Why stars twinkle + Rings of Saturn

There are some really simple questions in astronomy whose answers one may not know. (The funny thing is that many kids would be knowing them 🙂 )

So, here are two of them.

Q. Why do stars twinkle?

A. We all know Earth has an atmosphere; and also that these stars are very far from Earth, essentially appearing as point-sized objects in space. If there was no atmosphere, it would have been simple: the light from the stars would follow a straight line path.

But we do have an atmosphere. So, when the light from the stars reaches our eyes, it gets refracted many times while passing through the different layers of the atmosphere. The Earth’s atmosphere is also turbulent or windy. Hence, the images that we get of the star keep changing in number and position. And our eye interprets this as twinkling.

So, if there was no atmosphere, would there be no twinkling?

Right, there would be no twinking in that case.

You can see these photographs of a star from Earth, and from outer space to see the difference:
http://apod.nasa.gov/apod/ap000725.html and http://apod.nasa.gov/apod/ap990605.html.

So, why do planets not appear to twinkle? Simple. Planets are much closer to us. They appear far bigger to us than the stars. So, the change in change in number and position of the images of the planets caused by the refractions, is not enough for it to appear that the planet is twinkling.

Q. What are Saturn’s rings made of ?

A. Saturn has six main rings. Each of these is made of many smaller rings.

Are Saturn’s rings solid? No, they are not solid. They are made up of floating objects- ice , rocks and dust; with size ranging from tiny specks to the size of houses.

When were these rings formed? Some believe that these are as old as the planet itself, i.e. 4 billions years old. Another possibility is that these rings were formed later (some millions of years ago).

For more on this, see http://www.universetoday.com/guide-to-space/saturn/formation-of-saturns-rings/

and http://science.howstuffworks.com/rings-of-saturn.htm .


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