Astronomer Frank Drake pioneered the ity of Evolution = Planets with evolved life Estimates are often given for the quantities on the left.
Since life evolved on Earth, it must likewise have happened elsewhere, either on planets or their moons.
The naïve assumption is that life will arise if we "just add water": Earth-like planet + water — spontaneous life This equation is falsified by over a century of biological research showing the deep complexity of life.
Scarcely is there a fact more certain than that matter does not spring into life on its own.
The nine solar system planets, from Mercury to Pluto, have been much-studied targets of the space age.
In general, a planet is any massive object which orbits a star, in our case, the Sun.
Some have questioned the status of Pluto, mainly because of its small size, but it remains a full-fledged planet.There is little evidence for additional solar planets beyond Pluto.Instead, attention has turned to planets which may circle other stars.Intense competition has arisen among astronomers to detect such objects.Success insures media attention, journal publication, and continued research funding.Just one word explains the intense interest in new planets—.