There has not yet been a centaur photographed up close by a spacecraft, though there has been evidence that Saturn’s moon Phoebe, which was imaged by the Cassini probe in 2004, maybe a captured centaur.
Three centaurs, Chiron, 60558 Echorlus, and 166/NEAT 2001 T4, have been found to display cometary comas. Chiron and 60558 Echorlus are now classified as asteroids and comets. It is also possible that others centaurs are comets also.
Asteroids are metallic, rocky bodies without atmospheres that orbit the sun but are too small to be classified as planets. Asteroids are known as “minor planets”, tens of thousands of asteroids congregate in the so called main asteroid belt which is a vast, doughnut-shaped ring located between the orbits of Mars and Jupiter from approximately 2 to 4 AV (186 million to 370 million miles/ 300 million to 600 million kilometers).
Gaspia and Ida are main belt asteroids.
Asteroids are thought to be primordial material prevented by Jupiter’s strong gravity from accreting into planet-sized bodies when the solar system was born 4.6 billion years ago. The estimated total mass of all asteroids would comprise a body approximately 930 miles (1,500 kilometers) in diameter, less than half the size of the moon.
The understanding of asteroids is derived from three main sources: Earth-based remote sensing, data from the Galileo flyboys, and laboratory analysis of meteorites. Asteroids are classified in different types according to their Aledo. Compositions derived from spectral features in their reflected sunlight, and inferred similarities to known meteorite types.
Asteroids fall into 3 categories:
C-type (carbonaceous) - includes 75 percent and more of known asteroids. Composition is thought to be similar to the Sun, depleted in hydrogen, helium, and other volatiles.
S-type (silicaceous) - 17 percent of known asteroids. Composition is metallic iron mixed with iron and magnesium-silicates.
M-type (metallic) - includes the rest of the known asteroids composition dominated by metallic iron.
Notable asteroids such as Ceres, which is the first asteroid that was discovered, and it is the largest and most massive asteroid in the main asteroid belt. Its size and mass are sufficient to give it a spherical shape, much like a planet. It is so huge in comparison with the other asteroids. It is about 930 kilometers (578 miles) in diameter. It is similar in size to Saturn’s moons Tethy’s and Dione.
Some other notable asteroids are Pallas and Vesta, which are the second and fourth asteroids that were discovered. Pallas is the third largest asteroid, in terms of mass. Vestal is very much in comparison according to size, with Pallas.
433 Eros in the second largest known Near Earth Asteroid, the largest is 1036 Ganymed.
433 Eros is an Amor group asteroid, which means its orbital path poses no threat for Earth.