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PLANET EARTH This Web page
gives comprehensive information about out Planet Eart:
http://www.nationsonline.org/oneworld/earth.htm Basic
Facts.
North
and South America from Space The Earth and the Solar System
formed about 4.6 billion years ago.
The Sun is surrounded by four inner
planets (Mercury, Mars, Earth, and Venus) and five outer planets (Jupiter,
Saturn, Uranus, Neptune, and Pluto). http://www.nationsonline.org/oneworld/earth.htm
See also: http://vesuvius.jsc.nasa.gov/er/seh/astronomy.html All the planets in the solar system rotate counter-clockwise, except Venus. It is the only planet that rotates clockwise. Planet
Earth is the third closest planet to the Sun and the fifth largest overall. From a space travelers perspective, Earth is distinguished as having blue waters, green and brown land masses and white clouds. Earth has one moon. The earth revolves (orbits) around the sun once per year. The orbit is slightly elliptical in shape, with the sun at one of the foci of the ellipse. The orbit defines a plane containing the sun. Earth
orbits the sun at an average speed of 29.79 km/s (18.51 miles/sec), or about 107
000 km/h (about 67,000 miles/hour). Equatorial Circumference: 40,076 km
(24,902 miles). Earth’s Equatorial Diameter
12,756 km (7,926 miles). Earth’s
Equatorial Radius: 6,378 km (3,963 miles).
The sun’s radius is about 100 times larger.
Earth's average distance from the
Sun is 93 million miles (149 million kilometers). The distance from Earth to the
sun varies from about 147 million km to about 152 million km (that is, from
about 92 million to 95 million miles). The earth is closest to the sun
(perihelion) during January and farthest (aphelion) during July. The average distance between the sun
and the earth about 93 million miles is called 1 AU (astronomical unit.) This planet tilts 23.5° on its
axis, causing seasonal changes.
One
year on earth is 365.26 days long. The Gregorian Calendar added the extra day in a leap to compensate for this
discrepancy. One day is 23 hours, 56 minutes, and
4 seconds long. The earth rotates
once per day (24 hours). The rotation defines an axis of rotation, the North
Pole, the South Pole, and the equator. [Actually the
earth rotates slightly more than once per solar day, because the earth moves a
little bit in its orbit around the sun each day. As a result, any particular
place to face the sun most directly again, the earth must rotate a little bit
more than 360 degrees.] Earth
is slowing down - in a few million years there won't be a leap year. During
the course of a day, any particular location will move in a circle coinciding
with its latitude circle. The local time of day (defined in terms of the position of the sun in the sky) is the same everywhere along a longitude line. At any moment the sun illuminates half of the earth. The boundary between the sunlit and unlit halves of the earth is called the "circle of illumination" or the "terminator". Earth is the only planet in the Solar System known to harbor life. This is due to the atmospheric conditions able to provide life supporting conditions for living things. The Earth's layers are divided, each having distinct chemical and seismic properties. Earth is the densest major body in the Solar System. Atmosphere Earth has a strong magnetic field. Our planet's rapid spin and molten nickel-iron core give rise to an extensive magnetic field, which shields us from nearly all of the harmful radiation coming from the Sun and other stars. The Van Allen Radiation Belt is an
intense radiation zone. The first American satellite, Explorer 1, was launched
from Cape Canaveral in Florida on January 31, 1958, and discovered an intense
radiation zone, now called the Van Allen radiation belts, surrounding Earth. Other research satellites have
revealed that our planet's magnetic field is distorted into a tear-drop shape by
the solar wind, the stream of charged particles continuously ejected from the
Sun. We've learned that the magnetic field does not fade off into space but has
definite boundaries. And we now know that our wispy upper atmosphere, once
believed calm and uneventful, seethes with activity, swelling by day and
contracting by night. Affected by changes in solar activity, the upper
atmosphere contributes to weather and climate on Earth. Besides affecting Earth's weather,
solar activity gives rise to a dramatic visual phenomenon in our atmosphere.
