The formation of Mars happening further away from the Sun - where there is much less rock - meant it was destined to be a smaller planet and its core would cool quickly.

Best of Earth Science: http://bit.ly/EarthLabOriginals
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The Planets (2019)
This stunningly ambitious series brings to life the most memorable events in the history of the solar system, by using groundbreaking visual effects to tell the thrilling story of all eight planets. Transporting you to the surface of these dynamic worlds to witness the moments of high drama that shaped each one, The Planets reveals how the latest science allows us to unlock their past lives. It pieces together clues of magnificent lost waterfalls on Mars, the mass planetary migrations as they jostled for position early in their history, and even the distant fate of Saturn as one of its moons awakens to form a beautiful water world.

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