{"id":48719,"date":"2023-08-24T13:00:29","date_gmt":"2023-08-24T13:00:29","guid":{"rendered":"http:\/\/5b31543f-5a3d-420d-8aa0-a9e94d1c47f1"},"modified":"2023-08-24T13:32:35","modified_gmt":"2023-08-24T13:32:35","slug":"how-old-is-the-earth","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/how-old-is-the-earth\/","title":{"rendered":"How old is the Earth?<\/strong>"},"content":{"rendered":"
A guide to the history of our planet’s formation around the Sun, and just how old current estimates believe Earth to be. <\/p>
By Russell Deeks\n <\/p>
Published: Thursday, 24 August 2023 at 13:00 PM<\/p>
\n\n
How old is the Earth?<\/strong><\/h1>
According to most estimates, planet Earth is roughly 4.55 billion years old.<\/p>
While that’s not as old as the Sun itself (for reasons that should be self-explanatory!), our home planet Earth is clearly very old.<\/p>
On order to understand just why Earth is so old, we need to look way way back, to the formation of the Solar System, and current theories as to how planets form.<\/p>
A primer on planer formation<\/strong><\/h2>\n
An image of a protoplanetary disc around star HL Tauri. The dark rings could indicate newly-forming planets in orbit, pushing aside dust as they go. Credit: ALMA (ESO\/NAOJ\/NRAO)<\/figcaption><\/figure>\n
Planets form when gravity causes particles orbiting a star \u2013 in our case, the Sun \u2013 to clump together in ever-larger bodies, a process known as accretion.<\/p>
This is why the disk of cosmic material surrounding a newborn star is known as an accretion disk<\/a>, or a protoplanetary disk.<\/p>
Put very simply, dust particles collide and fuse to form tiny pebbles, pebbles collide and fuse to form larger rocks, rocks collide and fuse to form larger bodies called \u2018planetesimals\u2019, and so it goes on.<\/p>
In the case of Earth, this process would have begun shortly after the Sun itself started to take shape, around 4.6 billion years ago.<\/p>
We know this through the study of rocks.<\/p>
How rocks reveal Earth’s age<\/strong><\/h2>\n $\"An$
An outcrop of metamorphosed rock from Nuvvuagittuq. Credit: NASA<\/figcaption><\/figure>\n
The oldest rocks on Earth\u2019s surface can be found in Quebec: forming a rocky outcrop known as the Nuvvuagittuq Greenstone Belt, they are around 4.3 billion years old.<\/p>
But geologists know from analysing lead isotopes found in meteorites that the Solar System itself is 4.6 billion years old.<\/p>
And that Earth\u2019s mantle is formed from much the same material as those meteorites.<\/p>
What was early Earth like?<\/strong><\/h2>\n $\"A$
A molten exoplanet. Credit: Mark Garlick \/ Science Photo Library<\/figcaption><\/figure>\n
Early Earth was a barren, rocky and extremely hot planet whose only atmosphere consisted of gases pumped out by the many volcanoes on its surface.<\/p>
It was regularly bombarded by meteors, too.<\/p>
It wouldn\u2019t be too long before a collision with another large body that scientists dubbed Theia knocked a huge chunk out of it, forming the Moon<\/a>.<\/p>
Not a good place for a holiday, then.<\/p>
But within half a billion years or so, Earth began to cool.<\/p>
The volatile, volcanic surface became more stable and able to support oceans of liquid water.<\/p>
And incredibly, as early as four billion years ago, the first, single-celled forms of life began to appear. <\/p>
How all that happened, though, is a question for another day\u2026<\/p> <\/body><\/html>\n
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