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7 Science Questions


Why Is The Sky Blue?
The reason the sky looks blue is because of an effect called scattering. Sunlight has to pass through the Earth's atmosphere, which is filled with gases and particles that act like the bumpers on a pinball machine. They bounce sunlight all over the place! If you've ever held a prism in your hands, you know that sunlight is made up of many different colors, all of which have different wavelengths. Blue light has a short wavelength, so it gets through the filter more easily than colors with longer wavelengths. This means that blue light is scattered widely as it passes through the atmosphere. That's why the sky looks blue during the parts of the day when the Sun is high in the sky. At sunrise and sunset, the sun's rays have to travel a longer distance to reach you. That cancels out blue light's wavelength advantage and lets us see the other colors better. That’s why sunsets often look red, orange, or yellow!

How Old Is The Earth?
The Earth's age is something that people have been arguing about for a long time. Back in 1654, a scholar named John Lightfoot, said that the Earth had been created at exactly 9 a.m. on Oct. 26, 4004 B.C. In the late 1700s, a scientist named Comte de Buffon heated up a small replica of the planet that he had created. He then measured the rate at which it cooled, and based on that data, estimated that the Earth was about 75,000 years old. In the 1800s, the physicist Lord Kelvin used different equations to set the Earth's age at 20 to 40 million years. Modern day Earth scientists have used the knowledge of radioactivity to determine the age of the Earth's rocks. From that, they've been able to determine that the Earth formed about 4.54 billion years ago!

Will The Sun Ever Stop Shining?
In about 5.5 billion years, the sun will run out of the hydrogen in its core that it burns as fuel to create sunshine. Instead, it will start burning the hydrogen in its surrounding layers. That will be the start of the sun's death, in which its core will shrink and its outer layers will expand massively. This will turn the sun into a red giant. In a final burst, the sun will roast the solar system with a blast of heat. It will temporarily turn even the cold area of Pluto and the Kuiper Belt (the area past Neptune) into a sauna. It's likely that the inner planets, including Earth, will be either sucked into the dying giant, or else turned into cinders. But don’t worry! Unless humans manage to travel to the solar systems of other stars, nobody is going to be around to experience this final blaze. The sun, which is about halfway through its expected lifespan, is already gradually heating up. In a billion years from now, the sun is expected to be about 10% brighter than it is now.

How Do Magnets Work?
A magnet is any object or material that has a magnetic field. A magnetic field is a bunch of electrons flowing all around an object in the same direction. Electrons like to hook up in pairs, and iron has a lot of unpaired electrons that are all eager to get in on the action. So, objects that are solid iron or have a lot of iron in them are going to be pulled towards a powerful magnet. Nails are objects that have a lot of iron in them. Humans have known about the phenomenon of magnetism for a long time. There are naturally occurring magnets, but medieval travelers figured out how to rub steel compass needles against natural magnets too. This caused the compass needles to pick up electrons and became magnetized, which means that they developed their own magnetic fields. In the 20th century, researchers developed new materials and charging devices that allowed them to make more powerful permanent magnets. 
 
What Causes A Rainbow?
Rainbows are caused by the droplets of water that remain suspended in the atmosphere after a rainstorm. As sunlight hits them, the droplets act as tiny prisms and bend the light to break it up into wavelengths. The wavelengths are reflected back at us. That creates the arc with bands of colors of the visible spectrum that we see. Because the droplets have to reflect the light at us, we have to be standing with our backs to the sun. We also need to be looking up from the ground at an angle of about 40 degrees. If you're in an airplane and you see a rainbow from above, it actually may look like a circle, rather than an arc.

Why Are Bubbles Round?
Actually, bubbles are not always perfectly round all the time. You probably have noticed this if you've ever used a toy wand to blow soap bubbles. But bubbles want to be round, and if you blow one that's more tube-shaped, it struggles to reshape itself. That's because bubbles are thin layers of liquid whose molecules stick together because they are attracted to each other. This creates what we think of as surface tension. Surface tension is a barrier that resists objects trying to move through it. Inside the layer, air molecules that are trapped can't get out, even though they're pushing against the water. On the outside, more air is pushing inward. The best way for the liquid layer to resist those forces is to take the most compact shape, which happens to be round, like a ball.

What Are Clouds Made Of?
A cloud is made of water droplets, or ice crystals, or a mixture of both that is suspended above the Earth's surface. Clouds are formed when moist, warm air rises. As it rises higher and reaches a space that's cooler, the warm air cools down. This causes the water vapor to condense into tiny water droplets and/or ice crystals, depending on how cold they get. Those droplets and crystals stay together because they are attracted to each other. The result is a cloud. Some clouds are thicker than others because they happen to have more water droplets packed in close together. Clouds are a key part of our planet's water cycle, in which water continually moves between the surface and the atmosphere. Water changes from liquid to gas to liquid, and sometimes to solid as well. If it weren't for that cycle, there probably wouldn't be any life on our planet.