HOW

DID

EARTH

GET

ITS

NAME?

The answer is, we don't know.

The name "Earth" is derived

from both English and German

words, 'eor(th)e/ertha' and 'erde',

respectively, which mean ground

But, the handle's creator is

unknown. One interesting

fact about its name: Earth 

is the only planet that wasn't

named after a Greek or

Roman god or goddess

For example, Saturn was named

after the Roman god of agriculture,

and Jupiter's name comes from

the King of the Roman gods

The Earth truly is a planet of extremes,

from ice-cold tundra to steamy rain

forests, from ocean trenches to snow-

covered peaks

Earth is unique among the known planets: it has an abundance

of water. Other worlds - including a few moons - have atmospheres,

ice, and even oceans, but only Earth has the right combination

to sustain life

PLATE TECTONICS KEEP THE PLANET COMFORTABLEPlate tectonics may be a phase in the evolution of planets that has implications for the habitability of exoplanets, according to new research

published this month in the journal Physics of the Earth and Planetary Interiors

Two of the things that make Earth unique in our solar system are that it

has plate tectonics – with the surface broken up into a number of tectonic

plates that drift around, moving continents and causing earthquakes – and life

Plate tectonics provides a mechanism for this global

thermostat. Most volcanism on the Earth occurs at

plate boundaries in response to plate tectonics. And

the most important volcanic products by mass – by

a large amount – are two greenhouse gases: carbon

dioxide and water. As they move over the Earth’s

surface, some plates get recycled back into the mantle,

at places like the Marianas Trench in the Pacific Ocean

Enormous amounts of water and

carbonate (the mineral form of CO2)

get recycled back into the interior

as they do

(700 to 10000 km)

(80 to 700 km)

(50 to 80 km)

(12 to 50 km)

(0 to 12 km)

Magnetic fields around planets behave

in the same way as a bar magnet. But at

high temperatures, metals lose their

magnetic properties. So it’s clear that

Earth’s hot iron core isn’t what creates

the magnetic field around our planet

Instead, Earth’s magnetic field is caused by a dynamo effect

On Earth, flowing of liquid metal in the outer core of the planet generates electric currents. The rotation of Earth on its axis causes these

electric currents to form a magnetic field which extends around the planet

Earth rotates once in about 24 hours with respect to the Sun,

but once every 23 hours, 56 minutes, and 4 seconds with

respect to other, distant, stars

Earth's rotation is slowing slightly with time; thus, a day

was shorter in the past

This is due to the tidal effects the Moon has on

Earth's rotation

Atomic clocks show that a modern-day is

longer by about 1.7 milliseconds than a

century ago, slowly increasing the rate at

which UTC is adjusted by leap seconds

Analysis of historical astronomical records shows

a slowing trend of about 2.3 milliseconds per

century since the 8th century BCE

At Earth’s equator, the speed of Earth’s spin is

about 1,000 miles per hour (1,600 km per hour)

The day-night has carried you around in a grand

circle under the stars every day of your life, and

yet you don’t feel Earth spinning

sixA sti no etatoR ot sruoH 4 2ekaT t’nseo DhtraE

A tropical year - also called many other things -

is approximately 365 days, 5 hours, 48 minutes,

and 45 seconds long. This equates to 365.242189 days

Tropical years are measured from either an equinox

or solstice to the next. You can measure from the

Vernal or Autumnal equinox, or the Summer and

Winter solstices

In reality, the length of a tropical year is calculated

by the amount of time it takes planet Earth to revolve

around the Sun. It's not exact because it differs from

year to year

A true tropical year can vary in length up to a half hour

For example, the year 2027 will last for 365 days, 5 hours and 39 minutes. Whereas the year 2032 will last for 365 days and 6 hours

- much longer

Furthermore, 100% accuracy is not always possible. When calculating the time of a tropical year from start to end, it's common to be

off by a few seconds or more

A YEAR

ON EARTH

ISN’T

365 DAYS

Earthquake Weather Is a Myth

"Each culture has a its own version of 'earthquake weather' to rationalize when and where a earthquake will hit," seismologist 

Dr. Lucy Jones of Caltech tells Popular Mechanics

"Earthquakes are below the surface and need a constant fault to happen and this has nothing to do with weather

"An earthquake is caused by a sudden slip on a fault. Tectonic plates are always slowly moving, but they can get stuck at their edges due to 

friction. When the stress on the edge of a tectonic plate overcomes the friction, there is an earthquake that releases energy in waves that

travel through the earth's crust and cause the shaking that is felt

The Pacific Plate consists of most of the Pacific Ocean floor, and also includes Baja California and the California coastline.

