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Unknown Earth: Our planet's seven biggest mysteries - Dr Stuart Clark

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New Scientist issue 2675
I have contributed to a special feature in New Scientist


“It's the place we call home, but there is much about planet Earth that remains frustratingly unknown. How did it form from a cloud of dust? How did it manage to nurture life? And just what is going on deep within its core? New Scientist investigates these and other fundamental questions about our beautiful, enigmatic world.”

 

 

I tackled the first three of the seven biggest mysteries:


How come Earth got all the good stuff?
“Look around our solar system and you could be forgiven for thinking its eight planets drifted in from completely different parts of the cosmos. Yet they all formed from the same cloud of gas and dust that surrounded the sun more than 4.5 billion years ago. As gravity pulled this cloud together with the sun at its centre, dust grains collided and stuck to each other, growing in size and generating ever-larger gravitational fields. These clumps collided and merged, building the planets we know today.
That's the big picture, but the details of what happened in the early stages of Earth's life remain a mystery. Solving it is fundamental to understanding why Earth is so suitable for life. We know that its distance from the sun provides the right ...”

The complete article is 631 words long.  You can read it here but a subscription is required.

 

What happened during Earth's dark ages?
“Some 4.53 billion years ago, as the infant Earth was settling down in its orbit around the sun, disaster struck. Our young planet was dealt a glancing blow by an object the size of Mars. Debris from the impact was thrown into Earth's orbit to form the moon, and the energy of the collision supplied enough heat to melt the Earth's upper layers, erasing our planet's previous geological record. This has left a yawning chasm in our knowledge of the planet's first 500 million years, a period that has become known as the Hadean era, Earth's darkest age. We know almost nothing about it.
"Time zero" for the solar system is generally agreed to be 4.567 billion years ago, and by 4.55 billion years ago, about 65 per cent of ... “

The complete article is 618 words long.  You can read it here but a subscription is required.

 

Where did life come from?
“Leaving aside the remote possibility that life arrived on Earth on a meteorite from somewhere else, we have to assume that it emerged from whatever physical and chemical conditions existed in the planet's youth. Working out what these conditions were is problematical, mainly because the Earth we live on today retains almost no trace from that time.
To date, the earliest evidence for life comes from sedimentary rocks that are 3.8 billion years old. Discovered in the 1990s in west Greenland, these rocks have an unusually low proportion of the heavy isotope of carbon. This is thought to be a sign of microorganisms at work, because the lighter isotope passes more easily through cell walls and so accumulates wherever microbes have been. …”

The complete article is 536 words long.  You can read it here but a subscription is required.

 

You can read all the mysteries here but again, a subscription is required.

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