As light travels from a distant star through the atmosphere and down to us on the ground, hot and cold air gets in the way and bounces it about. Some of the light reaches us directly, while others are distorted along the route. Our eyes interpret it as glittering because of its bendiness. The result is a shimmering effect when looking at the night sky.
The cause of this glow is actually not visible stars or planets, but instead it's all around us: the Earth. Light waves from the Sun reach our planet and after passing through it, they repeat some of their characteristics (such as color) which results in another type of light called "backscatter." This happens especially during sunset and sunrise when the Earth's shadow falls over different parts of it. Backscattered light forms bright and dark areas on the moon and sun, respectively.
The reason why this occurs is because light particles inside the air molecules move around in small circles when exposed to heat or cold. When this movement matches the frequency of visible light, rainbow-like colors are produced. These colors, which range from red to violet, depend on the height at which they are viewed - lower levels see deeper into the atmosphere where longer wavelengths are backscattered. - Source: Space.com.
The best time to observe this phenomenon is just before dawn or after dusk. Be sure to watch for several nights so you can see how often the moon goes through its phases.
When looking up in the night sky, you may observe that the stars flicker or sparkle; their light does not appear to be consistent. Instead, the light from stars is bent as it gets to your eyes by the Earth's atmosphere. This produces the illusion of sparkling. The flickering effect is due to the rapid movement of clouds across the face of the moon as they pass over it.
The atmosphere also affects the quality of the night sky: It filters out certain wavelengths of light, leaving only those visible to our eyes (red and orange). Blue light takes longer to reach the surface of the earth and so would not be seen from most places on earth. Green light takes even longer than blue, and so wouldn't be seen from most places on earth at all. White light takes about a quarter of a second to reach the surface of the earth, which is why we see with our eyes open during daytime hours - because almost no sunlight reaches the ground during the day!
Atmospheric effects also cause other celestial phenomena to appear in the night sky. For example, lightning is an electrical discharge through the atmosphere that creates its own unique set of behaviors in radio waves that can be detected on the ground by sensitive receivers.
Finally, the atmosphere allows for the viewing of objects beyond the planet's surface by blocking much of the heat radiation given off by the sun when it enters the atmosphere.
As light from a star travels through our atmosphere, it bounces and bumps across the various layers, distorting the light before it reaches you. Because the hot and cold layers of air continue to move, the bending of the light varies, causing the star's appearance to wobble or twinkle.
Stars appear bright because they are very distant; even at night, some of them are so far away that their light has had time to reach us. They also appear red because those nearest to us are giving off heat from their intense inner fires, while those further away are cool enough for their light to be blue instead of white or yellow.
The flow of air (also referred to as turbulence) in the Earth's atmosphere bends starlight as it travels from a distant star through the atmosphere to us on the ground. Some of the light reaches us straight, while some is somewhat distorted. The more gas and dust there is in the atmosphere, the more the starlight will be blurred when seen from earth.
Stars appear bright because they are very far away. Even though stars are so far away that their brightness fades greatly over distance, they still look very bright because we are always near enough to see them against the darkness of space. They seem even brighter against the background of the night sky because stars give off almost all wavelengths of light, including infrared and ultraviolet.
At least some part of every star is composed of hydrogen atoms fused together into larger molecules or elements. The most common element in the universe is hydrogen, which makes up 75% of the mass of the universe. So many stars are made out of hydrogen that it is by far the most common element in the cosmos.