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Knowledge of the location of Earth has been shaped by 400 years of telescopic observations, and has expanded radically since the start of the 20th century. Initially, Earth was believed to be the center of the Universe, which consisted only of those planets visible with the naked eye and an outlying sphere of fixed stars. [1]
99942 Apophis (provisional designation 2004 MN 4) is a near-Earth asteroid and a potentially hazardous object with a diameter of 370 metres (1,210 feet) [3] that caused a brief period of concern in December 2004 when initial observations indicated a probability up to 2.7% that it would hit Earth on April 13, 2029.
Pale Blue Dot is a photograph of Earth taken on February 14, 1990, by the Voyager 1 space probe from an unprecedented distance of approximately 6 billion kilometers (3.7 billion miles, 40.5 AU), as part of that day's Family Portrait series of images of the Solar System.
Creola Katherine Johnson (née Coleman; August 26, 1918 – February 24, 2020) was an American mathematician whose calculations of orbital mechanics as a NASA employee were critical to the success of the first and subsequent U.S. crewed spaceflights.
Double Asteroid Redirection Test (DART) was a NASA space mission aimed at testing a method of planetary defense against near-Earth objects (NEOs). [4] [5] It was designed to assess how much a spacecraft impact deflects an asteroid through its transfer of momentum when hitting the asteroid head-on. [6]
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 ...
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).
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.