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In 1862, the physicist William Thomson, 1st Baron Kelvin published calculations that fixed the age of Earth at between 20 million and 400 million years. [19] [20] He assumed that Earth had formed as a completely molten object, and determined the amount of time it would take for the near-surface temperature gradient to decrease to its present value.
Flag of Earth proposed by James W. Cadle in 1970. In May 1970, James W. Cadle, a farmer from Homer, Illinois, proposed his version of the flag of Earth, that consisted of a blue circle representing the Earth, placed in the centre of the flag, in front of a segment of a larger yellow circle, representing the Sun, placed on the left side of the map, and a smaller white circle, representing the ...
In 2008, Google developed a partnership with GeoEye to launch a satellite providing Google with high-resolution (0.41 m monochrome, 1.65 m color) imagery for Google Earth. The satellite was launched from Vandenberg Air Force Base on September 6, 2008. [116] Google also announced in 2008 that it was hosting an archive of Life Magazine ' s ...
The geographical centre of Earth is the geometric centre of all land surfaces on Earth.Geometrically defined it is the centroid of all land surfaces within the two dimensions of the Geoid surface which approximates the Earth's outer shape.
The Hollow Earth is a concept proposing that the planet Earth is entirely hollow or contains a substantial interior space. Notably suggested by Edmond Halley in the late 17th century, the notion was disproven, first tentatively by Pierre Bouguer in 1740, then definitively by Charles Hutton in his Schiehallion experiment around 1774.
The first eon in Earth's history, the Hadean, begins with the Earth's formation and is followed by the Archean eon at 3.8 Ga. [2]: 145 The oldest rocks found on Earth date to about 4.0 Ga, and the oldest detrital zircon crystals in rocks to about 4.4 Ga, [34] [35] [36] soon after the formation of the Earth's crust and the Earth itself.
Another early Google Earth Outreach project was with Appalachian Voices, which used the tools to illustrate the effects of mountaintop removal mining, with before and after pictures of 470 mountains that have been razed for coal. Within a week of the launch of their project using Google Earth in 2007, their online petition got 12,000 signatures.
Earth's gravity measured by NASA GRACE mission, showing deviations from the theoretical gravity of an idealized, smooth Earth, the so-called Earth ellipsoid.Red shows the areas where gravity is stronger than the smooth, standard value, and blue reveals areas where gravity is weaker (Animated version).