Our Sun and eight planets with their moons make up what astronomers call the “Solar System”. Although our Solar System is not the only one in the galaxy, scientists have not yet found the one like it. Each planet in the Solar System is as unique as the system in which it orbits. As a matter of fact, eight planets have very few attributes in common. They similarly orbit around the Sun, and they have largely the same chemical compositions. Beyond those two properties, the planets contrast far more sharply than they neatly compare.

The Sun’s gravity and magnetic field, called the “heliosphere”, envelop the major planets and all the dwarf planets in the Solar System. Although we frequently represent the planets’ orbits as circular, the major planets actually trace cosmic ellipses as they rotate around the Sun.

The planets take their names from Roman gods and goddesses. Of course, “Jupiter”, by far the largest of the eight planets, is named for the King of the Roman gods. Saturn, frigid and ice-bound almost beyond measure and imagination, paradoxically carries the name of the Roman god of agriculture. Mars, relatively small and desolate, carries the name of the Romans’ war god.

Until 1977 scientists thought only Saturn had “rings” – vast planes of ice and rocks suspended in orbit around them. Further investigation has shown that Uranus and Neptune also have ring systems. Naturally, their ring systems are not so pronounced as Saturn’s, because they are proportional to the two much smaller planets.

Astronomers refer to the bodies we generally call “moons” as “satellites”, and our moon has generally the same characteristics and properties as the other 139 satellites in the Solar System: it orbits the Earth as the Earth orbits the Sun, held in its elliptical pattern around the third planet by gravity and magnetism much like the Sun holds the planets.

In the last several years debate has raged over Pluto’s status: does it qualify as a planet, or does it fall into some other category of celestial objects?

In the course of the debate over Pluto the International Astronomical Society (IAS) the governing body that sets standards for measurements, observations, and discoveries changed the definition of and criteria for a planet. In order to meet official planet standards, a celestial body must orbit the Sun, have sufficient gravity to maintain a uniformly spherical shape, and clear its own orbit. After the IAS established its current standards, Pluto no longer met the requirements. Astronomers, after changing their assessments several times, finally classified Pluto as a “dwarf planet”.

Pluto travels in a little cluster of celestial objects very much like it, and astronomers developed an official classification for the whole group, calling these objects “plutoids”. They have gravity and hold their shape as they orbit the Sun, but they have not cleared their orbits. Many astronomers have become fascinated with the plutoids, arguing that insight into their development and evolution will contribute to proving “The Big Bang Theory”.

Although astronomy is the oldest science, it continues to be at the forefront of not only scientific thought, but that of the public at large too. Who has not looked up at the galaxy while walking home late at night and wondered? Having said that though, the ancient people of certainly the northern hemisphere, but probably both, knew the movements of the stars and planets better than most of us do nowadays.

They understood then, thousands of years ago, that the majority of stars appear to rise in the Eastern skies at night and travel on circular paths. They also noticed that some ‘stars’ were ‘wanderers’ (we call them planets) and that sometimes they went ‘against the flow’.

They also named groups of stars that we now call constellations or even galaxies and knew that those visible in the winter were different from those visible in the summer.and that others were visible all year round. The average common man of 5,000 – 10,000 years ago almost certainly knew more about the movement of the celestial bodies than the average common man of today does. (I mean men and women here, of course).

They learned how to calculate or at least locate the extremities of the sunrise and went to extraordinary lengths to mark those positions with huge stone structures, such as Stonehenge in the United Kingdom, probably to facilitate the location of certain positions of the sun or other planets or stars, which may have been important to their religious beliefs or crop cycles.

In 1609, Galileo invented the first artificial device for studying the stars and planets. It was the first astronomical telescope and through it he was able to observe things millions of miles away that no one had ever seen before. Because of the deductions he drew from his observations, he clashed with the Roman Catholic Church and was often in serious danger for his life, so radical were his discoveries.

But mankind was not intimidated, and since then we have gone on to build ever bigger and ever better telescopes with which we can even detect radio waves, microwaves, X-rays, infrared waves and gamma waves from outer space. Forty years ago, we even travelled to our Moon. and we have sent probes to eight of the nine planets in our Solar System, as well as to several comets and asteroids.

Where are we going next? That decision was always up to the government of the United States and the old Soviet Union, but now there are other players in the field. What will China or India want to explore with their possibly slightly different outlook on life? Or will it be just a question of financial benefit?

The world may be in a state of flux and power may be shifting from its traditional seats, but it has not diminished interest in questions that scientists think can only be answered in space. These are exciting times in the science of astronomy, but then man has always found astronomy exciting.