How Much Do You Know About the Planet Earth?

Zoe Samuel

Image: shutterstock

About This Quiz

The Earth is home to all of us, but we probably know more about our literal homes than about our planetary one. People used to believe all sorts of wrong facts about the Earth: that it was flat, that it was the center of the universe, that it was 6,000 years old. We know now that humanity's residence represents a small part of Earth's history, and that even we don't know everything about this great big ball of rock. Indeed, we know more about what's in space than about some of the less accessible places on Earth, like the depths of the ocean and certain borderline, unreachable caves and wildernesses.

This quiz will test your knowledge of this blue planet of ours. If you think you know the basics - where Earth is in the order of planets from the sun, how big it is, how many continents there are - you'll surely begin strong.  However, only an expert will make it through the tougher questions, as we get into population growth, sea level changes, and when the last Ice Age ended. 

Time to dredge up your history, geography, and economic knowledge, and get ready to impress even yourself!

To the nearest thousand, what is the circumference of the Earth?

The Earth is 25,000 miles around at the equator.

How old is the Earth?

The Earth is probably 4.5 billion years old, but the universe is more like 13.8 billion years old. The Earth came together out of heavier metals that orbited the sun and cooled into our rocky planet.

What shape is the Earth?

The Earth is not actually perfectly spherical. It is mostly round, but slightly flatter at the top and bottom than around the equator, making it technically an oblate spheroid.

How much of the Earth is covered by water?

The Earth is 71 percent water. As sea levels rise, this number will go up a little.

In the order of planets from the sun, where is Earth?

Here's a good mnemonic for remembering the order of the planets from the sun: My Very Efficient Memory Just Summed Up Nine. Of course, if you see Pluto as a planet, you turn this into "My Very Efficient Memory Just Summed Up Nine Planets."

How far from the sun is the Earth?

The Earth is 93 million miles from the sun, on average. Since its orbit is not perfectly round, this distance changes.

How many moons does the Earth have?

The Earth definitely has one big visible moon that you can see from the planet's surface, but it is believed that there are many more moons, possibly thousands, which may be mostly very small and not visible.

How far is the moon from the earth?

The moon is in an elliptical orbit, so the distance changes, but it is generally around 240,000 miles away from the earth.

What is the Earth's core made of?

The earth's inner core is solid and mostly iron; the outer is an iron and nickel mix that is mostly liquid. The core is about 2,150 miles thick.

What shape did Christopher Columbus think the Earth was?

Contrary to popular belief, most people did not think the Earth was flat by the time Columbus set off. He thought it was probably pear-shaped and was keen to find out its circumference.

Who first figured out that the Earth is round?

Pythagoras first proposed the idea of a round planet. That didn't stop Galileo from being in serious trouble 2,000 years later for saying it.

What is the lowest place on Earth that isn't covered by water?

The Dead Sea is the lowest place on Earth. It is slowly evaporating, meaning its already high salt content is getting even higher.

What is the Ring of Fire?

The Ring of Fire is an area around the Pacific Ocean where tectonic plates meet, prompting many earthquakes and volcanoes.

What is the aurora borealis?

The aurora borealis is also known as the Northern Lights. It is caused by electrically-charged particles from the sun as they interact with the atmosphere.

How much of the Earth's land area is covered by forests?

Forests still cover about 1/3 of the Earth's land surface, accounting for 50 percent of the planet's plant activity.

What temperature would the Earth be if there were zero greenhouse gases in the atmosphere?

Greenhouse gases have raised the temperature of the planet from about zero degrees Fahrenheit to 59 degrees Fahrenheit, on average. Greenhouse gases have gone up as much as 30 percent, and there is a a lot of potential for this number to rise.

What is the highest possible sea level above current levels, if all the ice on the planet melted?

If all the ice on Earth were to melt, sea levels would rise about 220 feet. Most major coastal cities would be inundated, including entire countries, such as Bangladesh.

How thick is the atmosphere?

The atmosphere is 300 miles thick, but only the first few miles are breathable.

What is the driest place on Earth, besides the poles?

The driest place is the Atacama Desert which is on a high plateau in South America. Technically, Antarctica is drier, but it has a whole lot of ice.

What is the coldest inhabited place on Earth?

Oymyakon, Russia, is the coldest town on Earth that is continuously inhabited. It is a two-day drive from Yakutsk, and between October and March, it never gets above freezing.

How long does the Antarctic night last at the South Pole?

The polar night lasts 179 days. The area that doesn't see the sun for at least as long a period of time is bigger than just the pole, though, extending up into the 77th parallel and beyond.

How fast is the Earth spinning?

The Earth spins about 1,000 mph at the surface. Technically, however, if you are on the equator, you are going a little bit faster than someone who is in the Arctic circle.

What percentage of the atmosphere is oxygen?

About 21 percent of the atmosphere is oxygen. It is declining slightly which may be because air does escape a little into space, or because we're cutting down too many plants, which make oxygen. Most likely it is due to ocean acidification which harms ​phytoplankton that make most of our oxygen supply. If levels go below 18 percent, large mammals will not be able to live. Fortunately, we are a long way from that point.

How old is the oldest life form on Earth?

There are microfossils that suggest life has been around nearly as long as the planet. Some people believe that life on our planet was seeded by a comet.

How fast is the Earth going around the sun?

The Earth is going around the sun at 67,000 mph. Its orbit is defined by the fact that it goes exactly fast enough to not quite escape the sun's gravity.

What shape is the Earth's orbit?

The orbit of the Earth is indeed elliptical, which is like a long squashed oval. It means there are times we are closer to the sun and times we are further away.

Which of these is not one of the three kinds of rock on the Earth: sedimentary, fossilized, metamorphic, igneous?

Rocks can be sedimentary (laid down in layers), igneous (volcanic, i.e. formed by melting and reforming), or metamorphic (formed from the movement of Earth's crust but without melting). A life form can be fossilized, but a rock can't.

What is an earthquake?

An earthquake is what happens when two tectonic plates meet, separate, or go one over the other (known as subduction). The pressure of the two masses builds and builds, forming mountains or gorges when it happens slowly. When the pressure is too much, the plates suddenly slip, causing an earthquake.

What is a batholith?

A batholith is what you get when a crust of magma cools fast enough to form a specific shape. Sometimes the batholith is harder than other rocks around it, so it remains intact while the other rocks are slowly eroded.

What is the longest mountain ridge on the planet?

The Mid-Atlantic Ridge is the longest mountain range, since the sea floor is no flatter than the land! It has many islands along its 10,000 mile length where the mountains poke out.

What are the largest living structures on the planet?

Honey fungus have been measured at 2.4 miles long. They look like lots of little mushrooms, but are really one enormous organism.

What is the tallest manmade structure on Earth?

The Burj Khalifa was going to be called the Burj Dubai, but Dubai's economic crisis hit during construction and the structure had to be named after the guy who bailed out the project. It won't be the tallest building much longer, though.

What is the oldest continuously inhabited settlement on earth?

Damascus in Syria has been inhabited for 11,000 years, which means it predates our full move to a settled society. It has been through a lot of strife in that time and is currently mired in a very big and intractable war.

How do plants make oxygen?

Photosynthesis is the way that plants make oxygen, by using the energy from the sun to transform carbon dioxide. They "breathe" in the CO2 and "breathe" out the O2.

Which of these is NOT one of the three domains of life: Archaea, Bacteria, Fungi, and Eukarya?

The three domains are Archaea, Bacteria, and Eukarya.

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