A number of classification schemes are currently in existence , and while they strive to retain some mutual consistency, quite a few asteroids are sorted into different classes depending on the particular scheme. This is due to the use of different criteria for each approach. The two most widely used classifications are described below:
The most widely used taxonomy for over a decade has been that of David J. Tholen, first proposed in 1984. This classification was developed from broad band spectra (between 0.31μm and 1.06μm) obtained during the Eight-Color Asteroid Survey (ECAS) in the 1980s, in combination with albedo measurements . The original formulation was based on 978 asteroids.
This scheme includes 14 types with the majority of asteroids falling into one of three broad categories, and several smaller types. They are, with their largest exemplars:
and the small classes:
Objects were sometimes assigned a combined type such as "e.g." CG when their properties were a combination of those typical for several types.
This is a more recent taxonomy introduced by Schelte J. Bus and Richard P. Binzel in 2002, based on the Small Main-Belt Asteroid Spectroscopic Survey (SMASS) of 1447 asteroids . This survey produced spectra of a far higher resolution than ECAS, and was able to resolve a variety of narrow spectral features. However, a somewhat smaller range of wavelengths (0.44μm to 0.92μm) was observed. Also, albedos were not considered.
While attempting to keep to the Tholen taxonomy as much as possible given the differing data, asteroids were sorted into the 24 types given below. The majority of bodies fall again into the three broad C, S, and X categories, with a few unusual bodies categorized into several smaller types:
A significant number of small asteroids were found to fall in the Q, R, and V types, which were represented by only a single body in the Tholen scheme.
In this Bus and Binzel SMASS scheme only a single type was assigned to any particular asteroid.
A few Near-Earth objects have spectra which differ strongly from any of the SMASS classes. This is presumably because these bodies are much smaller than those detected in the Main Belt, and as such may have younger less-altered surfaces or be composed of a less varied mix of minerals.
These classification schemes are expected to be refined and/or replaced as further research progresses. However, for now, the spectral classification based on the two above coarse resolution spectroscopic surveys from the 1990s is still the standard. Scientists have been unable to agree on a better taxonomic system, largely due to the difficulty of obtaining detailed measurements consistently for a large sample of asteroids (e.g. finer resolution spectra, or non-spectral data such as densities would be very useful).
The three main groupings of asteroids are thought to be related to the three basic meteorite types:
Saturn's Gallic group of satellites
The Gallic group is a dynamical grouping of the prograde irregular satellites of Saturn following similar orbits. Their semi-major axes range between 16 and 19 Gm, their inclinations between 35° and 40°, and their eccentricities around 0.53.
The International Astronomical Union (IAU) reserves names taken from Gallic mythology for these moons.
Similar mean orbital elements led the discoverers to postulate a common origin for the group in a break up of a larger body.
The diagram illustrates the Gallic group in relation to other irregular satellites of Saturn. The eccentricity of the orbits is represented by the yellow segments (extending from the pericentre to the apocentre) with the inclination represented on Y axis.
The four members of the group are (in order of increasing distance from Saturn):
The group was later found to be physically homogenous, all satellites displaying "light-red" colour (colour indices B − V = 0.91 and V − R = 0.48)
and similar infrared indices
Remarkably, recent observations revealed that the largest member of the group, Albiorix, displays actually two different colours: one compatible with Eriapo and Tarvos, and another less red. Instead of the common progenitor, it was postulated that Tarvos and Erriapus could be fragments of Albiorix, leaving a large, less red crater.
Such an impact would require a body with the diameter in excess of 1 km and relative velocity close to 5 km/s, resulting in a large crater with the radius of 12 km. Numerous, very large craters observed on Phoebe, prove the existence of such collisions in the Saturnian system's past.
Sulawesi
Sulawesi (formerly known as Celebes) is one of the four larger Sunda Islands of Indonesia, and is between Borneo and the Maluku Islands.
Sulawesi is the world's eleventh-largest island, covering an area of 174,600 km. The island is surrounded by Borneo to the west, by the Philippines to the north, by Maluku to the east, and by Flores and Timor to the south. It has a distinctive shape, dominated by four large peninsulas: the Semenanjung Minahassa; the East Peninsula; the South Peninsula; and the South-east Peninsula. The central part of the island is ruggedly mountainous, such that the island's peninsulas have traditionally been remote from each other, with better connections by sea than by road.
These are the ten largest cities in Sulawesi by population in 2010.
Flores
Flores is one of the Lesser Sunda Islands, an island arc. Its area is about . It goes east from the island of Java. There are about 1.5 million people in Flores. The largest town is Maumere.
Flores is east of Sumbawa and Komodo. It is west of Lembata and the Alor Archipelago. To the southeast is Timor. To the south is the Sumba strait. The Flores Sea is to the north.
On December 12 1992, an earthquake measuring 7.0 on the Richter scale occurred. It killed 2,000 people in the town of Maumere.
Sumbawa
Sumbawa is an Indonesian island in the middle of the Lesser Sunda Islands chain. It has Lombok to the west, Flores to the east, and Sumba farther to the southeast. It is in the province of West Nusa Tenggara.
Sumbawa is 15,448 km² (three times the size of Lombok). About 1.5 million people live there. It marks the boundary between the islands to the west, which were influenced by religion and culture spreading from India, and the region to the east that was not so influenced.
Sumbawa is inside the Pacific Ring of Fire. It is a volcanic island, including Mount Tambora (8°14’41”S, 117°59’35”E) which exploded in 1815, the most destructive volcanic eruption in modern history (roughly four times larger than the 1883 eruption of Krakatoa, between Java and Sumatra, in terms of volume of magma ejected). The eruption killed as many as 92,000. It also apparently destroyed a small culture of Southeast Asian affinity, known to archaeologists as the Tamboran kingdom. It launched 100 cubic kilometers of ash into the upper atmosphere, which caused 1816 to be the "year without a summer."
Clothing in Ancient Rome
Clothing in Ancient Rome is most commonly known by the toga and stola.
The cloth was made from wool, linen or hemp. Cotton and silk were also used, more rarely. Leather was also used. The kind of clothing showed status.
Tibia (video game)
Tibia is a MMORPG video game released in 1997. Three German science students, Stephan Börzsönyi, Guido Lübke, Ulrich Schlott and Stephan Vogler, thought of the idea for the game. It was made by the German company CipSoft.
Royal Library of Turin
The Royal Library of Turin is an important museum in Turin, Italy.
It was started by King Charles Albert of Sardinia in 1839.
Now it has 187,987 print volumes, 4,403 hand-written volumes (manuscripts), 3,000 drawings, 188 books made before 1501 (incunabula), 5,029 books from the 16th century, 20,987 pamphlets, and many engravings and maps. These works come mainly from collections from Savoy.