What are the Characteristics of earth as the only living planet?

Answer 1

Probably the most important characteristic of Earth in its support for life is the significant percentage of the surface covered with liquid water. This would not be possible except for Earth's favorable distance from the Sun where water can easily be liquid; and other characteristics like Earth's liquid core and magnetic field strong enough to protect the oceans from being evaporated into space by energetic particles and radiation from the Sun. The tidal effect of the moon is thought to have significant influence also.

The possibility of life elsewhere in the solar system where liquid water can exist (for example, in gas giant moons' oceans kept liquid by tidal heating effects) has not been entirely eliminated; nor has the possibility of life outside the solar system. Given the large number of earth-like planets just within our own galaxy (possibly as many as 40 billion), many consider the possibility statistically likely.

One other effect is of note - microscopic life and spores which have made their way into the upper atmosphere are thought to be pushed constantly outwards from the orbit of earth into the solar system; if they can survive the hostile freezing, desiccation and radiation of interplanetary space (like tardygrades) and land on a favorable environment it would be conceivable that micro-populations could thrive on bodies other than Earth.

Answer 2

Earth is the only known planet to host life due to its unique conditions such as a stable climate with liquid water, a protective atmosphere that shields from harmful radiation, and a diverse range of habitats that support a wide variety of organisms. Its position in the habitable zone of the solar system and the presence of essential elements like carbon, nitrogen, and oxygen also contribute to its ability to sustain life.