Everyone must be familiar with the famous poem : Twinkle Twinkle Little StarБ. Well, itБs not just a poemбfor children, itБs actually referring to a particular scientific phenomenon that has fascinated observers from manyбyears. They certainly appear to do so, Why do all the other stars in the night sky appear to twinkle, but Planet sбnever does? Why Do Stars Twinkle? Light from stars crosses a very long distance to reach us and also passes through EarthБs atmosphere, whichбvary in temperature and density. Our atmosphere is very turbulent, with streams and eddies forming, churning around, and dispersing all the time. Every layer of EarthБs atmosphere has air moving in different directions atбdifferent intensities.
When light from stars passes through the atmosphere, it is bent due to refraction, which is why stars seem to twinkle when we stare at them. If viewed from outer space, you would not see the stars twinkling.
Why do stars twinkle? Though it wouldnвt work so well in the nursery rhyme, a there is actually a technical term for when stars twinkle:В astronomical scintillation, an effect due to our planetвs atmosphere. As light travels through the blanket of air around our planet, it is diffracted (bounced around) causing a quick apparent dimming and brightening в a star\’s signature \”twinkle\”. While some stars do physically over time, they typically do so on long timescales в these changes sometimes over hours, but more often over days, weeks, or years.
These variable stars are well studied and often signal complex physical changes happening to the stars in question. The more rapid changes of scintillation, on the other hand, come about long after the light has left the star. Light waves traveling through Earthвs atmosphere diffract as they pass through pockets of air at different temperatures. Because the light waves come from a single point, this effect can make the starвs brightness and/or position appear to change. Why Don\’t Planets Twinkle Too? Unlike stars, planets don\’t twinkle. Stars are so distant that they appear as pinpoints of light in the night sky, even when viewed through a telescope.
Because all the light is coming from a single point, its path is highly susceptible to atmospheric interference (i. e. their light is easilyВ diffracted). The much closer planets appear instead as tiny disks in the sky (a distinction more easily discerned with a telescope than with the naked eye). Their apparent sizes are usually larger than the pockets of air that would distort their light, so the diffractions cancel out and the effects of astronomical scintillation are negligible. will help you find your way among the twinkling constellations, and you can trace the appearance of the planets along the ecliptic with a.