How many computers are there in the world?

According to statistics from technology research companies such as Gartner Inc., in April 2002 the billionth personal computer (PC) was shipped. The second billion mark (some being ordered as replacements for older PCs) was reportedly reached in 2007. With personal computers becoming more popular around the world, research companies estimate that there will be more than two billion PCs in active use by 2015.

In the United States, more than half of the people who use a computer are also connected to the Internet.

Does organic farming contribute to less pollution?

Yes. Organic farmers also try to do more tasks using human power rather than gas-powered vehicles, thereby using less fuel and cutting down on pollution. Organic farms that raise livestock like dairy cows or chickens feed the animals with natural food, avoiding pollution-causing chemicals and growth hormones that make cows produce more milk and chickens produce more eggs.

Some organic farmers also allow their animals to roam in a large area (such animals are described as “free range”) rather than keeping them in small, climate-controlled pens for their entire lives.

How does an electric car work?

On the outside, most electric cars look exactly like gas-powered cars. An electric car does not have a tailpipe or a gas tank, but the overall structure is basically the same. Instead of a huge engine, an electric car uses an electric motor to convert electric energy stored in batteries into mechanical energy.

Different combinations of generating mechanisms—solar panels, generative braking, internal combustion engines driving a generator, fuel cells— and storage mechanisms are used in electric vehicles.

Is there a red planet?

Yes. Mars, the fourth planet from the Sun, is called the Red Planet. It looks red because the rocks on the surface contain rusted iron. It has an atmosphere with clouds, winds, and dust storms—its red dust floats in the atmosphere and gives the planet a red sky.

Mars, which has two moons, orbits the Sun every 687 days and rotates on its axis once every 24 hours and 37 minutes.

Why is nuclear power dangerous?

The good thing about fission-generated nuclear energy is that very little fuel is needed to produce huge amounts of energy. (Two pounds of nuclear fuel could produce as much energy as 6.5 million pounds of coal, for instance!) The challenging part is that the process must be very carefully controlled. (In a nuclear reactor, control rods that absorb neutrons are moved in and out of the core to control the process.) If it isn’t controlled, the result could be a build up of pressure within the reactor. If this continues, radioactive gases might be released along with steam. It was a situation like this that happened at the Chernobyl plant in the Soviet Union in 1986, resulting in radioactive pollution that still exists today. An uncontrolled nuclear reaction can cause harmful radioactive materials (such as iodine isotopes that can cause thyroid cancer) to be released into the environment. This by-product of nuclear fission is a problem connected with nuclear power. Nuclear reactors are encased in thick layers of steel and concrete to keep radiation from escaping.

And because leftover nuclear fuel is highly radioactive, it must be carefully stored far away from people for decades or even centuries before it is safe again. Transporting and disposing of dangerous waste is another challenge presented by nuclear power; at present, used fuel is sealed in safety containers and buried deep underground. The nuclear process that we get our power from is called fission, where atomic nuclei that break apart produce great energy and heat. But nuclear power can also be created by a process called fusion, where atomic nuclei join together. Scientists are still working on creating a satisfactory fusion reactor. The Sun produces its great energy and heat through the nuclear fusion of its hydrogen gases.

Why do insects have eyes with thousands of lenses?

Most adult insects, including bees and dragonflies, have two large compound eyes, made up of separate, sometimes thousands, of lenses. They all point in different directions to give the insect a very wide field of vision.

The lenses also help the insect see movement, enabling it to react quickly to seize its prey or escape danger. You can witness this yourself as you try to swat a fly in your home it’s almost impossible to catch a flying insect!

Which tree produces the largest nut?

The coco de mer tree, a palm that only grows today on two islands in the Seychelles, produces both the largest seed (each weighs about 44 pounds [20 kilograms]) and the largest nut in the world. The nut, which takes six to seven years to mature and another two years to germinate, is sometimes called the sea coconut or Seychelles nut. When early explorers first discovered the nut, they thought it came from a mythical tree at the bottom of the sea.

Sixteenth-century European nobles decorated the nut with jewels as collectibles for their private galleries. Today, the coco de mer is a rare protected species.

What is Earth Day?

Earth Day is a national holiday that was first celebrated on April 22, 1970. It was created by Senator Gaylord Nelson, a Democrat from Wisconsin who was elected to the U.S. Senate in 1962. Senator Nelson decided to set aside one day aside for the entire nation to focus on environmental issues, learn about ways to improve the environment, and protest against the federal government’s unwillingness to help solve problems such as air pollution and the widespread destruction of forests.

After lots of hard work and publicity, on the first Earth Day 20 million Americans gathered at different places from the East to West coasts to hear speeches, participate in community-wide cleanup efforts, and demonstrate to the government that the environment is a major national issue. Ever since then, April 22 has been the date for celebrating Earth Day—a time when the United States (and now many countries all over the world) could participate in educational activities that celebrate Earth and think of new ways to preserve our natural resources. On Earth Day 2008, over 100 million people joined in the effort to celebrate and protect our planet.

Why is the sky blue?

Violet and blue light have short waves which are scattered more than red light waves.

While red light goes almost straight through the atmosphere, blue and violet light are scattered by particles in the atmosphere. Thus, we see a blue sky.

When was the earliest programmable computer built?

In 1943 and 1944, the British government developed two Colossus computers. These huge machines were electronic computing devices used by British code breakers to read encrypted German messages during World War II. Dubbed “Colossus Mark 1” and “Colossus Mark 2” these devises were the world’s first programmable, digital, electronic, computing machines.

Based on concepts of the British mathematician Alan M. Turing, the mathematician Max Newman and engineer Tommy Flowers designed and built the machines, which used vacuum tubes (thermionic valves) to perform the calculations. The Colossus hardware and blueprints were destroyed as part of an effort to keep the project secret. However, based on notes in engineers’ logs and other information, in 2007 a functional replica of a Colossus computer was completed. The computer is on display at the Bletchley Park Museum in Milton Keynes, Buckinghamshire, England.