Earth

Can you find the Earth in this picture? (1990)

Mostly Harmless

Gneiss, tuff and a little wacke Geology

Know your schist

Catastrophic plate tectonics Geologic timeline British Isles Hydraulic fracturing Geomagnetism Fossil Yellowstone Water

Rock stars

Ian Plimer Farouk El-Baz Kurt Wise Emil Silvestru v - t - e

“”The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand. It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.

—Carl Sagan

Earth (Latin: Terra) is one of eight planets (specifically, a rocky one due to its solid surface, as with the rest of the first four planets, though the majority of the rock on our own planet is underwater) in the solar system orbiting a star, sometimes called Sol in random science fiction stories. While some believe there is intelligent life on Earth, others are too smart to really believe this.

Earth is also one of the four fundamental elements the Greeks philosophized about, the others being water, air and fire. Some people consider their philosophical ruminations to be somewhat naive. If you consider that they were doing said philosophizing a good few thousand years ago, and the four elements line up pretty well with solid, liquid, gas and plasma, perhaps they were not too far off the mark after all.

Fun facts about the Earth

Animation of 13 images, March 9, 2016, by NASA’s DSCOVR satellite showing the Earth's rotation, weather and lunar shadow in motion.

• Until the discovery of exoplanets, there was a great gap in planetary size between the largest-known terrestrial planet (Earth) and the smallest gas giant planet (Uranus based on mass and Neptune based on volume). Nobody had an explanation of why such was so. A great variety of planets orbiting stars other than the Sun fill the range in mass and volume between Earth and either Uranus or Neptune.
• Most of its inhabitants believe that the Earth is a sphere, although it is an oblate spheroid, a sphere just slightly appearing to have been "pushed in" a bit on the poles so the equator "bulges out" a bit more than on a perfectly spherical object. A highly vocal, loony, and nasally minority seem to think that it is flat, presumably squarish. This RationalWiki editor believes that it is a icosahedron.
• Despite the fact that "Earth" means dirt, most of Earth's surface is covered by water. Curiously, while water is absolutely vital to continued life as humans know it, most of the Earth's water, if consumed in sufficient quantities, would kill humans.
• The Earth's environment is seemingly quite fragile. However, since it is our God-given right to trash it, dammit we're gonna do it.
• According to one calculation, the Earth is close enough to the sun to be on the hot side of the habitable zone, but life (especially plants and cyanobacteria photosynthesizing carbon dioxide) prevents the climate from going haywire on the hot side.
• Everyone that has ever lived and everyone you have ever known has been from Earth. Deep, ain't it? Alien abductionists may disagree with this.
• Earth lost out to Mars when all of the planetary bodies of the Solar System voted for Most Likely to Support Life. But, who's laughing now?
• It is the only planet in the solar system not named after a Roman god/goddess in the English language. However, the dwarf planets Haumea and Makemake are named after Hawaiian and Easter Island deities respectively, whilst Eris is named after the Greek goddess of discord.
• Since Pluto was demoted from status as a planet, Earth is the only planet in our solar system to not be depicted in the symphonic suite The Planets by Gustav Holst.
• It is the only known planet with RationalWiki, Minecraft, feminism, and the music of Mozart.
• It is also the only known planet with crocodiles, MRAs, the Religious Right and $cientology.
• Its inhabitants are "Mostly Harmless"^{(caps intentional)}
• It has yet to create a sustainable civilization.
• Its inhabitants often work hard to distract from and derail progress towards greater consciousness.

Quantitative facts about the Earth

Radius (volumetric mean) = 6371.0 km Equatorial = 6378.1 km Polar = 6356.8 km Crust depth = 25 km (variable) Mantle thickness = 2860 km Core = 3480 km Mass = 5.97×1024 kg Atmosphere = 5.1×1018 kg Hydrosphere = 1.4×1021 kg Crust = 3.4×1022 kg Mantle = 4.0×1024 kg Core = 1.9×1024 kg	Distance from the Sun = 1.50×1011 m Distance from the Moon = 3.84×108 m Escape velocity = 11.186 km/s Bond albedo = 0.306 Surface temperature = 288 K (15°C or 59°F) Gravitational binding energy = 2.5×1032 J Moment of inertia = 8.02×1037 kg m2 Density = 5514.8 kg/m3 Atmosphere (surface) = 1.217 kg/m3 Crust = 2700 kg/m3 Mantle = 4500 kg/m3 Core = 11000 kg/m3

