Bright Side shares 13 facts with you about our world that we don’t have any explanation for.
13. We’ve never reached the mantle
Seismologists believe that the inner core of our planet is solid, while the outer one is liquid and molten. Next comes the mantle, with the crust floating on top. However, we still have no idea what it consists of, because we’ve never reached it: its depth is from 30 km to 2,900 km, and the deepest well mankind has dug so far is the Kola borehole in Russia, which is just 12.3 km deep.
12. The poles can change
Earth’s magnetic poles can move and even change direction altogether, and scientists have found that it’s happened many times. The latest switch happened 10 million years ago and will probably occur again, but no one knows why.
11. We used to have two moons
Astronomers say Earth had two satellites about 4.6 million years ago. The second one was about 1,200 km across and went around the same orbit the Moon does, until they collided. Such a cataclysm may explain why the two sides of the Moon are so different.
Few people are aware that there earthquakes also occur on the Moon. Unlike terrestrial ones, though, they’re not quite as powerful, and occur very rarely. There’s a theory that they happen because of the tidal forces of the Sun and Earth, as well as falling meteorites.
9. Earth spins really fast
Earth is spinning at 1,600 km/h, and its movement around the Sun is even faster at 108,000 km/h. We, though, can only feel the movement when its speed changes. Because of the constant speed and the force of gravity, we don’t feel it at all.
8. Time is “growing”
620M years ago, a day on Earth lasted 21.9 hours. Earth is gradually slowing down, but it happens at a rate of about 70 msec per 100 years, so it would take 100M years for a day to last 24 hours.
7. Strange gravity
Our planet isn’t a perfect sphere, so there are high- and low-gravity areas on it. One such anomaly is Hudson Bay in Canada. Scientists found out that weak gravity there is due to the low density caused by rapidly melting glaciers.
6. The hottest and coldest points on Earth
The hottest place on the planet is in Aziziya, Libya, where temperatures of up to +58°С occur. The coldest place is the Antarctic, where it goes down to −73°С. But the lowest observed temperature was registered at the Russian Vostok Station on July 21, 1983 (-89.2°С).
5. The planet is severely polluted
This is not really news. However, astronauts say that in 1978, the view of Earth was rather different from what we see now. With lots of space debris and waste, our blue, green and white planet is becoming brown, gray and black.
4. Earth consists of iron, oxygen, and silicon
If we separated out the constituent elements of our planet, it would look like this: 32.1% iron, 30.1% oxygen, 15.1% silicon, and 13.9% magnesium. Most of the iron (about 90%) is considered to be contained in the core, while the crust contains the most oxygen (47%).
3. The Earth used to be purple
Ancient plants used retinal instead of chlorophyll to absorb light, which made them reflect back red and blue, not green, giving purple as a result. Incidentally, certain bacteria still use retinal.
2. A hidden ocean
Scientists found a huge pool of water deep below Earth’s surface at 410-660 km. It’s 2.7 billion years old, and has been found thanks to ringwoodite contained in the mantle. The water is under immense pressure, and its volume is enough to fill all the Earth’s oceans three times over. This has given birth to a theory that the oceans appeared because of an underground oceanic explosion.
1. Life on Mars
After years of speculation about lifeforms on other planets, scientists have found some encouraging signs that a vital molecule required for this is present on Mars, as seen in formations in the Gale crater. Also, some large carbon-based molecules remain in the soil of Mars, and they aren’t just the result of contamination from the rover itself. It would suggest, that Mars had life on it long before Earth did.