Recognize the uniqueness of Earth, being the only planet in the solar system with properties necessary to support life. The Solar System, is composed of the sun and the eight planets revolving around it. Among the eight planets, only one can support life: EARTH. There are two major requirements for a planet to become habitable. First: The star should survive long enough for its planet to develop life. Second: The planet should exist in a region where water could remain liquid. First: The star should survive long enough for its planet to develop life. The first requirement indicates that massive stars would have the least possibility to be habitable since they can only live for a relatively short period. Compared to medium-mass stars, such as the sun, which can survive long enough for life to develop. Second: The planet should exist in a region where water could remain liquid. The second requirement entails that the planet must be located in the Goldilock Zone. Being in the Goldilocks Zone indicates that due to the distance of Earth from the Sun, the amount of heat and solar energy received is just enough to make the temperature of Earth neither too hot nor too cold. For the inner planets, Mercury and Venus, since they are too close, the energy received from the sun is too much, contributing to the increase in temperature of their surfaces. For the outer planets, such as Mars, Jupiter, Saturn, Uranus and Neptune, their distances from the Sun are so far that the energy they receive is very little, making these planets very cold. Aside from their distance from the sun, planets may also have other features that are not suitable for life. Mercury, for example, experiences extreme temperature due to its slow rotation. It also has a very thin atmosphere that is not capable of capturing and maintaining the right amount of heat. Venus on the other hand, is very hot because it has a lot of active volcanoes that produce a very thick atmosphere. The thick atmosphere contributes to an increased greenhouse effect, making the surface temperature very high. In contrast with Venus, the fourth terrestrial planet, Mars, has very little volcanic activity. As a result, it has a thin atmosphere and cold surface temperature. The Jovian Planets, on the other hand, are mainly composed of gases. Therefore there is no land where organisms can live. With these features, it can be clearly seen how Earth is the only planet compatible with life. A planet with the right temperature enables water to remain in its liquid form, a necessary ingedient of life. A high temperature would change the phase of water from liquid to gas and a low temperature would change its phase from liquid to solid