Until 2006, Pluto was counted as the ninth planet in the solar system. It is much smaller than any of the other planets, and has a highly elliptical and inclined orbit unlike the others. Today, Pluto is no longer considered to be a planet, but is rather the first of a new category of objects called dwarf planets. Pluto's moon Charon is the largest in the Solar System, relative to the body it orb..

Neptune is the eighth planet, and - now that Pluto is no longer considered a planet - the farthest from the Sun. It is the second planet (after Uranus) to have been found in modern times. Neptune is a gas giant, composed mainly of hydrogen and helium, and has one large moon, Triton. Discovery and Observation Neptune was located through mathematical prediction, rather than by regular observation ..

Uranus is the seventh planet from the Sun, and was the first to have been discovered in recorded history. It is unique because its rotational axis is radically tilted towards its orbital plane, and its moons also have orbits that are tilted with respect to Uranus's orbital plane. Observation and Exploration Uranus orbits the sun at an average distance of 1.8 billion miles (2.9 billion km), or 19..

1. Refracting telescope a) Achromatic telescopeThe achromatic telescope is a refracting telescope that uses an achromatic lens to correct for chromatic aberration. b) Aerial telescope An aerial telescope is a type of very long focal length refracting telescope. c) Galilean telescope The design Galileo Galilei used in 1609. It used a convergent (plano-convex) objective lens and a divergent (plano..

Saturn is the sixth planet from the Sun and the second largest, after Jupiter. Like Jupiter, Saturn is a "gas giant" planet, composed mainly of liquid and gaseous hydrogen, with no solid surface. But what makes Saturn so unique and impressive is its spectacular system of rings.Observation and Exploration Saturn presents one of the most stunning views that can be seen through a small telescope. E..

Jupiter is the largest planet in the solar system, and by far the most massive. It contains over twice as much matter as all of the other planets combined. Jupiter is a very different planet from the Earth, or any of the other inner planets. It is composed mostly of liquid and gaseous hydrogen, and has no solid surface. For this reason, Jupiter is the first of the "gas giant" planets.Observation..