Do the stars twinkle?

We know that stars emit their own light. The twinkling of a star is due to the atmospheric refraction of star light. This can be explained as follows :

When the light coming from a star enters the earth's atmosphere, it undergoes refraction due to the varing optical densities of air at various altitudes. The atmosphere is continuously changing due to which it refracts the light from the stars by different amounts from one moment to the next. When the atmosphere refracts more star-light towards us, the star appears to be bright and when the atmosphere refracts less star-light, then the star appears to be dim. In this way, the star-light reaching our eyes increases and decreases continuously due to atmospheric refraction. And the star appears to twinkle at the night.


The scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation). Stars twinkle when we see them from the Earth's surface because we are viewing them through thick layers of turbulent (moving) air in the earth's atmosphere.

Stars (except for the Sun) appear as tiny dots in the sky; as their light travels through the many layers of the Earth's atmosphere, the light of the star is bent (refracted) many times and in random directions (light is bent when it hits a change in density - like a pocket of cold air or hot air). This random refraction results in the star winking out (it looks as though the star moves a bit, and our eye interprets this as twinkling).

Stars closer to the horizon appear to twinkle more than stars that are overhead - this is because the light of stars near the horizon has to travel through more air than the light of stars overhead and so is subject to more refraction. Also, planets do not usually twinkle, because they are so close to us; they appear big enough that the twinkling is not noticeable (except when the air is extremely turbulent).

Stars would not appear to twinkle if we viewed them from outer space (or from a planet/moon that didn't have an atmosphere).


Stars (except for Betelgeuse) are points of light. That is to say that although they can be very large their surfaces nor their size can be detected in angle of arc.

I.E. our sun measures about O.5 degree of arc angle (30 arcminutes); the moon about the same. Stars, mostly being millions or billions of times more distant than our own sun are only seen as brilliant points of light.

The perceived light from a star -(might therefore)- be more perceptible as blinking from atmospheric disturbances than are planetary light sources reflected to us by an actual visual surface of easily measurable angle of arc.

For instance some planetary surface sizes: Jupiter measures commonly at 45 arc seconds (0.75 arcminute) and Mars measures commonly at 22 arc seconds (0.36 arcminute).

An actual planet's surface, of measurable size might appear to shine with a steadier light, less diffused by atmospherics than a virtually infinitely small point of light like a star.

For a size comparison the supergiant star Betelgeuse, at 427 light years has a measured angular diameter of 0.044 arcsecond or 0.00073 arcminute.

Stars don't twinkle, stars are just humongous balls of gases at high temperatures. The twinkling effect is caused by the Earth's atmosphere. When the light from distant stars reach earth, their light gets bent on different angles because of the difference in air density in atmosphere , and the constant movement of air in atmosphere shifts the rays. This is the reason for the twinkling effect seen by us. And the scientific name given to it is stellar scintillation.

The stars are not really twinkling, they only seem to be twinkling.

We know that those stars are millions of light years away from us. All the distractions on the path of the light can cause a twinkling effect. Also when they reaches our earth, our atmosphere's refraction, blowing winds, pressure variations and temperature variations make them blink when we look, creating a twinkling effect

Also the stars that we see in the night sky are not in their actual positions. Because of refraction they seem to be in another position (in a small measure).

Refraction is just the phenomenon what we see when we look at an object at the other side of a glass beaker (magnified or change in position).

I don't know whether any recent discovery has proved it better, but I know that stars are no twinkling.

Stars are burning balls of hot gases which continuosly radiate heat and light of their own. To say that they twinkle would be incorrect because they are a constant source of light and do not stop emitting light till they die. But to us on earth it appears that they twinkle due to the refraction of the light we recieve from them causing these radiations to bent by the air molecules and particles present in the atmosphere.

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