The Earth is the largest and most massive of the inner group
of planets.In the Solar System,
only the Earth is suited for advanced life of our kind; it lies
in the middle of the ‘ecosphere’, the region round the Sun
where temperatures are neither too high nor too low. Venus
lies at the extreme inner edge of the ecosphere, and Mars at
the extreme outer edge.

Earth Data:

Distance from Sun:
mean 149.5979 million km (1 a.u.)
max 152.0962 million km (1.0167)
min 147.0996 million km (0.9833)
Perihelion (2000): 3 January
Aphelion (2000): 4 July
Equinoxes (2000): 20 March, 07h 35m;
22 September, 17h 27m
Solstices (2000): 21 June, 01h 48m;
21 December, 13h 37m
Obliquity of the ecliptic:
23◦
.43942 (2000), 23◦
.43929 (2000)
Sidereal period: 365.256 days
Rotation period: 23h 56m 04s
Mean orbital velocity: 29.79 km s−1
Orbital inclination: 0◦ (by definition)
Orbital eccentricity: 0.01671
Diameter: equatorial 12 756 km; polar 12 714 km
Oblateness: 1/298.25
Circumference: 40 075 km (equatorial)
Surface area: 510 565 500 km2
Mass: 5.974 × 1024 g
Reciprocal mass, Sun = 1: 328 900.5
Density, water = 1: 5.517
Escape velocity: 11.18 km s−1
Albedo: 0.37
Mean surface temperature: 22 ◦C