With a radius of 6371.4 kilometers, Earth is the fifth largest planet in our solar system, and it's the only one known for sure to have liquid water on its surface. Earth is also unique in terms of monikers. Every other solar system planet was named for a Greek or Roman deity, but for at least a thousand years, some cultures have described our world using the Germanic word “earth,” which means simply “the ground.”
Earth orbits the sun once every 365.25 days. Since our calendar years have only 365 days, we add an extra leap day every four years to account for the difference.
Though we can't feel it, Earth zooms through its orbit at an average velocity of 29.8 kilometers a second. During this circuit, our planet is an average of 150 million kilometers away from the sun, a distance that takes light about eight minutes to traverse. Astronomers define this distance as one astronomical unit (AU), a measure that serves as a handy cosmic yardstick.
Earth rotates on its axis every 23.9 hours, defining day and night for surface dwellers. This axis of rotation is tilted 23.4 degrees away from the plane of Earth's orbit around the sun, giving us seasons. Whichever hemisphere is tilted closer to the sun experiences summer, while the hemisphere tilted away gets winter. In the spring and fall, each hemisphere receives similar amounts of light. On two specific dates each year—called the equinoxes—both hemispheres get illuminated equally.
About 4.5 billion years ago, gravity coaxed Earth to form from the gaseous, dusty disk that surrounded our young sun. Over time, Earth's interior—which is made mostly of silicate rocks and metals—differentiated into four layers.
At the planet's heart lies the inner core, a solid sphere of iron and nickel that's 1221.5 kilometers wide and as hot as 5400 degrees celsius. The inner core is surrounded by the outer core, a 2250-kilometer-thick band of iron and nickel fluids. Beyond the outer core lies the mantle, a 2900-kilometer-thick layer of viscous molten rock on which Earth's outermost layer, the crust, rests. On land, the continental crust is an average of 30.5 kilometer thick, but the oceanic crust that forms the seafloor is thinner—about 5 kilometers thick—and denser.
Like Venus and Mars, Earth has mountains, valleys, and volcanoes. But unlike its rocky siblings, almost 70 percent of Earth's surface is covered in oceans of liquid water that average 4 kilometers deep. These bodies of water contain 97 percent of Earth's volcanoes and the mid-ocean ridge, a massive mountain range more than 64300 kilometers long.
Earth's crust and upper mantle are divided into massive plates that grind against each other in slow motion. As these plates collide, tear apart, or slide past each other, they give rise to our very active geology. Earthquakes rumble as these plates snag and slip past each other. Many volcanoes form as seafloor crust smashes into and slides beneath continental crust. When plates of continental crust collide, mountain ranges such as the Himalaya are pushed toward the skies.
Earth's atmosphere is 78 percent nitrogen, 21 percent oxygen, and one percent other gases such as carbon dioxide, water vapor, and argon. Much like a greenhouse, this blanket of gases absorbs and retains heat. On average, Earth's surface temperature is about 14 degrees celsius; without our atmosphere, it'd be zero degrees. In the last two centuries, humans have added enough greenhouse gases to the atmosphere to raise Earth's average temperature by 0.8 degrees celsius. This extra heat has altered Earth's weather patterns in many ways.
The atmosphere not only nourishes life on Earth, but it also protects it: It's thick enough that many meteorites burn up before impact from friction, and its gases—such as ozone—block DNA-damaging ultraviolet light from reaching the surface. But for all that our atmosphere does, it's surprisingly thin. Ninety percent of Earth's atmosphere lies within just 16 kilometers of the planet's surface.
We also enjoy protection from Earth's magnetic field, generated by our planet's rotation and its iron-nickel core. This teardrop-shaped field shields Earth from high-energy particles launched at us from the sun and elsewhere in the cosmos. But due to the field's structure, some particles get funneled to Earth's Poles and collide with our atmosphere, yielding aurorae, the natural fireworks show known by some as the northern lights.