The North American Plate comprises most of the North American continent, including the inland parts of California, as well

as parts of the Atlantic and Arctic Oceans' floors. The primary boundary between these two plates is the San Andreas Fault

SEAS COULD RISE 2.5 FEET BY 2100The figures for both pathways are more pessimistic than those outlined by the UN intergovernmental panel on climate change (IPCC),

which predicts the worst possibility is a 1.1-metre rise by 2100

The gap reflects advances in climate science and differences in approach. The IPCC works largely through consensus among scientific

working groups, which tends to produce relatively conservative estimates

By contrast, the new survey – published in the journal Climate and Atmospheric Science – aggregates the views of 106 specialists,

who were chosen because they have published at least six peer-reviewed papers on the subject in major academic journals

As a result, the predictions are more representative of a range of views in the field.

The higher estimates highlight growing concern about the world’s two biggest ice sheets, in Antarctica and Greenland

Satellite data and on-the-ground measurements show these regions are melting faster than most computer models predicted

CLOUDS HELP REGULATE EARTH'S TEMPERATURE

Clouds play an important role in both warming and cooling our planet. Clouds give us a cooler climate on Earth than we would enjoy

without clouds

However, as Earth’s climate warms, we won’t always be able to count on this cooling effect

At any given moment, about two-thirds of our planet is covered by clouds. So it’s not too surprising that clouds play an important role

in Earth’s climate!

Louds affect climate in two major ways

First, they are an essential part of the water cycle. Clouds provide an important link between the rain and snow, oceans and lakes,

and plants and animals

Secondly, clouds also have an important effect on Earth’s temperature. But it’s a bit complicated: Clouds can both cool down and

warm up the temperatures on Earth

Clouds can block light and heat from the Sun, making Earth’s temperature cooler

Clouds within a mile or so of Earth’s surface tend to cool more than they warm. These low, thicker clouds mostly reflect the Sun’s heat.

This cools Earth’s surface

EARTH IS A HEAT ENGINE

Earth Is a Heat EnginThe Earth is a body of stored heat, radiating into space

This heat is associated with two things; one is that the very high temperature of the inner parts of the Earth are very high,

and the other is the result of heat generated due to radioactive decay of material in the deep Earth

Were it not for the second of these factors the Earth would long ago have frozen solid -- it has had plenty of time to cool from

its initial hot state

This internal heat, combined with the fact that we know from several lines of evidence discussed under Topic 2 that the Earth is not

internally rigid, causes the interior to be in continuous motion in a complex pattern of slow upwelling and downwelling that is becoming

clearer as seismic methods (Topic 4) reveal the internal structure of the Earth in increasing detail

THE

FIRST

OZONE

HOLE

IS

STILL

HEALING

Scientific evidence of the depletion of the ozone layer over the Antarctic was first presented in 1985, and in 1987 the Montreal protocol

was signed, binding world governments to reduce and phase out the harmful chemicals identified as causing the problem

The ozone layer is showing signs of continuing recovery from man-made damage and is likely to heal fully by 2060, new evidence shows

The measures taken to repair the damage will also have an important beneficial effect on climate change, as some of the gases that

caused the ozone layer to thin and in places disappear also contribute to warming the atmosphere. Phasing them out could avoid as

much as 0.5C (0.9F) of warming this century

Recovery from the holes and thinning caused by aerosol chemicals has progressed at a rate of about 1% to 3% a decade since 2000,

meaning the ozone layer over the northern hemisphere and mid-latitudes should heal completely by the 2030s, if current rates are

sustained

THE DAYS ARE GETTING LONGER �

BUT VERY, VERY SLOWLY

Scientists used a combination of astronomical theory and geochemical signatures buried in ancient rocks to show that 1.4bn years ago

the Earth turned a full revolution on its axis every 18 hours and 41 minutes

The number means that, on average, the length of the day on Earth has grown by approximately one 74 thousandth of a second per year

since Precambrian times, a trend that is expected to continue for millions, if not billions, of years more

As the Earth’s rotation gradually winds down, the moon moves further away

Writing in Proceedings of the National Academy of Sciences, Stephen Meyers at the University of Wisconsin-Madison and Alberto

Malinverno at Columbia University in New York calculate that over the past 1.4bn years the moon has drifted about 44,000km from

Earth to a distance of 384,400km

hT a s ne Ss tu ari rsV iner to heM Uer nA i v eer r se ehT

An estimated 10 nonillion (10 to the 31st power) individual viruses exist on our planet—enough to assign one to every star in the universe

100 million times over.

