The inner Solar System
The term planet is ancient, with ties to history, science, and religion, to name a few. All the International Astronomical Union approved planets in our Solar System are often visible to the naked eye, the exceptions are Uranus and Neptune which require binoculars or a telescope to be observed.
All the planets orbit the Sun in roughly the same plane, known as the ecliptic. As a result, they appear projected against the background stars in a band of constellations known as the Zodiac. How the planets move is described in a Tutorial by Paul Abel titled The motion of the planets which can be viewed here.
A follow up Tutorial has been writen by David Basey, called Loops in the Sky. Select here to view.
It is important to realise; that when viewing planets with the naked eye, they never appear as disks, but as points of light, the images in this article were all made using telescopes.
Should you wish to locate a planet for yourself, the British Astronomical Association regularly publishes “Sky Notes” including details of which planets are visible. In addition there are magazines and software available that will help point you in the right direction.
Mercury is not only the closest planet to the Sun at a average distance 36 milliom Miles (58 million km). It is also the smallest of the eight planets in our solar system with a diameter of 3,032 Miles(4,879Km). For every 2 orbits of the Sun, which takes around 88 Earth days, Mercury completes three rotations of its axis.
If you would like to learn more about Mercury. Chris Hooker who is the Mercury coordinator has writen a Tutorial called Mercury – the iron planet. Which can be viewed here.
Venus is the second planet from the Sun and the third brightest object in Earth’s sky after the Sun and Moon. The average distance from the Sun is about 67,000,000 miles (108,000,000 km). Venus is also slightly smaller than our Earth with a diameter of 7,520.8 mi (12,104)km. Venus and Uranus are the only planets that rotate on there axis in a clockwise direction.
Paul Able is the Director of the BAA Mercury and Venus Section who can be contacted here
The Outer Solar System
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