Eventually they will collide, and the larger planet always wins. “About 4.5 billion years ago, when the solar system was about 50 million years old, the black proto-Earth and a slightly smaller planet-size competitor were jockeying for the same narrow band of solar system real estate…A rule of astrophysics is that no two planets can share the same orbit. Hazen, a professor of Earth Science, writes of the impact quite clearly: In his book The Story of Earth: The First 4.5 Billion Years from Stardust to Living Planet (Penguin, 2013) Robert M. In Greek mythology Theia is the mother of Helios (the sun) and Selene (the moon). Theia is the name given to that object because of our moon. Why so?Įarly on (approximately 4.5 billion years ago) Earth was involved in a massive collision with an Earth trojan, a planetary-mass object that orbits the sun in the vicinity of Earth’s own orbit. It tilts 23.5º from the plane of the ecliptic, the invisible 90-degree vertical axis that runs between the poles. So much for pride and vanity.īut it’s life that matters, not vanity, even a life led off kilter. If the bright lights of Broadway form the downtown centre of our galactic home, we are hicks living out in the sticks. We inhabit a planet in the Orion arm of our galaxy, 26,000 light years from the centre. The solar system was born roughly 4.6 billion years ago following the gravitational collapse of a small part of a giant interstellar molecular cloud, a part that eventually became the Milky Way. We have gravity to thank for our existence. To learn more about how and for what purposes Amazon uses personal information (such as Amazon Store order history), please visit our Privacy Notice. You can change your choices at any time by visiting Cookie Preferences, as described in the Cookie Notice. Click ‘Customise Cookies’ to decline these cookies, make more detailed choices, or learn more. Third parties use cookies for their purposes of displaying and measuring personalised ads, generating audience insights, and developing and improving products. This includes using first- and third-party cookies, which store or access standard device information such as a unique identifier.

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