This image of asteroid Gaspra was taken by the Galileo spacecraft in 1991. The asteroid's surface is found to be covered with more than 600 craters. Its very irregular shape suggests that the asteroid was derived from a larger body by nearly catastrophic collisions.

Although the total mass of all these small members of the solar system is less than 1% of the total mass of all major planets, their numbers greatly exceed the number of major planets. Astronomers estimate that there may be hundreds of thousands of small members orbiting the Sun.

During its examination of the asteroid Ida, the Galileo spacecraft discovered a second object, Dactyl - the first confirmed satellite of an asteroid. The much smaller moon is visible to the right of Ida.

The latest Sky Show “Small Solar System Bodies” will recount the courses and scientific basis of the discoveries of these small members and explain how astronomers study these extremely remote and small celestial bodies, the largest one being less than 3000 km in diameter.

In 2001, the NEAR spacecraft touched down on asteroid Eros, after transmitting 69 close-up images of the surface during its final descent.

Japanese Hayabusa spacecraft landed on near-Earth asteroid Itokawa in 2005 and collected samples from the asteroid for bringing back to Earth. This is the first asteroid sample return mission.

These small bodies may look unimportant. Yet, they may have significant impact on the life on earth. Comets may be the origin of life on earth. Asteroids, colliding with the Earth, may have brought about drastic climate change which led to the extinction of dinosaurs.

Most of the asteroids are found between the orbit of Mars and the orbit of Jupiter. However, some asteroids, known as Jupiter Trojans, share the orbit of Jupiter. They are located about 60 degrees from Jupiter.

The Deep Impact spacecraft travelled to comet Tempel 1 and released an impactor, creating a crater on the surface of the comet for scientists to analyse the constituents of the comet.

After the resolution of International Astronomical Union in August 2006, Pluto is demoted to a dwarf planet. Both Ceres and Eris are also classified as dwarf planets.

Spacecraft Giotto's encounter with Comet Halley provided the first ever opportunity to take images of a comet nucleus when Comet Halley returned in 1986.