The highest heavens belong to the LORD, but the earth he has given to men." (Psalm 115:16)
"In the 15 years since the discovery of the first planet around a star other than our Sun, we have found more than 400 such exoplanets — but there is still no place like home." — Debra Fischer (Yale University astronomy professor). 2010 (Apr 29). "Signatures of life on other worlds." Nature 464:1276.
". . . the NASA spacecraft Kepler, which watches for a dimming in a star’s light as a planet crosses its face . . . was launched in 2009, and data from its first two years of operation have revealed about 3,000 candidate exoplanets. . . . Surprisingly, the cumulative data set does not contain a single Earth-sized planet at a habitable distance from its star . . . ." — Eric Hand. 2012 (Oct 18). "The exoplanet next door: Earth-sized world discovered in nearby α Centauri star system." Nature 490:323.
• Earth has a large supply of water, and our optimum distance from the Sun allows the water to exist in three forms — vapour, liquid, and ice. (Other planets have virtually no liquid water.)
• The two major constituents of our atmosphere, oxygen (21%) and nitrogen (78%) are balanced to make up the ideal medium for the support of life.
• Water vapour and carbon dioxide in our atmosphere produce a "greenhouse effect" moderating temperature extremes and allowing the survival of a variety of life forms.
• The nearly circular orbit of Earth and its relatively rapid period of rotation also limit temperature variations.
• Earth is provided with multiple safety shields to screen out the harmful components of the Sun's radiation. In addition to our distance from the Sun, shielding factors include the Earth's magnetic field and atmosphere, in particular the ozone layer.
• Elements essential to life (e.g., carbon, nitrogen, oxygen, phosphorus) are found in Earth's crust, hydrosphere, and atmosphere in quantities much greater than the average abundance observed in other parts of the universe.
• The inclination of Earth's axis of rotation (tilted 23.5° from a line perpendicular to the plane of Earth's orbit) provides for the seasons, permits all places on Earth to receive sunlight regularly, and probably prevents the locking of excessive amounts of water in polar glaciers.