31 Euphrosyne
Encyclopedia
31 Euphrosyne is one of the largest main-belt asteroid
s, discovered by James Ferguson
on September 1, 1854. It was the first asteroid found from North America. It is named after Euphrosyne
, one of the Charites
in Greek mythology
.
It is a fairly dark body near the belt's outer edge. Consequently Euphrosyne is never visible with binoculars
, having a maximum magnitude at the best possible opposition of around +10.2, as in November 2011, which is actually fainter than any of the thirty asteroids previously discovered.
It is a very little-studied body despite being one of the largest asteroids. It is a C-type asteroid with a primitive surface. Its orbit, however, is quite unusual and bears a considerable resemblance to that of 2 Pallas
in its high inclination and eccentricity. Whereas Pallas and Eris
- the only larger bodies with comparably tilted orbits - have nodes near perihelion and aphelion, Euphrosyne's perihelion lies at the northernmost point of its orbit. During a rare perihelic opposition Euphrosyne is very high in the sky from northern latitudes, but invisible from such countries as New Zealand
and Chile
.
The mass estimate of Euphrosyne in Baer (2011) makes it apparently the 5th-most-massive asteroid, coming after only the big four. It also has the highest estimated density, indicating that it is a solid body like the other largest asteroids. However, all large asteroids with comparable densities (16 Psyche
and 532 Herculina
) have very large uncertainties, so both the mass and density are likely to be lower than the median estimate.
Its rotation period is typical for large asteroids. Nothing is known of its axial tilt
.
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, discovered by James Ferguson
James Ferguson (astronomer)
James Ferguson was an American astronomer and engineer born in Scotland who made the first discovery of an asteroid from North America . Starting in 1847, he worked at the U.S...
on September 1, 1854. It was the first asteroid found from North America. It is named after Euphrosyne
Euphrosyne (mythology)
In Greek mythology, Euphrosyne In Greek mythology, Euphrosyne In Greek mythology, Euphrosyne (Εὐφροσύνη; was one of the Charites, known in English also as the "Three Graces". Her best remembered representation in English is in Milton's poem of the active, joyful life, "L'Allegro". She is also the...
, one of the Charites
Charites
In Greek mythology, a Charis is one of several Charites , goddesses of charm, beauty, nature, human creativity and fertility. They ordinarily numbered three, from youngest to oldest: Aglaea , Euphrosyne , and Thalia . In Roman mythology they were known as the Gratiae, the "Graces"...
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...
.
It is a fairly dark body near the belt's outer edge. Consequently Euphrosyne is never visible with binoculars
Binoculars
Binoculars, field glasses or binocular telescopes are a pair of identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes when viewing distant objects...
, having a maximum magnitude at the best possible opposition of around +10.2, as in November 2011, which is actually fainter than any of the thirty asteroids previously discovered.
It is a very little-studied body despite being one of the largest asteroids. It is a C-type asteroid with a primitive surface. Its orbit, however, is quite unusual and bears a considerable resemblance to that of 2 Pallas
2 Pallas
Pallas, formally designated 2 Pallas, is the second asteroid to have been discovered , and one of the largest. It is estimated to constitute 7% of the mass of the asteroid belt, and its diameter of 530–565 km is comparable to, or slightly larger than, that of 4 Vesta. It is however 20%...
in its high inclination and eccentricity. Whereas Pallas and Eris
Eris (dwarf planet)
Eris, formal designation 136199 Eris, is the most massive known dwarf planet in the Solar System and the ninth most massive body known to orbit the Sun directly...
- the only larger bodies with comparably tilted orbits - have nodes near perihelion and aphelion, Euphrosyne's perihelion lies at the northernmost point of its orbit. During a rare perihelic opposition Euphrosyne is very high in the sky from northern latitudes, but invisible from such countries as New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
and Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
.
The mass estimate of Euphrosyne in Baer (2011) makes it apparently the 5th-most-massive asteroid, coming after only the big four. It also has the highest estimated density, indicating that it is a solid body like the other largest asteroids. However, all large asteroids with comparable densities (16 Psyche
16 Psyche
16 Psyche )is one of the ten most massive main-belt asteroids. It is over 200 kilometers in diameter and contains a little less than 1% of the mass of the entire asteroid belt. It is the most massive of the metallic M-type asteroids....
and 532 Herculina
532 Herculina
- Discovery :It was discovered on April 20, 1904, by Max Wolf in Heidelberg, and initially catalogued as 1904 NY. The origin of its name is not known; it may be named after the mythical Hercules, or after an unknown woman of that name...
) have very large uncertainties, so both the mass and density are likely to be lower than the median estimate.
Its rotation period is typical for large asteroids. Nothing is known of its 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...
.
External links
- Orbital simulation from JPL (Java) / Horizons Ephemeris