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50 interesting facts about Earth

31. Earth is covered in seas

Sea view

(Image credit: Getty Images)

The oceans cover some 70 percent of Earth's surface, according to NOAA (opens in new tab), yet humans have only explored or mapped about 20 percent, meaning most of the planet's vast seas have never been seen.

Some 300 million years ago, there was just one continent, a massive supercontinent called Pangaea. This means there was just one giant sea, called Panthalassa.

32. The planet is filled with riches

Gold nugget close up

(Image credit: Getty Images)

And these vast seas are rich, holding more than 20 million tons of gold, according to Forbes (opens in new tab). 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 no 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.

33. Earth is covered with cosmic dust

Stars in night sky

(Image credit: Getty Images)

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, according to Astronomy magazine (opens in new tab). The tiniest particles are released by comets as their ices vaporize near the sun. 

34. We trek around a star

Sun and Earth

(Image credit: Getty Images)

The Earth is approximately 93 million miles (150 million kilometers) from the sun, according to Space.com (opens in new tab). At this distance, it takes about 8 minutes and 19 seconds for sunlight to reach our planet.

35. Something once collided with the moon

Artist's conception of the hypothetical impact of Theia and young Earth.

(Image credit: NASA/GSFC)

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.

36. There was once a supercontinent

Pangaea

(Image credit: Getty Images)

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.

37. Shifting rocks created mountains

Mountains

(Image credit: NASA Earth Observatory.)

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, according to NASA (opens in new tab). 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, according to USGS (opens in new tab).

38. Kilauea is not the most active volcano

Kilauea volcano

(Image credit: Getty Images)

Kilauea is historically regarded as the most active volcano. But, while Hawaii's Kilauea volcano does pop its top rather frequently, it's not Earth's most active erupter. One that is more active iso 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 (opens in new tab). Its spectacular incandescent explosions have earned it the moniker "Lighthouse of the Mediterranean."

39. There was a super-colossal eruption

Tambora

(Image credit: NASA Earth Observatory)

The largest volcanic eruption recorded by humans occurred in April 1815, the peak of the explosion of Mount Tambora, according to NOAA (opens in new tab). 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, Live Science previously reported. The death toll from the eruption was estimated at 71,000 people, and clouds of heavy ash descended on many far-away islands. 

40. Our coastlines are crowded

American coast

(Image credit: Getty Images)

Coastlines cover about 20 percent of U.S. land area (not including Alaska), and are home to almost 40 percent of the U.S. population, according to NOAA (opens in new tab).

Ailsa is a staff writer for How It Works (opens in new tab) magazine, where she writes science, technology, history, space and environment features. Based in the U.K., she graduated from the University of Stirling (opens in new tab) with a BA (Hons) journalism degree. Previously, Ailsa has written for Cardiff Times magazine, Psychology Now and numerous science bookazines. Ailsa's interest in the environment also lies outside of writing, as she has worked alongside Operation Wallacea (opens in new tab) conducting rainforest and ocean conservation research.