Earth Day

Things that might surprise you about our planet

  1. We’re the third rock from the sun
    Our home, Earth, is the third planet from the sun and the only world known to support an atmosphere with free oxygen, oceans of liquid water on the surface, and — the big one — life. Earth is one of the four terrestrial planets: Like Mercury, Venus, and Mars, it is rocky on the surface.
  2. 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.
  3. The planet has a waistline.
    Mother Earth has a generous waistline: At the equator, the circumference of the globe is 24,901 miles (40,075 kilometers). Bonus fact: At the equator, you would weigh less than if standing at one of the poles.
  4. The planet moves around the sun
    Earth isn’t just spinning: It’s also moving around the sun at 67,000 miles (107,826 km) per hour.
  5. Earth is very 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. (The oldest known rocks on Earth, called the Nuvvuagittuq Belt are on the coast of the Hudson Bay in Northern Quebec, and dating back to 4.28 billion years ago, scientists estimate.)
  6. The planet is recycled
    The ground you’re walking on is recycled. Earth’s rock cycle transforms igneous rocks to sedimentary rocks to metamorphic rocks and back again. The cycle isn’t a perfect circle, but the basics work like this: Magma from deep in the Earth emerges and hardens into rock (that’s the igneous part). Tectonic processes uplift that rock to the surface, where erosion shaves bits off. These tiny fragments get deposited and buried, and the pressure from above compacts them into sedimentary rocks such as sandstone. If sedimentary rocks get buried even deeper, they “cook” into metamorphic rocks under lots of pressure and heat.
  7. Our moon quakes
    Earth’s moon looks rather dead and inactive. But in fact, moonquakes, or “earthquakes” on the moon, keep things just a bit shook up. Quakes on the moon are less common and less intense than those that shake Earth. According to USGS scientists, moonquakes seem to be related to tidal stresses associated with the varying distance between the Earth and moon.
  8. The hottest spot is in Libya
    The fiery award for Earth’s hottest spot goes to El Azizia, Libya, where temperature records from weather stations reveal it hit 136 degrees Fahrenheit (57.8 degrees Celsius) on Sept. 13, 1922, according to NASA Earth Observatory. There have likely been hotter locations beyond the network of weather stations. (The image was created from data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite.)
  9. The coldest place is in Antarctica
    It may come as no surprise that the coldest place on Earth can be found in Antarctica, but the chill factor is somewhat unbelievable. Winter temperatures there can drop below minus 100 degrees Fahrenheit (minus 73 degrees Celsius)
  10. Antarctica is an extreme continent
    The southern continent is a place of extremes, with the Antarctic ice cap containing some 70 percent of Earth’s fresh water and about 90 percent of its ice, even though it is only the fifth largest continent. Did you know Antarctica is actually considered a desert? Inner regions get just 2 inches (50 millimeters) of precipitation a year (typically as snow, of course).

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