Future

Unless someone gets it right much earlier, it's expected that the increase of the Sun's luminosity as it ages will cause an increased weathering of minerals, lowering atmospheric CO₂ concentrations so much that in around 600 million years plants will begin to disappear as they will be unable to use photosynthesis. No plants means no animals or fungi, and roughly 1 billion years from now, just bacteria will remain. Meanwhile, that very same increasing luminosity will also mess with the Earth's climate, causing either a moist or a runaway greenhouse effect which will cause the evaporation of the oceans with water molecules being destroyed by the Sun's ultraviolet radiation in the stratosphere, the hydrogen being lost to space while the much heavier oxygen remains and the process according to Peter Ward and Donald Brownlee on their work The Life and Death of Planet Earth storms far more powerful than any current one and the dwindling oceans becoming both hotter and saltier (as salt will remain) as time goes by, severely messing with the remaining life on them and at the end leaving just bacteria adapted to such conditions there too.

In the former case, if the oceans boil away fast enough, Earth will be left as a pink and brown bone-dry wasteland somewhat resembling both Mars and Saturn's largest moon Titan with dunefields on its equator, salt-rich flats with scattered ponds marking the former place of the oceans, an oxygen-rich, Venus-like crushing, atmosphere at least for a while before such oxygen was absorbed by surface rocks, large volcanoes over mantle hotspots as both the only standing mountains, the others having been eroded away, and most visible signs of geological activity, and most of the little water just at the poles with maybe occasional rainstorms. In the latter case, which today is considered the most likely scenario, the slow evaporation of the oceans will saturate Earth's atmosphere with water vapor that will cause Earth's surface temperature to scream upward up to a hellish 1,600 K (1,330 °C; 2,420 °F), more than enough to melt its surface and wipe out any remaining life, and presumably later on once all that water was lost to space and thanks to all the carbon dioxide locked in rocks that such surface conditions would free Earth would become a Venus-like planet (ie, hellish but not as much.)

Given that no oceans could mean no plate tectonics, as water is often thought to be critical for it, heat may accumulate in Earth's interior until, as is thought to have happened on Venus, the planet's surface is covered in lava by extensive volcanism, killing whatever living things were still around. Alternatively, if plate tectonics stopped before the loss of oceans, erosion could transform Earth into a water-covered planet at least for a while.

Temperatures will eventually be so high that all life is expected to become extinct between at least 1.5 and 2.8 billion years from now, even if there's still the possibility in the case of the moist greenhouse happening of simple, hardy, life as extremophiles surviving on underground environments as deep in Earth's crust, ice-rich caves especially those located at high heights (ie, in mountains) close to the poles, etc. for a somewhat longer time and/or in the atmosphere, as had been thought to be happening in Venus. It's also expected that Earth's magnetic field will go away within a similar timeframe and that, if you had not enough, Moon's recession may cause the Earth's obliquity to go nuts within a similar amount of time, still putting more constraints on whatever had managed to survive to those times.

Nothing more of interest except temperatures on the rise due to the aging of the Sun is expected to happen until the Daystar exhausts its hydrogen supply 5 billion years from now and goes full red giant 2.6 billion years later, at which point it will absorb Earth destroying the planet in just minutes after 3,000 years of spiral-in to the Sun's innermost regions, but not before causing it to become a hell of a planet, including to have the Moon crashing back on Earth.

See also

• Age of the Earth — Yes, people really deny its age, hence this page's purpose of debunking that idea.
• Evidence against a recent creation — Evidence that our ball of dirt is really approximately 4.54 billion years old.
• Rotation of the Earth
• Earth Day
• Humans, one of the dominant species on this planet.
• Dogs, animals that one could argue are Man's equals in the food chain.
• Cats of all sizes, arguably the most bloodthirsty creatures on the planet.
• Goats, the dominant species on this planet.