Why do star

Because all the light is coming from a single point, its path is highly susceptible to atmospheric interference i. 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.

Star wheels will help you find your way among the twinkling constellations, and you can trace the appearance of the planets along the ecliptic with a Skygazer's Almanac. I had a random thought, maybe someone out there has a better idea. Another reason stars twinkle might be because of objects traveling in the lights path. With this sort of occurance happening randomly every minute, every second. We could possibly looking at a very busy space, instead of the predictable space we know now.

Log in to Reply. Interesting line of thought. It was proposed that stellar scintillation, could be due to the turbulence in the Oort cloud, the great envelope of debris and pristine stellar mass surrounding the solar system. This could very conveniently also explain why planets, moon, satellite do not scintillate.

Because they are within the Oort cloud! Our atmosphere reaches about 10,km up from the surface of the Earth, and within the atmosphere air gets blown around, while hot air rises and mixes with cooler air. Stars appear to twinkle because as light from those stars passes through our atmosphere, it is bent and distorted by varying temperatures and densities of air.

This is the astronomical term for those quick changes in the apparent brightness of a star more on this in our guide to stellar magnitude or even the colour of a star produced by the aforementioned atmospheric irregularities. Similar effects are seen in the way our view of an object might be distorted by heat rising from a hot radiator or roaring fire, for example. It is possible to capture these effects of atmospheric distortion in an image, by photographing the changing colours of a twinkling star.

For more basic stellar astrophotography, read our guide on how to photograph the stars. For most people, the concept of a twinkling star is quite romantic, and conjures up memories of one of the most famous nursery rhymes of all time. The regions of gas and dust are called molecular clouds , because of their content. Molecular clouds are made of a mix of atoms, molecules, and dust.

Atoms are the small building blocks of all the stuff around us. Molecules consist of two or more atoms joined together. The molecules present in molecular clouds are typically molecular hydrogen, H 2 , but can also be more complex molecules, such as methanol, which consists of six atoms, or water, which consists of three atoms. Dust grains are even larger clumps of matter and they can be up to a few millimeters in size, which is huge compared with atoms or molecules. Molecular clouds in the interstellar medium are large.

In fact, a single molecular cloud can be hundreds of thousands of times heavier than the Sun. Their volumes also vary: a molecular cloud can be the same size as, or many times bigger than, our entire solar system. These enormous molecular clouds undergo turbulent motion. This means that the gas and dust within the clouds do not stay in the same place as time passes. These substances move around in all directions, like children running around in a school yard.

This turbulent motion of the gas and dust distributes the atoms and molecules unevenly, so that some regions of the molecular cloud will have more matter in them than other regions Figure 1A. If the gas and dust pile up to a very high level in a certain region, that region starts to collapse due to the pull from its own gravity. The region is smaller than the molecular cloud and lives inside the molecular cloud. But, when gas and dust start to collapse in a region within the molecular cloud, it slowly heats up.

This is a consequence of a law of physics, which tells us that, when matter is squeezed together, the density of the matter will increase and the matter will start to heat up. When the collapsing region has reached a size of nearly 10, AU, it is called a pre-stellar core Figure 1B and is officially a star in-the-making. Also, this pre-stellar core will later become the interior core of the star. Over the next 50, years or so, the pre-stellar core contracts. This might sound like a long time, but on an astronomical timescale it is considered a fairly swift process compared, for instance, to the age of the Universe, which is almost 14 billion years.

The core contracts until it is around 1, AU Figure 1C. After 50, years has passed, the system will have formed a disk around the central core, and excess material will be ejected outward from the poles of the star.

A pole on a star is like those on the Earth, namely defined as the axis that the star spins around. In Figure 1C , you can see two fountain-like structures where this excess material is ejected.

These structures are called jets, and they obey the laws of physics. The random motion of the gas and dust that we described earlier, combined with the system's contraction as the pre-stellar core forms, will cause the whole system to rotate.