We all know that North is, well, north—somewhere above Alaska—and south is down near the middle of Antarctica. That will always be true for the planet’s geographic poles, but it’s only intermittently true for the planet’s magnetic poles. Over the past 20 million years, the magnetic poles have flip-flopped every several hundred thousand years or so, which means that if you had a compass in hand about 800,000 years ago, it would tell you that north was in Antarctica.
The amount of money invested in nuclear test could be used to finance 8,000 hand pumps, giving villages across third world access to clean water.
Acidification of the ocean is the worst type of pollution. Oceans are becoming more acidic rue to green house emissions from fossil fuel.
Livestock waste majorly contributes tosoil pollution. During monsoon, water runs over the fields carrying dangerous bacteria from the livestock into the streams.
More than 100 pesticides in any medium- air, water or soil can cause birth defects, gene mutation and cancer.
There are more around 73 various kinds of pesticides in the groundwater, which is used as drinking water.
There are more than 500 million cars in the world and by 2030 the number will rise to 1 billion. This means pollution level will be more than double.
Major oil spillslike those in the Gulf of Mexico, is the the worst type of pollution due to consistent oil spills in the water body which spreads everywhere else.
House owners use chemicals that are 10 times more toxic per acre, than the amount used by the farmers.
Around 1000 children die in India every year due to diseases caused from thepolluted water.
In India, the Ganges water is gradually becoming septic, especially due to dumping of half burnt dead bodies and enshrouded babies.
88% of the children in Guiyu, China suffer from various respiratory diseases as the area they live in is a huge e-waste site.
Antarctica is the cleanest place on Earth protected by anti-pollution laws.
Scientific research has proven that carbon dioxide emissions are lowering the pH of the ocean and are acidifying them even more.
A single car generates half a ton of CO2and a NASA space shuttle releases 28 tons of C02.
Starbucks's Green Cup Initiativex
Americans buy more than 29 million bottles of water every year. Only 13% of these bottles arerecycledevery year.
Tsunami in Japan during the year 2011, has created a debris of 70 miles, which consists of cars, plastic, dead bodies and radioactive waste.
Cadmium is a dangerous pollutant that kills foetus’ sex organ cells. It is wide spread in many things that we eat and drink.
It takes only 5 days for a jet stream in Chine to carry the air pollution to the United States.
Pollution in China can change the weather in United States.
World Health Organization (WHO) estimates 6400 people die every year in Mexico due toair pollution.
A single person in United States produces 2 kilograms of garbage every day.
The UAE is one of the biggest waste producer and water consumer.
Every 1 million ton of oil that is shipped, approximately 1 ton from gets wasted in the form of spills.
Most of the hazardous pollutants that are discharged in the atmosphere each year are released to surface water, ground water, and land, combined.
Approximately 3 billion people without proper shelter and healthcare cook and heat their homes using open fires and leaky stoves, thus contributing more towards pollution andglobal warming.
Chronic obstructive respiratory disease (COPD) that develop due to indoor air pollution is responsible for the death of more than 1 million people every year.
The people more susceptible to high ozone levels are children, elderly, people with lung disease, and people who are active outdoors.
A glass that is produced fromrecycled glassinstead of raw materials can reduce related air pollution by 20%, and water pollution by 50%.
If you think that you don’t smoke and you will be spared by lung cancer, just remember that your lungs or heart may be similarly damaged simply fromexposure to ozoneand particulate matter.
Places which are near to high traffic roads, seaports or railyards are dangerous place to live or work as they contain more concentrated levels of air pollution.
In cities, where there is huge traffic and vehicles run bumper-to-bumper, the pollutants in the air can seep into your car making the air you breathe inside your car up to 10 times more polluted than typical city air.
In 1987, the U.S. released 1.2 million tons of toxic chemicals into our atmosphere, 670,000 tons into our soil, and 250,000 tons into our water. (International Wildlife magazine)
In the US, 41% of all insecticides are used on corn. Eighty per cent of these are used to treat a pest that could be controlled simply by rotating the corn for one year with any other crop.
Public transportationand car pooling can help you to reduce air pollution and save money up to a great extent.
What can we do???
Find out more about how can we all change simple habits that can help to reduce polution and in some cases reverse it.