Earth

Earth is a squashed sphere

Earth is not a perfect sphere. As Earth spins, gravity points toward the center of our planet (assuming for explanation's sake that Earth is a perfect sphere), and a centrifugal force pushes outward. But since this gravity-opposing force acts perpendicular to the axis of Earth, and Earth's axis is tilted, centrifugal force at the equator is not exactly opposed to gravity. This imbalance adds up at the equator, where gravity pushes extra masses of water and earth into a bulge, or "spare tire" around our planet.

Earth is on the move

You may feel like you're standing still, but you're actually moving — fast. Depending on where you are on the globe, you could be spinning through space at just over 1,000 miles per hour. People on the equator move the fastest, while someone standing on the North or South Pole would be perfectly still. (Imagine a basketball spinning on your finger. A random point on the ball's equator has farther to go in a single spin as a point near your finger. Thus, the point on the equator is moving faster.)

And, as you'll learn on the next slide, we're also racing around the sun at an incredible speed.

Earth is old

Researchers calculate the age of the Earth by dating both the oldest rocks on the planet and meteorites that have been discovered on Earth (meteorites and Earth formed at the same time, when the solar system was forming). Their findings? Earth is about 4.54 billion years old.

(Photo shown here, what may be the oldest known rocks on Earth, called the Nuvvuagittuq Belt on the coast of the Hudson Bay in Northern Quebec, and dating back to 4.28 billion years ago, scientists estimate.)

The driest place on Earth

Ironically, the driest place in the world — the Atacama Desert in northern Chile — is next to the biggest body of water — the Pacific Ocean. Average annual rainfall in Arica, Chile, is just 0.8 millimeters (0.03 inches). It is believed that Atacama's Calama city saw no rain for 400 years until a sudden storm fell in 1972. Unlike most deserts, the Atacama is relatively cold and, in its most arid parts, does not even host cyanobacteria — green photosynthetic microorganisms that live in rocks or under stones. NASA astrobiologies travel to the Atacama to look for microorganisms that live in such an extreme environment, hoping to learn how life might exist on other planets.

Coral reefs are the largest living structures

Coral reefs support the most species per unit area of the planet's ecosystems, rivaling rain forests. And while they are made up of tiny coral polyps, together coral reefs are the largest living structures on Earth — a community of connected organisms — with some visible even from space, according to NOAA.

We're losing fresh water

As the climate changes, glaciers are retreating and contributing to rising sea levels. It turns out that one particular glacier range is contributing a whopping 10 percent of all the meltwater in the world. That honor belongs to the Canadian Arctic, which lost a volume equivalent to 75 percent of Lake Erie between 2004 and 2009.

Climate regulation: The natural world helps regulate the Earth’s climate. Ecosystems such as rainforests, peatlands, and mangroves store significant amounts of carbon, while the ocean captures massive amounts of carbon through phytoplankton. While regulating greenhouse gases are imperative in the age of climate change, new research is showing that the world’s ecosystems may also play a role in weather. A recent study found that the Amazon rainforest acted as its own ‘bioreactor’, producing clouds and precipitation through the abundance of plant materials in the forest.

Economy: In the common tension viewed between the economy and the environment—e.g. do we clear-cut a forest or conserve it?—one fact is often neglected: the environment underpins the entire global economy. Without fertile soils, clean drinking water, healthy forests, and a stable climate, the world’s economy would face disaster. By imperiling our environment, we imperil the economy. According to research published in Science, the global worth of total ecosystem services could run between $40-60 trillion a year.

Health: Recent research has found what nature-lovers have long expected: spending time in a green space, such as a park, provides benefits for one’s mental and physical health. Exercising in a park, instead of inside a gym, has shown to provide mental health benefits as a greater sense of well-being. Walking for 20 minutes in a green space has been proven to help children with ADHD improve their concentration, even working as well, or better, than medication. People who live in more natural settings have better overall health, even when research has taken into account economic differences.