Scintillation

If you ever took time to look at the stars you may have wondered what causes them to seemingly twinkle. If you know about the composition of stars and how they work, you know that stars really don’t change luminescence that quickly. They tend to at a relatively constant level for extremely long periods of time. The only time that they have a major change is when the star gets older or is subjected to a major cosmic event such as passing near a black hole. So what makes stars twinkle? First off the phenomenon has a very official sounding scientific name called scintillation.

Scintillation is caused by a mixture of factors but they largely have to do with the point of view. A casual observer looking at stars in the night sky forgets that their view is different from looking at stars from space. The reason is that we have a huge invisible window in the form of our planet’s atmosphere. Think about it. The way things appear if you are looking at them without any obstructions and how they look for example through a piece of thick or distorted glass is different. That is because the light that passes through the glass is refracted and distorted before it reaches your eyes. This is the case when observing stars twinkling.

Our planet’s atmosphere is pretty turbulent. Just looking at the daily forecast will make you aware of the fact. In the case of the night sky even a clear night still distorts the star light that comes from space. This is what makes stars seem to twinkle. However it is not just the air in the atmosphere but other things like dust that cause the twinkling effect. Overall a shuttering effect is happening. If you seen cloud covered moon you see how the atmosphere can easily block light. This is what happens with stars. Dust and other debris stirred up by turbulence in our atmosphere pass in front our line of sight with the stars we observe causing them to twinkle.

The effect of scintillation shows one of the different challenges that astronomers must take into account when observing stars. They have to take into account such conditions in order to make accurate measurements and observations. Another example are how astronomers have misclassified celestial objects. A good exmaple is Alpha Centauri. This star seem like a single object to observers. However, the star is actually a binary system consisting of two different stars.

We have written many articles about scintillation for Universe Today. Here’s an article about the interstellar cloud of gas as a natural lens, and here’s an article about parallax.

If you’d like more info on scintillation, check out these articles from Wikipedia and Univ. of Florida: Astronomy.

We’ve also recorded an episode of Astronomy Cast all about the Hubble Space Telescope. Listen here, Episode 88: The Hubble Space Telescope.

Reference:
Astrophys-Assist

Tagged as: Astronomy, earth's atmosphere, scintillation