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Planet Earth
The Earth is the third
planet from the Sun. For the innumerable living inhabitants
of this sphere, including more than six billion humans,
it is the equivalent of a source of life.
The Greeks referred to
the Earth as Gaia: mother. It is clear that the intimate
relationship between the planet and living beings
produced a close link between humans and their habitat,
which we have given many different names: Earth, terre,
pamint, tero, erde, aarde, jorden, maa, zeme, semlja,
gaea, dhara, vuravura, eretz, jeegoo, ard...
How old is Earth? Between
4.5 and 4.6 billion years, say those who use the estimated
age of the solar system as the reference point.
We did not always have
a clear notion of "planet". In the past there were
numerous interpretations about the characteristics
of Earth, with some believing it was flat, and others
denied it had any relationship with its surroundings.
But at different points
around the Earth, the first scrutinizers and investigators
of the cosmos found the key. Now we know much more.
For example, its mass is 6x1,021 tons and its diameter
is 12,756.3 km.
Information about the Earth
abounds on the Internet. Many websites are dedicated
to "Earth Sciences", and some of the most informative
are about geology, defined by one site as the study
of the process of the planet's formation, the materials
of which it is composed, its history and its changes
over time.
There are also educational
sites about our planet, its role in the solar system,
and there are a lot of good resources from NASA, including
incredible images.
Nine
Planets: Earth
The
Earth - Other Languages
Our
Planet: Earth
Discovery:
Earth Journeys
NASA:
Earth Observatory
NASA:
Images of Earth
NASA:
Earth from Outer Space, Photos by Astronauts
NASA:
Planets - Earth
Biodiversity
Biological diversity, or biodiversity,
is the Earth's greatest wealth. Billions of years
ago began the evolutionary process that created the
variety of life on the planet today, the conservation
of which is one of humanity's biggest challenges.
The world's governments were
convened to make an effort to reduce threats to this
great wealth in the Convention
on Biological Diversity, drafted in 1992. But
achieving the goals stipulated by the treaty is still
a pending responsibility. Some countries, like the
United States and Afghanistan, have not even ratified
it, according to information found on the Internet.
The website of the Secretariat
of the Convention provides basic information for understanding
the issue, based on the notion that the biological
diversity we observe today is the fruit of billions
of years of evolution, shaped by natural processes
and increasingly influenced by human beings.
The variety of nature is evident
today in the fact that 1.75 million species have been
classified. However, experts say there could be as
many 13 million species, taking into account the flora
and fauna that have not yet been identified. And some
believe the number could reach 100 million.
Organizations like the All
Species Foundation seek to identify all forms
of life. It is a big challenge, considering that the
current rate of classification is around 15,000 per
year.
Biodiversity began to change
radically 10,000 years ago, with the beginning of
agriculture. And then began to accelerate three centuries
ago, with humanity's era of industrialization. Species
extinction, largely a natural process, sped up exponentially.
The World Conservation Union-IUCN,
publishes a "Red
Book", and the latest edition, from 2001,
stresses that there currently are 11,046 species in
danger of extinction.
At the international level, there
are numerous initiatives aimed at fighting the deterioration
of biodiversity, which is reflected in the many
websites dedicated to the issue. The United Nations
Environment Program (UNEP) sponsors a conservation
monitoring project, World
Conservation Monitoring Center and a trade convention
on protected species, CITES.
And then there is the World
Resources Institute, which makes periodically
evaluations about the situation of the Earth's living
organisms.
But the road to travel in preserving
biodiversity is still a long one. The variety of life
forms must be taken into account, as well as the scale
of organization of the species, including humans,
from genes to ecosystems.
Convention
on Biological Diversity
Secretariat
on the Convention on Biological Diversity
IUCN:
World Conservation Union - The Red Book
World
Resources Institute
Portal:
Virtual Library of Ecology and Biodiversity
UNEP:
Convention on International Trade in Endangered Species
of Wild Flora and Fauna (CITES)
UNEP:
World Conservation Monitoring Center (WCMC)
All
Species Foundation: seeks to inventory all species
of life
Yahoo!:
Directory on biodiversity
The Moon
The moon is often described as
a natural satellite of Earth, as it is condemned to
orbiting our planet. This link generates an important
force, the effects of which are most evident in the
changing tides of the oceans.
But in addition to influencing
the level of the seas, an effect that has economic,
social and environmental consequences, the moon has
always fascinated humans, who since time immemorial
have incorporated it into mythology, religion and
study. After all, the moon is always there.
The moon has served, for example,
to create calendars
that have allowed humans to track time since the ancient
era.
The
moon is 384,000 km from the Earth and has a diameter
of 3,476 km. It has a rough geography, spotted with
craters caused by the impacts of meteorites. The largest,
known as Newton, is 113 km across.
The origins of the moon remain
a mystery, but there are several theories. One is
that an impact of body from outer space with the Earth
produced enough material to form the moon. In any
case, it is believed to have occurred some four billion
years ago.
Because the moon is smaller than
the Earth, its gravitational pull has less effect
on objects on its surface. A person would feel six
times lighter, and a jump of one meter on Earth would
be 5.5 meters on the moon.
That fact has been proved because
the fascination with the moon prompted the world's
major powers to create the technology to send humans
to the moon. This occurred
in 1969, but the last
mission was in the 1970s, and since then there
have been no more missions to that "natural satellite".
The Internet holds a great deal
of information
about the moon. There are those that explain its characteristics
and unique qualities, those that explain its role
in eclipses, and those that invite you to navigate
cyber-space in search of greater knowledge.
NASA:
Moon Page
Portal:
Moonpeople, an introduction to the Moon
Apollo
11: Moon Landing, July 20, 1969
Lunar
Calendar
Moon
Facts: How much would you way on the moon?
Lunar
Eclipses for Beginners
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