brightness color surface temperature size and mass so let's talk about them one by one let's have first the brightness the brightness of a star depends upon its size and temperature a large star shines brighter than a small star a hot star shines brighter than a cool star on the other hand brightness of a star also related to the distance from the earth to the star a star's apparent brightness is the brightness you see from the earth a hot large star that is very far from earth does not look very bright a star's absolute brightness is the brightness the star would have if all stars were the same distance from earth now let us have color and temperature star color ranges from red to blue the color of the star indicates its surface temperature let us see this table that shows the surface temperature and the color of different nearby star including the sun sun is colored yellow and it has a 5 700 degree celsius surface temperature proxima centauri its color is red the surface temperature is 2300 degrees celsius epsilon iridani its color orange surface temperature 4600 degrees celsius vega color white surface temperature 9800 degrees celsius serious color white its surface temperature is 10 000 degrees celsius al-nilam its color is blue and its surface temperature is 27 000 degrees celsius as you can see the coldest stars appear red and the hottest star appear in blue color next we have size many of the stars in the skies are the same size as our sun or a medium-sized star white dwarf stars are about the size of the planet earth red giants and super giants are large enough to fill our solar system all the way to jupiter now let's have the mass stars have a life cycle that depends on the initial mass of the star low mass stars or small stars survive for billions of years this small stars die quietly and in their place a small white dwarf is left behind high mass stars or large stars survive for a'
• Low mass stars or small stars survive for billions of years
• This small stars die quietly and in their place a small white dwarf is left behind
• High mass stars or large stars survive for a
• Small stars die quietly and leave behind a small white dwarf
• High mass stars or large stars survive for a few million years
• Scientists believe that all stars came from huge clouds of gas and dust called nebulae
• Brightness of a star as observed from Earth relies upon


  Distance and the actual brightness or the absolute brightness of the star
• The more massive a star is, the hotter its surface
• Stars grouped together are called constellations
• Constellations are imaginary patterns of stars
• Stars that make up a constellation appear close to each other from Earth, but in reality, they may be very distant from one another
• Many constellations have names that can be traced back to early Babylonians and Greek civilizations
• Constellations have different names in various cultures
• Orion is a constellation known as the hunter
• Taurus is another constellation
• There are 88 constellations recognized by the International Astronomy Union (IAU)
• Zodiac signs are based on 12 constellations
• Constellations appear and disappear in the night sky throughout the year due to the Earth's revolution