As an astrological term, earth is one of the elements which are associated with a sign of the zodiac.

Earth signs rarely react to a situation without thinking through it thoroughly and identifying a purpose or goal. earth signs are grounded and practical. They tend to be slow-paced (which may annoy others) so that they can enjoy what they are doing as well as get it right the first time.

The elements: Fire, Earth, Air, Water

Mass..........................1.317 x 1025 lb, 5.9743 x 1024 kg
Density.......................344.3 lb/cubic foot
Mean Radius...................3963 miles
Max Distance from Sun.........94,510,558 miles
Min Distance from Sun...........91,403,702 miles
Gravity relative to Earth ....1.00
Rotation Period.................23 h, 56 min, 4.099 s
Revolution time around Sun....365 d, 6 h, 9 min, 9.504 s
Orbital Velocity..............18.51 miles/second
Number of Moons.................1

A particularly good sci-fi novel by the one and only David Brin. I love this book for several reasons:

  • The depiction of the earth in 2038 is so realistic, you have no problem picturing people living in such a time. As Brin says in the afterword, it has to be different enough that people can believe it's the future, yet no so different that they can't believe it's only a few decades away.
  • Brin's predictions of the world data net in Earth have rung surprisingly true long before he predicted they would, in the book. I'm sure that some of the concepts Brin uses are inspired by Usenet as it existed when he wrote the book, but nonetheless, it's not hard at all to see how our modern day internet would envolve into something very close to what is portrayed in Earth.
  • As in many sci-fi novels, there are many characters, and each character has a separate story line, much like in Otherland. As they slowly converge, the climax of the story is just gripping, as the heroes struggle to use gravity lasers to extract micro black holes from the earth, to prevent the eminent apocalypse that they would cause.
  • The little epilogue is probably the coolest two pages I've ever read. The ending really makes you think, and basically offers a whole new theory as to how the universe came into existence.

Obviously, I would highly recommend this book anyone who remotely likes sci-fi.

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.


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.


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, ...


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
English title of a 1998 movie by Indian filmmaker Deepa Mehta. The movie is set in 1947 in Lahore which is now in Pakistan, but then was part of the British colony of India. The story tells of a group of friends--some Hindu, some Muslim, some Sikh--as they went through the creation of the states of India and Pakistan. The movie does a good job of representing the history of the time through the relationships of the young people in the town and how religion and nationalism change what otherwise were wonderful relationships.

It's a beautiful movie in cinematography as well as an important movie to see in these current troubled times--to understand the historical conflict between India and Pakistan, and also to undertand that Sikhs are not Muslims, even though they wear turbans. Also to show people that most Americans don't understand, and to show how some Western imperialism has contributed to the state of the world today.

The movie has English subtitles, with dialog in Urdu, Hindi, Arabic and other languages. Highly recommended.

The science fiction novel Earth by David Brin at 600 pages is a heavy book, not only in physical weight, but also in the depth and breadth of topics it covers. The book is set in 2038, "one possible future" as the author calls it. Brin attempts to create a world that is plausible enough to be our future, and yet imaginative enough to be eye opening.

The book starts out as a loose collection of essays, each giving a sociological caricature of our past, present, or future, and as the book progresses, these essays are tightly woven through a plot involving an apparently accidental impending doomsday of Earth, and its eventual prevention. Along the way, through actions, speculation, and thoughts by characters and groups, we are encouraged to think about what the Earth has today, and to appreciate it and treasure it. Various characters in the book speculate on the existence, search for, and interaction with extra-terrestrial life, genesis of life on Earth, struggle to live in and preserve (or destroy) their environment, and lightly experiment with multiple forms of speculative theology.

Societal characters include, gangs, corrupt politicians, and several groups of environmental extremists at both ends--including smugglers, poachers, Mother Earth worshipers, and Sun worshipers.

As typical for science fiction, some solutions to today's problems are offered, including a solution to political and financial corruption, a solution to common violent crime, and a partial solution to the continuing trend of the extinctions of species. Thoughts on creationism vs. evolutionism and their integration are explored.

The core of science about which the book's plot revolves includes a partial solution to the physics Theory of Everything, incorporating string theory and black holes.

Brin also expresses his pessimism on some problems ever being solved, or being solved in time anyway, including economical controlled fusion, political corruption, war, global warming, economical escape from Earth's gravity well, artificial intelligence, thinning of the ozone layer, human population growth, man vs. the ecosystem, and the nature of consciousness.

