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4769 Castalia
4769 Castalia (; ''Minor planet provisional designation, prov. designation:'' ) is a near-Earth object and potentially hazardous asteroid of the Apollo asteroid, Apollo group, approximately in diameter and was the first asteroid to be modeled by radar imaging. It was discovered on 9 August 1989, by American astronomer Eleanor Helin (Caltech) on photographic plates taken at Palomar Observatory in California. It is named after Castalia, a nymph in Greek mythology. It is also a Mars-crosser asteroid, Mars- and Venus-crosser asteroid. General information On 25 August 1989 Castalia passed (within eleven Lunar distance (astronomy), lunar distances) of Earth, allowing it to be observed with Radar astronomy, radar from the Arecibo Observatory by Scott Hudson (electrical engineer), Scott Hudson (Washington State University) and Steven J. Ostro (Jet Propulsion Laboratory, JPL). The data allowed Hudson et al. to produce a three-dimensional Mathematical model, model of the object. During ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arecibo Observatory
The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC) and formerly known as the Arecibo Ionosphere Observatory, is an observatory in Barrio Esperanza, Arecibo, Puerto Rico owned by the US National Science Foundation (NSF). The observatory's main instrument was the Arecibo Telescope, a spherical reflector dish built into a natural sinkhole, with a cable-mount steerable receiver and several radar transmitters for emitting signals mounted above the dish. Completed in 1963, it was the world's largest single-aperture telescope for 53 years, surpassed in July 2016 by the Five-hundred-meter Aperture Spherical Telescope (FAST) in China. On August 10 and November 6, 2020, two of the receiver's support cables broke and the NSF announced that it would decommission the telescope. The telescope collapsed on December 1, 2020. In 2022, the NSF announced the telescope will not be rebuilt, with an educational facility to be established on the site. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |