Plasma is formed in the stars because of very _______________.

The correct answer is high temperature.

Key Points

• Star: The celestial body which consists of a luminous sphere of plasma held together by its own gravitational field is called a star.
  • The Stars are classified by their spectrum and their temperature
  • Stars form a pattern in a group, which has a recognizable shape.
  • This group of stars is called a constellation.
  • At present, there are about 88 constellations.
  • Each constellation has been given a name according to its shape.
  • Some of the important constellations are Ursa Major, Ursa Minor, Orion, Leo Major, and Cassiopeia.
• The twinkling of a star is due to the atmospheric refraction of starlight.
• The starlight, on entering the earth’s atmosphere, undergoes refraction continuously before it reaches the earth.
• The atmospheric refraction occurs in a medium of gradually changing refractive index.
• Since the atmosphere bends starlight towards the normal, the apparent position of the star is slightly different from its actual position.

• When we rub a matchstick against the rough surface of a matchbox, then friction between the head of the matchstick and the rough side of the matchbox produces heat. This heat burns the chemicals present on the head of the matchstick due to which the matchstick lights up.
• A mirage is an optical phenomenon that creates the illusion of water and results from the refraction of light through a non-uniform medium.
• Mirages are most commonly observed on sunny days when driving down a roadway.
• As you drive down the roadway, there appears to be a puddle of water on the road several yards (maybe one hundred yards) in front of the car. Of course, when you arrive at the perceived location of the puddle, you recognize that the puddle is not there. Instead, the puddle of water appears to be another one-hundred yards in front of you.