Name
|
- Earth is the only planet name not derived from Greek or Roman
mythology; it is an Old English term referring to the ground.
Other common names for Earth include Terra [Greek for soil] and Tellus
[Roman for fertile soil].
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Discovery
|
- Earth has been known, for obvious reasons, since ancient
times. There is, however, an interesting history about mankind's
perception of Earth's role in the universe. It is only in
relatively modern times that Earth is now known to be a planet much
like the others.
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Size & Mass
|
|
Orbit
|
| Radius |
149,600,000 km [average] |
1.00 AU
[average] |
| Eccentricity |
0.0167 |
|
| Inclination |
0.00 |
[by definition] |
| Revolution |
365.256 days |
|
| Velocity |
29.8 km/s |
|
| Obliquity |
23.45° |
|
| Rotation |
23.935 hours |
|
- The Earth's rotation slows by about two thousandths of a
second per century--this would only be noticeable over a long
period of time. This change has been somewhat corroborated
by fossil records, which indicated an 18-hour day nearly 900
million years ago.
|
|
Appearance
|
| Magnitude |
N/A |
|
| Angular
size |
N/A |
|
| Albedo |
0.37 |
|
- From a distance, Earth would not be very remarkable. It
would appear as a white dot, much like Venus, mainly due to
cloud cover. Land masses and oceans would not be
discernable until about the distance of the Moon.
- Magnitude and Angular size do not apply, as these are measured
from Earth, and not of Earth.
|
|
Conditions
|
| Temperature |
290 K |
|
| Atmosphere |
77% Nitrogen, 21% Oxygen |
|
| Appearance |
Wide variety of surface
features, oceans, lakes, and cloud cover. |
| Features |
Earth has a wide variety
of surface features, including mountains, volcanoes, craters, large
land masses, and oceans that cover ¾ of the Earth's surface. |
- Nearly all of Earth's surface features are due to a
combination of plate tectonics and atmospheric weathering.
Although Earth has been impacted by many objects in its history,
very few craters remain because of weather and volcanic
activity.
|
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Moons/Rings
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- Earth has no rings and one moon, Luna.
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Exploration
|
- Earth has been the most extensively studied object in the solar
system, for obvious reasons. There are countless weather,
imaging, and telecommunications satellites in Earth orbit.
- Nearly every space mission in history has involved at least a casual
observation of the Earth, and many missions have been dedicated solely
to Earth observation.
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Interesting Facts
|
- Earth is the only body in the solar system known to harbor
life. Mars and Europa [a moon of Jupiter] and the other
candidates that could possibly support life.
- The Earth's magnetic field, generated by its rotating molten iron
core, shields the surface from solar radiation. Life would
hardly be possible on Earth without this magnetic field.
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Links
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