EARTH 2

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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
http://www.msss.com/mars_images/moc/2003/05/22/
Images Credit: NASA/JPL/Malin Space Science Systems

The Earth and the Solar System formed about 4.6 billion years ago.

the solar system

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.

Earth's spin axis

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.

bulletOxygen is a very "reactive" gas that quickly combine with other elements.
bulletOn Earth however, its oxygen is maintained and produced by biological processes (life).

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).

Area of land: 148,326,000 km
2 (57,268,900 square miles), this are 29% of the total surface of Planet Earth.

Area of water: 361,740,000 km
2 (139,668,500 square miles), this are 71% of the total surface of the Earth.

97 percent is salt water; only 3 percent is fresh water.

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:

  1. North American Plate
  2. South American Plate
  3. Antarctic Plate
  4. Eurasian Plate
  5. African Plate
  6. Indian-Australian Plate
  7. Nazca Plate
  8. Pacific Plate

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
This is a Web site maintained by Spaceholdings.com.

http://www.nationsonline.org/oneworld/earth.htm
One World Nations Online is a large Web site containing lots of information about Earth.  It is not clear who is posting this information.

http://www.time.gov/
http://www.time.gov/timezone.cgi?Eastern/d/-5/java
Official U.S. Time

http://tycho.usno.navy.mil/
http://aa.usno.navy.mil/faq/docs/UT.html
U.S. Naval Observatory dealing with time