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Charlotte Amelines, MSN Environment Contributor

Earth’s seven biggest mysteries

Environmental campaigns you should get involved in today (Image © Czarek Sokolowski/AP/PA Photos)

Planet Earth – it’s the only place we have and ever will live. But when asked fundamental questions about its nature, we’re often stumped.

How did such a rich and fertile world form from a lifeless cloud of dust and gas? What happened in between its creation and the appearance of life? How indeed, did life begin, how much is there and why has it ended abruptly in mass extinctions more than once?

The truth is that these and many more key questions still baffle our most brilliant scientists, and our ever-changing world yields its secrets with extraordinary reluctance. But piece-by-piece, we are putting together the puzzle that is the planet Earth.

Follow us on a tour of our planet’s seven deepest mysteries, and how scientists hope one day to solve them.

Why is Earth so uniquely well suited to life?
What happened in Earth’s infancy?
How and where did life begin?
What drives evolution?
What goes on in the Earth’s core?
What causes mass extinctions?
How many species exist on Earth?
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