What makes a star twinkle?
A star twinkles because of aberrations of the light due to our atmosphere. Any time light travels between two different phases of matter, in this case space and the atmosphere, as well as air at different temperatures, the light is bent as well as changes speed. Depending on how the thermals are running, the light may travel between several different inter-phases before reaching the ground. By a different phase I mean two volumes of differing density. This is the prime reason for building the Hubble Space Telescope. Being in orbit, the light never travels through our atmosphere, thus it never has the twinkling, therefore Hubble can take much better pictures at much better resolution than ground based telescopes. There are new ground based telescopes that can now flex the mirror to remove the atmospheric aberrations, and thus can get nearly Hubble quality photos. Below is a link.
On the next clear night look at a bright star. * How many blinks does it make in 10 seconds? * Look at the moon, an airplane or a bright planet at night. Do these objects twinkle? A star is a point of light. It is so far away that even the largest telescope cannot show the star’s disk. The atmosphere changing between the star and your eye causes starlight to twinkle. Make these predictions about twinkling: a. Do stars lower in the sky or higher, twinkle more? b. Do stars twinkle more on a windy night, or a still night? c. Do stars twinkle more at sea level or on a mountain top? d. Do stars also change color as they twinkle? Hint: Count star blink rates to answer the first question. Share your data with students in other locations to answer the remaining questions. “Seeing” is the term astronomers use to describe the steadiness of images. “Seeing” is best when the twinkling is least. When the seeing is good, astronomers can collect better data about the brightness and color of distant s
