The Asteroids are small, faint objects so they look like stars except that they move. Indeed the word asteroid comes from the Greek asteroeides which means "star-like". They are numbered in the order they are discovered and the discoverer is allowed to name them. There are thousands of them, but many of them are brighter than 12th magnitude and may be detectable in small telescopes even in light-polluted skies. However they can only be identified from their movement, so two pictures have to be taken of the same area of the sky at an interval of a few days and the two pictures compared. In the old days this was done with photographic plates and an instrumant called a Blink Comparator which enabled the two plates to be viewed alternately. True stars remain in the same positions, but a planet appears to jump between two positions and each image blinks. The same trick can be done these days with digital images by using what is called an Animated GIF file.
The asteroids mainly revolve around the Sun between the orbits of Mars and Jupiter, a position that was predicted by an empirical law relating the relative distances of the planets from the Sun known as the Titius-Bode Law which predicted there should be a planet at a distance of 2.8 AU. The largest is Ceres, officially designated now as a dwarf planet, and it is believed to contain at least 30% of the mass of the entire asteroid belt. A few are large enough that they are roughly spherical, but the majority are irregular-shaped bodies. Their compositions (as indicated by their spectra) fall into three main categories as follows.
C Carbonaceous containing carbon compounds and not unlike the carbonaceous chondrite meteorites.
S Silicaceous consisting of silicate minerals such as Olivine (a magnesium iron silicate).
M Metalic consisting largely of iron and nickel.
Below I list the few that I believe I have captured. Click on the name to see my "discovery" pictures, and a little information about the asteroid.
| Number | Name | ||
| 4 | Vesta | ||
| 43 | Ariadne | ||
| 69 | Hesperia | ||
| 196 | Philomela | ||
| 354 | Eleonora |