Here is a collection of
geophysical data, with some overlap with previous entries. These are garnered from
The Guinness Book of Answers, which is usually both precise and accurate in such matters. No doubt the same figures are also noded elsewhere under more specific topics, but a general survey might be useful.
Dimensions
Equatorial diameter: 12 756.274 km
Polar
diameter: 12 713.505 km
Equatorial
circumference: 40 075.02 km
Polar circumference: 40 007.86 km
The
metre was originally defined as one ten-millionth part of the polar
quartercircumference, so this is easy to remember.
The north polar
radius is 45 m longer than the south polar radius.
The
equator is elliptical, with its long axis at about
longitude 37° W being 159 m longer than the short
axis.
The earth is not perfectly round, nor perfectly
ellipsoidal, nor even the perfect
oblate (
pear-shaped) ellipse defined by the preceding figures. The greatest local variations of the surface from the
ellipsoid are an
elevation of 75 m near Papua New Guinea and a
depression of 105 m south of
Sri Lanka.
Composition
The
lithosphere (continental
crust) is about 80 km thick; below that is a rock
mantle about 2800 km thick; the
outer core is liquid and predominantly iron, with a radius of 3500 km; and the
inner core is solid iron probably in
crystalline form, with a radius of 1200 km. (I'm not clear whether the outer core radius includes that of the inner core it encloses.)
The centre of the earth is estimated to have a density of 13 000 kg m−3, a pressure of 360 GPa, and a temperature of 4500°C.
The lithosphere has the following abundance of elements:
46.60% oxygen, 27.72% silicon, 8.13% aluminium, 5.00% iron, 3.63% calcium, 2.83% sodium, 2.59% potassium, 2.09% magnesium, 0.44% titanium, 0.14% hydrogen, 0.095% manganese, 0.070% phosphorus, 0.065% fluorine, 0.026% sulfur, 0.025% carbon, 0.017% zirconium, 0.013% chlorine, 0.009% rubidium, 0.002% nitrogen, 0.001% chromium, ...
Atmosphere
The innermost layer, the
troposphere, is where most clouds and
precipitation live. It extends about 7 km up at the poles and 17 km up at the equator; in middle
latitudes its height varies with pressure, higher pressure meaning a higher
tropopause or limit.
Beyond the tropopause is the stratosphere, up to about 50 km. Temperatures increase in this region as you go outward, up to a maximum of about −3°C. Nacreous clouds live here.
Beyond that is the mesosphere, out to about 85 km, the mesopause, and temperatures drop rapidly down to about −110°C. Here be noctilucent clouds.
The thermosphere or heterosphere extends from the mesopause out to about 500 km. This is strongly affected by solar radiation, and reaches a temperature of 1480°C during the day during maximum activity, or 225°C during the night low down in the thermosphere during minimum solar activity.
Beyond that is the exosphere, where the atmosphere is so tenuous as to be space.
Highest points
Mt Everest 8848 m
Mt Everest south summit 8750 m
K2 8610 m
Kangchenjunga 8597 m
Lhotse 8511 m
Highest outside the
Himalayas and connected Asian ranges is
Aconcagua, Chile/Argentina border, at 6960 m.
This is from memory, not the book, but the peak reaching furthest from the centre of the earth is
Cotopaxi in Ecuador, because it's on the equatorial bulge.
For comparison, highest on other continents:
Denali (or Mt McKinley; North America) 6194 m
Kilimanjaro (Africa) 5894 m
Elbrus (Europe) 5663 m
Vinson Massif (Antarctica) 5140 m
Mauna Kea (Oceania) 4205 m
Mt Kosciuszko (Australia) 2230 m
Again from memory, Mauna Kea in Hawaii is the highest in the world from base to peak, because its base is deep in the ocean.
Lowest points
Challenger Deep,
Mariana Trench 11 033 m (reported), 10 924 m (confirmed)
Tonga-Kermadec Trench 10 850 m
Kuril-Kamchatka Trench 10 542 m
Galathea Deep,
Philippine Trench 10 539 m