In short, the book Earth is a long deep speculation on the meaning of life and the planet Earth's place the universe.

Brin manages to covers a very wide range of topics, while tightly integrating them into the plot line, and yet still comes up with an interesting and somewhat surprising ending, making this book well worth its 600 pages.

The Earth (Hitchhiker's Guide To The Galaxy version)

The planet Earth was not a planet at all, but a gigantic computer of such amazing complexity that organic life formed part of its operational matrix. It was designed and programmed by another computer named Deep Thought, in order to find the Ultimate Question for a group of hyperintelligent, pan-dimensional beings who had recently found the Ultimate Answer to be "forty-two". It was built by the planet-manufacturing civilisation of Magrathea and placed in orbit around a miserable yellow star called Sol, deep in an unfashionable backwater of the Galaxy where it was most likely to be left alone. It was also, coincidentally, placed in a Plural zone, which can only be attributed to a planning oversight. The program was to take ten million years to run.

After eight million years had passed on the young planet, an arkload of fifteen million moronic Golgafrinchans, expelled from their home planet, crashlanded into a swamp in prehistoric Europe. Only a few hundred thousand Golgafrinchans survived the impact, but with their complete lack of respect for local wildlife and their admittedly superior technology, they eventually wiped out the indigenous cavemen - and a respectable portion of the Ultimate Question program, distorting the eventual output from the correct Question to read "What do you get if you multiply six by nine?"

Another two million years passed. The Golgafrinchans evolved and spread, forgot their extraterrestrial origins, and became the dominant life-form on planet Earth. Though the program still somehow continued to run, it had become utterly corrupted. Then, at lunchtime on an otherwise ordinary Thursday in early September 198-, just five minutes before the program was scheduled to be completed, the Earth was unexpectedly demolished by a Vogon Constructor Fleet. Though the reason given was that a hyperspace bypass was to be built through the Sol system, the actual reason was that Gag Halfrunt and every other psychiatrist in the Galaxy wanted to prevent anyone from ever finding out the Ultimate Question, and had employed the Vogons to do their dirty work.

The other Earth

There exists a near-infinite multiplicity of Universes, scattered across the vast spectrum or probability. In most of these universes there is a planet Earth. In many of these universes, Earth was demolished by the Vogons. In many others, it wasn't. Several years after the original Earth had been demolished, thanks to what has been described as "a fault line in the landscape of probability", a second Earth suddenly took the place of the first one, carrying on from the very second it had left off. A few seconds later the program ran to completion, but since Earth's hyperintelligent pan-dimensional overseers were not around to see it, nobody ever found out what the Question was.

All of the near-infinite multiplicities of the planet Earth were finally destroyed several years later still by a lost, confused Grebulon warship, which had been manipulated to do so via reverse temporal engineering on the part of the Hitchhiker's Guide to the Galaxy Mark 2. This ended the great experiment to find the Ultimate Question. The Guide Mk 2 had originally been researched, designed and created by Vogons, and funded by a staggering quantity of money provided by the amassed psychiatrists of the Galaxy.

For completeness: the Guide entry

The original entry for Earth in the Hitchhiker's Guide to the Galaxy read, due to space considerations and Earth's utter insignificance in every way, "Harmless".

Ford Prefect, a field researcher for the Guide, came to Earth in order to expand the entry. He intended to come for two weeks but ended up stranded for fifteen years, and in that time he wrote a very great deal about the planet - "text, diagrams, figures and images, moving desciptions of surf on Australian beaches, yoghurt on Greek islands, restaurants to avoid in Los Angeles, currency deals to avoid in Istanbul, weather to avoid in London, bars to go everywhere" (extract from So Long, And Thanks For All The Fish). This he transmitted off to the Guide offices towards the end of his stay. Unfortunately his submission was extensively cut down by the Guide's editing departments. For the most part of the Hitchhiker trilogy, the Earth was represented by the immortal phrase "Mostly Harmless".

Several years later, with Earth's baffling continuing existence, Ford's entry was restored in its entirety.

Buried in you
Primal release
Deep rooted
In your base
Fur, fire, and friction
Ancient memories
Telling tales
With my tongue
My teeth
Sinking into you
You release
Hearing heartbeats
As your thighs squeeze
Those mountains shake
Energy alchemy
Grounded and ethereal
Earth beneath my mouth

Earth (?), n. [AS. eor&?;e; akin to OS. ertha, OFries. irthe, D. aarde, OHG. erda, G. erde, Icel. jör&?;, Sw. & Dan. jord, Goth. aIrpa, OHG. ero, Gr. &?;, adv., to earth, and perh. to E. ear to plow.]