When charged particles from the solar wind become trapped in Earth's magnetic
field, they collide with air molecules above our planet's magnetic poles. These
air molecules then begin to glow and are known as the auroras or the northern
and southern lights. Satellites about 35,789 kilometers
(22,238 miles) out in space play a major role in daily local weather
forecasting. These watchful electronic eyes warn us of dangerous storms.
Continuous global monitoring provides a vast amount of useful data and
contributes to a better understanding of Earth's complex weather systems. From their unique vantage points,
satellites can survey Earth's oceans, land use and resources, and monitor the
planet's health. These eyes in space have saved countless lives, provided
tremendous conveniences and shown us that we may be altering our planet in
dangerous ways. The
tail of the Great Comet of 1843 was 330 million km long. (It will return in
2356.) About
500 small meteorites fall to earth every year but most fall in the sea and in
unpopulated areas. There
is no record of a person being killed by a meteorite but animals are
occasionally hit. Earth's atmosphere is 78 percent
nitrogen, 21 percent oxygen, and 1 percent other gases. Earth's atmosphere protects us from
meteors, most of which burn up before they can strike the surface, as well as
harmful radiation. The presence of free oxygen on a planet is quite remarkable.
Without life on
Earth, there would be no free oxygen. Earth has a changing
weather pattern. Surface
of Earth Total Surface Area:
about 509,600,000 square km (197,000,000 square miles). The Earth's surface
is comprised of 71% water. This planet has five
continents or seven if you count North and South America as separate
continents and add Antarctica. Because of atmospheric conditions, Earth is the only planet that is capable of possessing water (in liquid form) on it's surface. This planet is covered with several mountain ranges. There is some volcanic activity on this
planet. Crust,
Mantle, and Core Earth consists of three layers: the crust,
the mantle, and the core. Unusual to the other terrestrial planets, the Earth's crust is divided into several separate solid plates which float independently on the hot mantle below (plate tectonics). At present, the eight major plates are: Plates carrying the continents migrate over the earth's surface a few centimetres (inches) per year, about the same speed that a fingernail grows. On average, 13,000 earthquakes are located each year It's core is composed mostly of iron (nickel/iron). The core's temperatures may be as high as 7500 K degrees, which is hotter than the surface of the Sun! There is zero gravity at the centre of earth. Other
Interesting Surface Facts Oceanography,
the study of oceans, is a mixture of biology, physics, geology and chemistry. The
magnetic north pole is near Ellef Ringes Island in northern Canada. The
magnetic south pole was discovered off the coast of Wilkes Land in Antarctica. The
Sahara desert expands at about 1km per month. More
than 70% of earth's dry land is affected by desertification The
largest iceberg ever recorded was 335km (208 miles) long and 97km (60 miles)
wide. Hurricanes,
tornadoes and bigger bodies of water always go clockwise in the Southern
Hemisphere and counterclockwise in the Northern Hemisphere. This directional
spinning has to do with the rotation of the earth and is called the Coriolis
force. Winds
that blow toward the equator curve west. During
a total solar eclipse the temperature can drop by 6 degrees Celsius (about 20
degrees Fahrenheit). The
tallest waterfalls in the world are Angel Falls in Venezuela. At 979 m (3,212
ft), they are 19 times taller than the Niagara Falls, or 3 times taller than the
Empire State Building. Although
the Angel Falls are much taller than the Niagara Falls, the latter are much
wider, and they both pour about the same amount of water over their edges -
about 2,8 billion litres (748 million gallons) per second. There
are 1040 islands around Britain, one of which is the smallest island in the
world: Bishop's Rock the
deepest mine in the world is Western Deep Levels near Charletonville, South
Africa. It is 4,2km (2.6 miles) deep. The
deepest point in the sea: the Mariana Trench off Guam in the Pacific Ocean; it
is 10,9 km (6.77 miles) below sea level. The
Dead Sea is 365 m (1,200 ft) below sea level. A
storm officially becomes a hurricane when cyclone winds reach 119 km/h (74 mph). More facts about Earth: http://www.space.com/scienceastronomy/101_earth_facts_030722-1.html http://www.nationsonline.org/oneworld/earth.htm http://www.time.gov/ http://tycho.usno.navy.mil/ |
