The five planets most visible from Earth are Venus, Mercury, Mars, Jupiter and Saturn. These five are the closest planets to Earth. Without knowing how to identify these planets, people can mistake them for stars in the night sky.
The five planets visible from Earth were discovered before the telescope, and they can be seen by the unaided eye. Venus is the most easily identified planet because of its brightness and early appearance in the dawn sky. A good way to tell a planet apart from a star at night is whether or not it twinkles. Because of their distance from Earth, any atmospheric change causes a star's light to appear to bend or twinkle. While the sunlight reflecting off planets and their distance from Earth give them the appearance of emitting light as stars do, planets do not twinkle; their light is an illumination from the sun.
Once known as "wanderers," these five planets were noticed in the night sky because of their apparent wavering in position against a stoic background of stars. In fact, the word "planet" is derived from the Greek word for "wander." These five planets can be observed on any given night, though their brightness varies throughout the year because of their rotation around the sun.