Blue light is scattered in all directions by the tiny molecules of air in Earth's atmosphere. Blue is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time. Closer to the horizon, the sky fades to a lighter blue or white.
Gases in the atmosphere like carbon dioxide, methane and water vapour trap some of the heat from the sun's rays, which would otherwise go back out into space. This keeps the Earth at a comfortable temperature, and prevents it getting too cold – like a giant greenhouse.
The ozone layer in the stratosphere shields life on Earth from most UV-B and UV-C, the most harmful varieties of ultraviolet radiation.
Ten Simple Things You Can Do to Help Protect the Earth
- Reduce, reuse, and recycle. Cut down on what you throw away.
- Volunteer. Volunteer for cleanups in your community.
- Educate.
- Conserve water.
- Choose sustainable.
- Shop wisely.
- Use long-lasting light bulbs.
- Plant a tree.
During sunrise and sunset the sun is low in the sky, and it transmits light through the thickest part of the atmosphere. A red sky suggests an atmosphere loaded with dust and moisture particles. We see the red, because red wavelengths (the longest in the color spectrum) are breaking through the atmosphere.
Astronomers estimate there are about 100 thousand million stars in the Milky Way alone. Outside that, there are millions upon millions of other galaxies also!
The sky can be full of water. But most of the time you can't see the water. They have turned into a gas called water vapor. As the water vapor goes higher in the sky, the air gets cooler.
As light from a star races through our atmosphere, it bounces and bumps through the different layers, bending the light before you see it. Since the hot and cold layers of air keep moving, the bending of the light changes too, which causes the star's appearance to wobble or twinkle.
Our sky is actually purplePurple light has higher energy, and gets scattered more than blue. But the answer to why we see blue skies isn't a matter of physics; it's an answer for physiology. Think back to high school biology. Ever done an eyeball dissection? (If not, we sometimes offer that at the Museum!
At sunset the light from the sun grazes across the surface of the earth, passing through a long column or pathlength of atmosphere. During its passage through the atmosphere the blue components of the light are reduced in intensity, making the transmitted beam of sunlight more yellow or even red in colour.
Well when the sun sets, it is lower down and the light has further to travel. Light is made up of all different colours - that's why we get rainbows. Blue light can't travel very far so much of it 'scatters' out before it reaches us. But red light can, which is why the sky appears more red and pink than usual.
Clouds are white because light from the Sun is white. As light passes through a cloud, it interacts with the water droplets, which are much bigger than the atmospheric particles that exist in the sky.
Thus, as sunlight of all colors passes through air, the blue part causes charged particles to oscillate faster than does the red part. More of the sunlight entering the atmosphere is blue than violet, however, and our eyes are somewhat more sensitive to blue light than to violet light, so the sky appears blue.
Mesopotamian religionThe concept of seven heavens as developed in ancient Mesopotamia symbolised both physical and metaphysical concepts.
The horizon is the line that separates the Earth from the sky. The astronomical horizon and true horizon are celestial horizons. Earth-Sky Horizons. The local horizon, also called the geometrical horizon, is the visible boundary between the Earth and sky.
Below that is the home of mid-level clouds, which generally occur between 6,000 and 25,000 feet. Finally, closest to Earth's surface are low clouds, which hover at or below 6,500 feet.
Astrology purports that astronomical bodies have influence on people's lives beyond basic weather patterns, depending on their birth date. This claim is scientifically false. Numerous scientific studies have disproven that astronomical bodies affect people's lives according to their birth date.
Top 10 cool things about stars
- Every star you see in the night sky is bigger and brighter than our sun.
- You can't see millions of stars on a dark night.
- Red hot and cool ice blue – NOT!
- Stars are black bodies.
- There are no green stars.
- Our sun is a green star.
- Our sun is a dwarf star.
- Stars don't twinkle.
Historically, stars have been important to civilizations throughout the world. They have been part of religious practices and used for celestial navigation and orientation. Many ancient astronomers believed that stars were permanently affixed to a heavenly sphere and that they were immutable.
Stars shine because they are extremely hot (which is why fire gives off light — because it is hot). The source of their energy is nuclear reactions going on deep inside the stars. In most stars, like our sun, hydrogen is being converted into helium, a process which gives off energy that heats the star.
Stars are huge celestial bodies made mostly of hydrogen and helium that produce light and heat from the churning nuclear forges inside their cores. Aside from our sun, the dots of light we see in the sky are all light-years from Earth.
Stars typically form in the midst of huge gas clouds. The force of gravity squeezes the gas until it is compressed enough to start the nuclear fusion process that fuels stars. Newborn stars are constantly balancing two opposite forcesas they grow. "This corralling of dense gas can give birth to new, high-mass stars."
A star is born when atoms of light elements are squeezed under enough pressure for their nuclei to undergo fusion. All stars are the result of a balance of forces: the force of gravity compresses atoms in interstellar gas until the fusion reactions begin.
