1036 Ganymed
Encyclopedia
1036 Ganymed is the largest Amor asteroid
, at about 32 km in diameter. It was discovered by Walter Baade
on October 23, 1924, and is named after Ganymede
, the Trojan prince turned god whom Zeus
designated the cupbearer to the Greek gods (Jupiter's moon Ganymede
is also named after that individual). It has a very well determined orbit, and its next pass of the Earth will be at a distance of 0.359104 AU on 2011-Oct-13. It is also a Mars-crosser asteroid
, and will pass 0.02868 AU from Mars on 2176-Dec-16.
, meaning that it is relatively reflective and composed of iron
- and magnesium
-silicates. Spectral measurements put Ganymed in the S (VI) spectral subtype, indicating a surface rich in orthopyroxenes, and possibly metals (although if metals are present they are covered and not readily apparent in the spectra).
In 1998, radar observations of Ganymed by the Arecibo radio telescope produced images of the asteroid, revealing a roughly spherical object. Also around this time a study of several asteroids' visual lightcurve and polarization curves was conducted (the data for Ganymed is limited due to poor weather at the time). The study concluded that there was a weak correlation between the lightcurve and polarimetry curve as a function of rotation angle. Because polarization is dependant on surface terrain and composition, rather than the observed size of the object like the lightcurve, this suggests that the surface features of the asteroid are roughly uniform over its observed surface.
More recent observations of Ganymed's lightcurve, reported in 2007, confirm a rotation period of 10.314 ± 0.004 h
and a lightcurve amplitude of 0.12 mag
.
One occultation
of a star
by Ganymed was observed from California
on August 22, 1985.
Amor asteroid
The Amor asteroids are a group of near-Earth asteroids named after the asteroid 1221 Amor. They approach the orbit of the Earth from beyond, but do not cross it. Most Amors do cross the orbit of Mars...
, at about 32 km in diameter. It was discovered by Walter Baade
Walter Baade
Wilhelm Heinrich Walter Baade was a German astronomer who worked in the USA from 1931 to 1959.-Biography:He took advantage of wartime blackout conditions during World War II, which reduced light pollution at Mount Wilson Observatory, to resolve stars in the center of the Andromeda galaxy for the...
on October 23, 1924, and is named after Ganymede
Ganymede (mythology)
In Greek mythology, Ganymede is a divine hero whose homeland was Troy. Homer describes Ganymede as the most beautiful of mortals. In the best-known myth, he is abducted by Zeus, in the form of an eagle, to serve as cup-bearer in Olympus. Some interpretations of the myth treat it as an allegory of...
, the Trojan prince turned god whom Zeus
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...
designated the cupbearer to the Greek gods (Jupiter's moon Ganymede
Ganymede (moon)
Ganymede is a satellite of Jupiter and the largest moon in the Solar System. It is the seventh moon and third Galilean satellite outward from Jupiter. Completing an orbit in roughly seven days, Ganymede participates in a 1:2:4 orbital resonance with the moons Europa and Io, respectively...
is also named after that individual). It has a very well determined orbit, and its next pass of the Earth will be at a distance of 0.359104 AU on 2011-Oct-13. It is also a Mars-crosser asteroid
Mars-crosser asteroid
A Mars-crosser is an asteroid whose orbit crosses that of Mars. The known numbered Mars-crossers are listed here. They include the two numbered Mars trojans 5261 Eureka and ....
, and will pass 0.02868 AU from Mars on 2176-Dec-16.
Physical characteristics
Owing to its early discovery date, Ganymed has a rich observational history. A 1931 paper published the absolute magnitude, based on observations to date, as 9.24, slightly brighter than the present value of 9.45. Ganymed is an S-type asteroidS-type asteroid
S-type asteroids are of a stony composition, hence the name. Approximately 17% of asteroids are of this type, making it the second most common after the C-type.-Characteristics:...
, meaning that it is relatively reflective and composed of iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
- and magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
-silicates. Spectral measurements put Ganymed in the S (VI) spectral subtype, indicating a surface rich in orthopyroxenes, and possibly metals (although if metals are present they are covered and not readily apparent in the spectra).
In 1998, radar observations of Ganymed by the Arecibo radio telescope produced images of the asteroid, revealing a roughly spherical object. Also around this time a study of several asteroids' visual lightcurve and polarization curves was conducted (the data for Ganymed is limited due to poor weather at the time). The study concluded that there was a weak correlation between the lightcurve and polarimetry curve as a function of rotation angle. Because polarization is dependant on surface terrain and composition, rather than the observed size of the object like the lightcurve, this suggests that the surface features of the asteroid are roughly uniform over its observed surface.
More recent observations of Ganymed's lightcurve, reported in 2007, confirm a rotation period of 10.314 ± 0.004 h
Hour
The hour is a unit of measurement of time. In modern usage, an hour comprises 60 minutes, or 3,600 seconds...
and a lightcurve amplitude of 0.12 mag
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
.
One occultation
Occultation
An occultation is an event that occurs when one object is hidden by another object that passes between it and the observer. The word is used in astronomy . It can also refer to any situation wherein an object in the foreground blocks from view an object in the background...
of a star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
by Ganymed was observed from California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
on August 22, 1985.