Earth is covered in seas
The oceans cover some 70 percent of Earth's surface, yet humans have only explored about 5 percent, meaning 95 percent of the planet's vast seas have never been seen.
And this is fascinating: Some 300 million years ago, there was just one continent, a massive supercontinent called Pangaea. And thus there was just one giant sea, called Panthalassa.
The planet is filled with riches
And these vast seas are rich, holding more than 20 million tons of gold. But don't grab your mining hat just yet, the metal is so dilute that each liter of seawater contains, on average, about 13 billionths of a gram of gold. Undissolved gold is also tucked away in rocks on the seafloor, and though there's not efficient way of getting at that precious metal, according to NOAA, if we could extract all of it, each person on Earth could have 9 pounds of the shiny stuff.
The next fact is truly cosmic. Read on!
Earth is covered with cosmic dust
Every day our planet is sprinkled with fairy dust … or dust from the heavens. On a daily basis, about 100 tons of interplanetary material (mostly in the form of dust) drifts down to the Earth's surface. The tiniest particles are released by comets as their ices vaporize near the sun. (Shown here, a Hubble Space Telescope close-up image of part of NGC 7023, or the Iris Nebula, showing the area is clogged with cosmic dust.)
We trek around a star
The Earth is approximately 93 million miles (150 million kilometers) from the sun. At this distance, it takes about 8 minutes and 19 seconds for sunlight to reach our planet.
Something once collided with the moon
Many researchers think some large object crashed into Earth long ago, and the resulting debris coalesced to form our moon. It is unclear though if that colliding object was a planet, asteroid or comet, with some scientists thinking a Mars-size hypothetical world named Theia was the instigator.
There was once a supercontinent
The Earth's continents are thought to have collided to become supercontinents and broken apart again several times in Earth's 4.5 billion year history. The most recent supercontinent was Pangaea, which began to break apart about 200 million years ago; the landmasses that comprised Pangaea eventually wandered into the current configuration of continents.
Shifting rocks created mountains
While the shifting slabs of rocks called tectonic plates are unseen to us, some of their effects are monumental. Take the Himalayas, which stretch 1,800 miles (2,900 km) along the border between India and Tibet. This immense mountain range began to form between 40 million and 50 million years ago, when India and Eurasia, driven by plate movement, collided. The tectonic crash led to the jagged Himalayan peaks.
Kilauea is the most active volcano
Hawaii's Kilauea volcano does pop its top rather frequently, it's not Earth's most active erupter. That title goes to the Stromboli Volcano, off the west coast of southern Italy, which has been erupting nearly continuously for over 2,000 years, according to the U.S. Geological Survey. Its spectacular incandescent explosions have earned it the moniker "Lighthouse of the Mediterranean."
There was a super-colossal eruption
The largest volcanic eruption recorded by humans occurred in April 1815, the peak of the explosion of Mount Tambora. The eruption ranked 7 (or "super-colossal") on the Volcanic Explosivity Index (VEI), which goes from 1 to 8 and is somewhat akin to the magnitude scale for earthquakes. The explosion is said to have been so loud it was heard on Sumatra Island, more than 1,200 miles (1,930 km) away. The death toll from the eruption was estimated at 71,000 people, and clouds of heavy ash descended on many far-away islands. [The 10 Biggest Volcanic Eruptions in History]
Our coastlines are crowded
Coastlines cover about 20 percent of U.S. land area (not including Alaska), and are home to more than 50 percent of the U.S. population, according to the National Oceanic and Atmospheric Administration (NOAA).