52 Europa
52 Europa is one of the larger asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

s in the asteroid belt
Asteroid belt
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...

, having a diameter of 300 km. It was discovered on February 4, 1858, by Hermann Goldschmidt from his balcony in Paris
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...

. It is named after Europa
Europa (mythology)
In Greek mythology Europa was a Phoenician woman of high lineage, from whom the name of the continent Europe has ultimately been taken. The name Europa occurs in Hesiod's long list of daughters of primordial Oceanus and Tethys...

, one of Zeus
In the ancient Greek religion, Zeus was the "Father of Gods and men" who ruled the Olympians of Mount Olympus as a father ruled the family. He was the god of sky and thunder in Greek mythology. His Roman counterpart is Jupiter and his Etruscan counterpart is Tinia.Zeus was the child of Cronus...

's conquests in Greek mythology
Greek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...

, a name it shares with Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

's moon Europa
Europa (moon)
Europa Slightly smaller than Earth's Moon, Europa is primarily made of silicate rock and probably has an iron core. It has a tenuous atmosphere composed primarily of oxygen. Its surface is composed of ice and is one of the smoothest in the Solar System. This surface is striated by cracks and...


Physical characteristics

Europa is approximately the seventh largest asteroid by volume. However, it has a low density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...

 (i.e. is highly porous), presumably through having suffered a particularly severe collision. In 2001, Michalak estimated Europa to have a mass of (5.2±1.8) kg. In 2007, James Baer and Steven R. Chesley estimated Europa to have a mass of (1.9±0.4) kg. A more recent estimate by Baer suggests it has a mass of 1.65 kg.

Europa is a very dark carbonaceous C-type
C-type asteroid
C-type asteroids are carbonaceous asteroids. They are the most common variety, forming around 75% of known asteroids, and an even higher percentage in the outer part of the asteroid belt beyond 2.7 AU, which is dominated by this asteroid type...

, and is the fourth largest of this group. Spectroscopic studies have found evidence of olivine
The mineral olivine is a magnesium iron silicate with the formula 2SiO4. It is a common mineral in the Earth's subsurface but weathers quickly on the surface....

s and pyroxene
The pyroxenes are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. They share a common structure consisting of single chains of silica tetrahedra and they crystallize in the monoclinic and orthorhombic systems...

s on the surface,[5] and there is some indication that there may be compositional differences between different regionshttp://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1991PhDT.......105S&db_key=AST&data_type=HTML&format=&high=444b66a47d24766 It orbits close to the Hygiea asteroid family
Hygiea family
The Hygiea family of asteroids is a grouping of dark, carbonaceous C-type and B-type asteroids in outer main belt, the largest member of which is 10 Hygiea. About 1% of all known main belt asteroids belong to this family.-Characteristics:...

, but is not a member.

Lightcurve data for Europa has been particularly tricky to interpret, so much so that for a long time its period of rotation was in dispute (ranging from 5 and a half hours to 11 hours), despite numerous observations.[8] It has now been determined that Europa is a prograde
Prograde can refer to:*Prograde or direct motion, in astronomy, a type of motion of astronomical bodies* Prograde metamorphism, in geology, describes mineral changes in rocks under increasing pressure and/or temperature conditions...

 rotator, but the exact direction in which its pole points remains ambiguous. The most detailed analysis indicates that it points either towards about ecliptic coordinates
Ecliptic coordinate system
The ecliptic coordinate system is a celestial coordinate system that uses the ecliptic for its fundamental plane. The ecliptic is the path that the sun appears to follow across the celestial sphere over the course of a year. It is also the intersection of the Earth's orbital plane and the celestial...

 (β, λ) = (70°, 55°) or (40°, 255°) with a 10° uncertainty.[2]. This gives an axial tilt
Axial tilt
In astronomy, axial tilt is the angle between an object's rotational axis, and a line perpendicular to its orbital plane...

 of about 14° or 54°, respectively.


It has been found that the reputed cataclysmic variable star CV Aquarii, discovered in 1934, was actually a misidentification of 52 Europa.http://www.aavso.org/publications/ejaavso/v28n2/103.pdf

External links

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