What Is the Earth?

What Is the Earth?

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.

- Carl Sagan, Pale Blue Dot, 1994

Podcast of the Day

Melvyn Bragg discusses the origin of the Earth. Ideas used to be very clear about its origins. Bishop Ussher, in 1654 arrived at an exact figure and specified it in his work Annalis Veteris et Novi Testamenti: He deduced that work on Planet Earth began at exactly 9am, on Monday 23rd October 4004 BC. The date was then printed in the margin of The Bible and preached from the pulpit, and right up to the nineteenth century to the left of ‘In The Beginning…’ was specified ‘Before Christ 4004’.Christian believers thought the creation story was solid as a rock…until the geologists arrived. First Hutton, then Smith, and then Lyell smashing away at orthodox belief in a way that made poor Ruskin quail, but in doing so they created a science.

Listen to the In Our Time episode on The Earth's Origin

Video of the Day

Short Article of the Day

It all started with a tremendous bang. Somewhere in our galaxy a star exploded, throwing out masses of gas and dust. This supernova, as these explosions are called, happened about 5bn years ago. The wreckage from the explosion then crashed into a nearby cloud of gas, bringing together the ingredients for our solar system to form.

Because the explosion was so energetic it made the dust mixture very hot and things began to cook. Little bits of dust began to cluster, making bigger and bigger lumps, and the mixture began to pull together under its own gravity.

Eventually the central lump became so hot and dense that it started to generate its own energy, igniting nuclear fires. This was the birth of our sun...

Continue reading Kate Ravilious' article: How did our planet form?

Further Reading

Earth is the third planet from the Sun and the only object in the Universe known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.

Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on the Earth. The gravitational interaction between the Earth and Moon causes ocean tides, stabilizes the Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets...

Continue reading the Wikipedia article on the Earth

Bonus Webcomic

Geography - xkcd

Related Topics

If you’re interested in the Earth, check out some of the following related topics for more resources:

Archaeology | Climate ChangeHuman Evolution | Nature

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