Why do stars twinkle ...

Answer: On a clear, dark night, our eyes can see about 6,000 or so stars in the sky. They seem to twinkle, or change their brightness, all the time. In fact, most of the stars are shining with a steady light. The movement of air (sometimes called turbulence) in the atmosphere of Earth causes the starlight to get slightly bent as it travels from the distant star through the atmosphere down to us on the ground. This means that some of the light reaches us directly and some gets bent slightly away. To our eyes, this makes the star seem to twinkle. You will notice that stars closer to the horizon will appear to twinkle more than other stars. This is because there is a lot more atmosphere between you and a star near the horizon than between you and a star higher in the sky. Go out some night soon and have a look! Animated bowing Star Animated Star with blinking eyes Animated Star with cane and top hat Stars also do not blink their eyes (they don't have any!), tip their hats, nor take a bow!

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How stars are born and die Stellar evolution is a circle of life — dying stars spew their

contents into the galaxy, paving the way for the next generation. We live in a relatively quiet district of a galaxy 100,000 light-years across that contains around 200 billion stars arranged in a disk beset with spiral arms. As galaxies go, it’s pretty big, though the supermassive black hole at the center is relatively small, just 4 million solar masses. There is ample evidence from the Milky Way’s rotation that our galaxy, like all others, contains considerable dark matter, whose role in star formation eludes us. But many of the processes of stellar evolution have become apparent, most notably that through death comes life. Stellar evolution is cyclic, with new stars replacing those that pass away...

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