Why Do Stars Twinkle?
Changes in the Earth's atmosphere make stars appear to twinkle.
CREDIT: Mike Read (WFAU), UKIDSS/GPS and VVV
Stars twinkle because their light must pass through pockets of Earth's atmosphere that vary in temperature and density, and it's all very turbulent. On rough nights, a star appears to shift position constantly as its light is refracted this way and that.
It's much like watching a coin appear to dance at the bottom of a pool.
Astronomers try to overcome the twinkling by using adaptive optics, in which many small mirrors on the scope adjust constantly to allow for the atmospheric disturbances.
They can also use space-based telescopes to make observations. Telescopes orbiting Earth above the atmosphere avoid the problems caused by turbulence.
Planets, on the other hand, generally do not appear to twinkle. The planets of our solar system are much closer to Earth than the stars we see , so planets loom slightly larger within our field of vision (in reality, stars are actually much larger ). Because planets appear larger, the light reflecting from them is less shifted around by the pockets of air in the turbulent upper atmosphere, according to astronomer and blogger Phil Plait.
But the rule is not hard and fast — planets can appear to twinkle when the atmosphere is unusually turbulent.
Got a question? Email it to Life's Little Mysteries and we'll try to answer it. Due to the volume of questions, we unfortunately can’t reply individually, but we will publish answers to the most intriguing questions, so check back soon.
Life's Little Mysteries: Gift Edition Hardcover Book
Uncover the truth behind more than 100 mysteries that surround us every day with our new hardcover book! Perfect for gifts and classrooms, and suitable for all ages. Some of the included mysteries are:
- Why Do Cats Land on Their Feet?
- How Long Does it Take to Make Petrified Wood?
- What Everyday Things Around Us Are Radioactive?
Find out all of this and much, much more in our NEW hardcover book.
It makes a great gift idea for all ages. more info>>