4769 Castalia (; ''
prov. designation:'' ) is a
near-Earth object
A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun ( perihelion) is less than 1.3 times the Earth–Sun distance (astronomical unit, AU). This definition applies to the object's orbit a ...
and
potentially hazardous asteroid of the
Apollo group, approximately in diameter and was the first
asteroid
An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...
to be modeled by
radar imaging
Radar is a system that uses radio waves to determine the distance (''ranging''), direction (geometry), direction (azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to det ...
. It was discovered on 9 August 1989, by American astronomer
Eleanor Helin
Eleanor Francis "Glo" Helin (née Francis, 19 November 1932 – 25 January 2009) was an American astronomer. She was principal investigator of the Near-Earth Asteroid Tracking (NEAT) program of NASA's Jet Propulsion Laboratory. (Some sources gi ...
(
Caltech
The California Institute of Technology (branded as Caltech) is a private university, private research university in Pasadena, California, United States. The university is responsible for many modern scientific advancements and is among a small g ...
) on photographic plates taken at
Palomar Observatory
The Palomar Observatory is an astronomical research observatory in the Palomar Mountains of San Diego County, California, United States. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...
in California. It is named after
Castalia, a
nymph
A nymph (; ; sometimes spelled nymphe) is a minor female nature deity in ancient Greek folklore. Distinct from other Greek goddesses, nymphs are generally regarded as personifications of nature; they are typically tied to a specific place, land ...
in
Greek mythology
Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories conc ...
. It is also a
Mars- and
Venus-crosser asteroid.
General information
On 25 August 1989 Castalia passed
[ (within eleven ]lunar distance
The instantaneous Earth–Moon distance, or distance to the Moon, is the distance from the center of Earth to the center of the Moon. In contrast, the Lunar distance (LD or \Delta_), or Earth–Moon characteristic distance, is a unit of measure ...
s) of Earth, allowing it to be observed with radar
Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...
from the 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 F ...
by Scott Hudson (Washington State University
Washington State University (WSU, or colloquially Wazzu) is a Public university, public Land-grant university, land-grant research university in Pullman, Washington, United States. Founded in 1890, WSU is also one of the oldest Land-grant uni ...
) and Steven J. Ostro ( JPL). The data allowed Hudson et al. to produce a three-dimensional model
A model is an informative representation of an object, person, or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin , .
Models can be divided in ...
of the object. During the 1989 passage Castalia peaked at an apparent magnitude
Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...
of 12.minimum orbit intersection distance
Minimum orbit intersection distance (MOID) is a measure used in astronomy to assess potential close approaches and collision risks between astronomical objects. It is defined as the distance between the closest points of the osculating orbits o ...
(MOID) is less than 0.05 AU and its diameter is greater than 150 meters. The Earth-MOID is .[ Its orbit is well-determined for the next several hundred years.
]
See also
* List of notable asteroids
References
External links
*
NASA Asteroid Radar Search – The 228 Radar-Detected Asteroids: Asteroid 4769 Castalia
*
*
*
{{DEFAULTSORT:Castalia
004769
Discoveries by Eleanor F. Helin
Named minor planets
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