The globe or planet which we inhabit; the world, in distinction from the sun, moon, or stars. Also, this world as the dwelling place of mortals, in distinction from the dwelling place of spirits.

That law preserves the earth a sphere
And guides the planets in their course.
S. Rogers.

In heaven, or earth, or under earth, in hell.


The solid materials which make up the globe, in distinction from the air or water; the dry land.

God called the dry land earth.
Gen. i. 10.

He is pure air and fire, and the dull elements of earth and water never appear in him.


The softer inorganic matter composing part of the surface of the globe, in distinction from the firm rock; soil of all kinds, including gravel, clay, loam, and the like; sometimes, soil favorable to the growth of plants; the visible surface of the globe; the ground; as, loose earth; rich earth.

Give him a little earth for charity.


A part of this globe; a region; a country; land.

Would I had never trod this English earth.


Worldly things, as opposed to spiritual things; the pursuits, interests, and allurements of this life.

Our weary souls by earth beguiled.


The people on the globe.

The whole earth was of one language.
Gen. xi. 1.

7. (Chem.)


Any earthy-looking metallic oxide, as alumina, glucina, zirconia, yttria, and thoria.


A similar oxide, having a slight alkaline reaction, as lime, magnesia, strontia, baryta.


A hole in the ground, where an animal hides himself; as, the earth of a fox. Macaulay.

They [ferrets] course the poor conies out of their earths.

Earth is used either adjectively or in combination to form compound words; as, earth apple or earth-apple; earth metal or earth-metal; earth closet or earth-closet.

Adamic earth, Bitter earth, Bog earth, Chian earth, etc. See under Adamic, Bitter, etc. --
Alkaline earths. See under Alkaline. --
Earth apple. (Bot.)

(a) A potato.
(b) A cucumber. --
Earth auger, a form of auger for boring into the ground; -- called also earth borer. --
Earth bath, a bath taken by immersing the naked body in earth for healing purposes. --
Earth battery (Physics), a voltaic battery the elements of which are buried in the earth to be acted on by its moisture. --
Earth chestnut, the pignut. --
Earth closet, a privy or commode provided with dry earth or a similar substance for covering and deodorizing the fæcal discharges. --
Earth dog (Zoöl.), a dog that will dig in the earth, or enter holes of foxes, etc. --
Earth hog, Earth pig (Zoöl.), the aard- vark. --
Earth hunger, an intense desire to own land, or, in the case of nations, to extend their domain. --
Earth light (Astron.), the light reflected by the earth, as upon the moon, and corresponding to moonlight; -- called also earth shine. Sir J. Herschel. --
Earth metal. See 1st Earth, 7. (Chem.) --
Earth oil, petroleum. --
Earth pillars or pyramids (Geol.), high pillars or pyramids of earth, sometimes capped with a single stone, found in Switzerland. Lyell. --
Earth pitch (Min.), mineral tar, a kind of asphaltum. --
Earth quadrant, a fourth of the earth's circumference. --
Earth table (Arch.), the lowest course of stones visible in a building; the ground table. --
On earth, an intensive expression, oftenest used in questions and exclamations; as, What on earth shall I do? Nothing on earth will satisfy him. [Colloq.]


© Webster 1913

Earth (?), v. t. [imp. & p. p. Earthed (?); p. pr. & vb. n. Earthing.]


To hide, or cause to hide, in the earth; to chase into a burrow or den. "The fox is earthed." Dryden.


To cover with earth or mold; to inter; to bury; -- sometimes with up.

The miser earths his treasure, and the thief,
Watching the mole, half beggars him ere noon.

Why this in earthing up a carcass?
R. Blair.


© Webster 1913

Earth, v. i.

To burrow. Tickell.


© Webster 1913

Earth, n. [From Ear to plow.]

A plowing. [Obs.]

Such land as ye break up for barley to sow,
Two earths at the least, ere ye sow it, bestow.


© Webster 1913

Earth, n. (Elec.)

The connection of any part an electric conductor with the ground; specif., the connection of a telegraph line with the ground through a fault or otherwise.

⇒ When the resistance of the earth connection is low it is termed a good earth.


© Webster 1913

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