Humans have always lived on the Earth. In that time, they’ve discovered plenty of its wonders and secrets, though many more still wait to be revealed. From what’s already been discovered, here are essential Earth Facts to help you understand our planet better.
Earth formed during the Hadean Eon.
The Hadean Eon lasted for approximately 600 million years, for 4.6 billion to 4 billion years ago. Scientists think that the Earth formed from dust clumping together in a cloud of gas and dust around the young Sun. Earth at this time was a volcanic world, with many volcanoes erupting at the same time. Asteroid impacts were also very common at this time. The hellish conditions of the young Earth are why this period of time has the name Hadean Eon, from Hades, the Greek god of the underworld. Talk about a fiery beginning as far as Earth Facts are concerned.
Earth’s water came from various sources.
The biggest source was water vapor in the eruption clouds of early Earth’s volcanoes. Water vapor was also in the gases slowly pouring out of dormant volcanoes and other geological formations on early Earth. Comets impacting the planet added more water. As the planet cooled, water vapor turned liquid and rained down on the surface. Over hundreds of millions of years, the liquid water gathered and grew, forming pools, lakes, rivers, seas, and finally the oceans.
An impact with another planetary body formed the Moon around 4.5 billion years ago.
Scientists theorize that the Moon formed when a smaller body called Theia slammed into the Earth 4.5 billion years ago. This threw large amounts of debris into the surrounding space, while Theia’s core sank into and merged with Earth’s core. Over billions of years, the debris surrounding the Earth clumped together into a single body, orbiting the Earth. That orbiting body is what we know today as our Moon.
The first life on Earth also appeared during the Hadean Eon.
Scientists based this on microfossils dating back to around 4.3 billion years ago. These microfossils indicate the first life forms are similar to deep-sea bacteria that grow around hydrothermal vents. The surrounding water protected them from extreme temperatures and radiation if cutting them off from sunlight. Without sunlight for photosynthesis, these ancient life forms instead fed on the chemicals belched out by the hydrothermal vents. An adaptable example of Earth Facts, to be sure.
Life on Earth first appeared about 3.5 billion years ago.
Scientists determined this in 2017, following the discovery of bacterial microfossils in geyserite samples. Like their underwater cousins, these bacteria depended on chemicals from geologically-active water formations like geysers and hot springs to survive.
The magnetic field around Earth first appeared during the Archean Eon.
Interactions between Earth’s inner and outer cores generate a magnetic field around the planet. This magnetic field is what allows a compass to point which way is north or south. It also protects the planet from the Solar Wind, a stream of energy from the Sun that could blow our atmosphere away. The generation of the magnetic field began around 3.5 billion years ago, as the heavy elements of iron and nickel settled in the center of the Earth. At the time though, it was only half as strong as it is today but grew stronger over billions of years.
Earth’s magnetic field does not provide complete protection.
It may seem like it, but this isn’t one of the worrying Earth Facts. When the Sun is especially active, small amounts of high-energy particles slip through gaps in Earth’s magnetic field. These then strike against the ionosphere, the upper layer of Earth’s atmosphere. Interactions between those particles and our atmosphere generate energy bursts, appearing as lights in the sky. These usually appear in northern and southern latitudes, aurora borealis, the northern and southern lights.
The first photosynthetic life forms appeared 2.7 billion years ago.
Scientists think these life forms were single-cell bacteria in the early oceans. They used sunlight to help break down carbon dioxide into oxygen and to power other biochemical processes. Oxygen is a waste gas for photosynthetic life forms, and it’s released into the surroundings. At the time, free oxygen on the early Earth was rare, but as photosynthesis grew more common, free oxygen rose over time.
The Oxygen Crisis took place over 2 billion years ago.
Today we’re so used to breathing oxygen and knowing it as essential for life, that we forget its other properties. Oxygen is a very active element and reacts easily with other elements. In fact, it’s from oxygen that the term oxidation comes from. Billions of years ago, rising oxygen levels produced by photosynthesis proved devastating to early life forms. Scientists estimate that this period lasted over 400 million years, from 2.4 to 2 billion years ago.
Since they evolved from an oxygen-poor environment, the rising oxygen levels either suffocated or destroyed them outright. Those that survived evolved complex cellular repair mechanisms to handle oxygen’s reactive properties. Scientists theorize that this opened the door for the evolution of multicellular life. There’s an interesting example of Earth facts.
The Cambrian Explosion happened 541 million years ago.
The Cambrian Explosion is one of the most important events in the history of life on Earth. Before the explosion, the most complex life on Earth was sheet-like colonies of single-celled life. During the explosion, multicellular life flourished, with all plant and animal phyla evolving at this time. The reason for this explosion of life is still under study at this time.
Five mass extinctions have taken place in Earth’s history.
The first of those was the Ordovician-Silurian Extinction Event, between 450 and 440 million years ago. It was also the second-largest of the five, killing between 60 to 70% of all life on Earth. The Late Devonian Extinction Event followed, between 375 to 360 million years ago.
The Permian Extinction Event followed 252 million years ago, with the Triassic Extinction Event 201 million years ago. The last of the five mass extinctions is the Cretaceous Extinction Event, taking place 66 million years ago. Definitely one of the grim Earth facts.