Viruses infiltrate every aspect of our natural world, seething in seawater, drifting through the atmosphere, and lurking in miniscule

motes of soil

Generally considered non-living entities, these pathogens can only replicate with the help of a host, and they are capable

of hijacking organisms from every branch of the tree of life—including a multitude of human cells

Yet, most of the time, our species manages to live in this virus-filled world relatively free of illness. The reason has less

to do with the human body’s resilience to disease than the biological quirks of viruses themselves, says Sara Sawyer,

a virologist and disease ecologist at the University of Colorado Boulder.  These pathogens are extraordinarily picky about

the cells they infect, and only an infinitesimally small fraction of the viruses that surround us actually pose any threat to

humans

EARTH IS RADIOACTIVE

Uranium, thorium and potassium are the main elements contributing to natural terrestrial radioactivity

The isotopes 228U, 235U, 232Th and 40K decay with half-lives so long that significant amounts remain in the earth,

providing a continuing source of heat

The slow decay of these isotopes also provides the basis for radiometric age dating and isotopic modelling of

the evolution of the earth and its crust

There is a complex interplay between their heat production and the processes involved in crust formation

Phenomena such as volcanism, earthquakes,

and large-scale hydrothermal activity associated

with ore deposition reflect the dissipation of heat

energy from the earth, much of which is derived

from natural radioactivity.

The higher levels of radioactive

elements during the early history

of the earth resulted in higher

heat flow.   A l l three of the

radioactive elements are strongly

partitioned into the continental

crust, but within the crust their

distribution is determined by

their different chemical properties

LIFE BELOW THE SEAFLOOR

In fact, water percolating into the crust forms the largest aquifer on earth. This sub-seafloor system contains a whopping two percent

of the ocean’s volume, and scientists believe it may be home to large amounts of microbial life

These tiny microbes are of global importance. Their activity in the sub-seafloor environment shapes the chemistry of the ocean and

its influence on the atmosphere

Little is known about the sub-seafloor environment or the hardy microbes who thrive there, under intense levels of pressure and far

from the rays of the sun

More will be clear soon, however, as Bigelow Laboratory scientists analyze data from an October cruise to the Mid-Atlantic Ridge.

Along this underwater mountain range in the Atlantic Ocean, the Earth’s tectonic plates are slowly spreading apart, providing scientists

with easier access to the rock in the ocean crust

There are thousands of known species of mosses. A hardy plant, it has been found in habitats ranging from the humid tropics to

the polar regions, fallen logs to lakes, rivers, and streams

In fact, moss has been found just about everywhere, except in salt water

Moss is a relatively uncomplicated plant, lacking the leaves, stems, roots, and buds we often associate with “vascular plants"

such as ferns, pine trees, and flowers. As a non-vascular plant, the body of moss has no roots; rather, it uses tiny threads to

anchor itself to the stones, trees, or ground where it grows

People have used mosses for a variety of purposes. During World War II, Sphagnum, a certain variety of moss, was used to

dress soldiers' wounds. In addition to absorbency, it was also found to have mild antibiotic properties. In Mexico, moss is used

as a Christmas decoration, and many Japanese gardeners cultivate mosses to add a sense of age and calmness to their gardens

MOSSES ARE EVERYWHERE

FEI L O NE K EA ARM TT HA

PHOT SS SG IBNI L

H ET

Earth is well equipped as a planet and ideally placed in our solar

system and galaxy to support life as we know it. The product of

some 4.6 billion years of cosmic construction, our planet is flush

with life thanks to a fortuitous set of conditions

The solar system is comfortably nestled in a safe harbor

between major spiral arms, and its nearly circular orbit helps

it avoid the galaxy’s perilous inner regions. There are

relatively few stars near the sun, reducing risks to Earth

from gravitational tugs, gamma-ray bursts, or collapsing

stars called supernovae

Ancient plantlike organisms in the oceans added oxygen to the

atmosphere and created a high-altitude layer of ozone that

shielded early land species from lethal radiation.

Stars more massive than the sun burn hotter and usually

don’t live long enough for planets to develop life. Less

massive, younger stars are often unstable and are prone to

blasting their planets with bursts of radiation

The interstellar cloud of gas and dust that gave rise to

Earth contained enough radioactive elements to power a

churning core for billions of years. This creates a magnetic

field that protects the planet from dangers like solar flares

Earth is tilted with respect to the sun, and teeters as it spins.

This tiny wobble can shift the climate from hot to icy every

41 ,000 years—and might vary more without the

moon’s stabilizing pull