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Earth's Interior Divisions

Earth at Night
Credit: C. Mayhew & R. Simmon (NASA/GSFC), NOAA/ NGDC, DMSP Digital Archive

2004 August 22

Explanation: This is what the Earth looks like at night. Can you find your favorite country or city? Surprisingly, city lights make this task quite possible. Human-made lights highlight particularly developed or populated areas of the Earth's surface, including the seaboards of Europe, the eastern United States, and Japan. Many large cities are located near rivers or oceans so that they can exchange goods cheaply by boat. Particularly dark areas include the central parts of South America, Africa, Asia, and Australia. The above image is actually a composite of hundreds of pictures made by the orbiting DMSP satellites.

Layer Name	Outer Radius, km	Approximate Temperature, C	Composition
Inner Core	1229	7000	Solid Iron
Outer Core	3484	5000	Liquid Iron
Lower Mantle	5700	2000	Iron-rich Rock
Upper Mantle	6360	500	Iron-rich Rock
Crust	6371	0	Basalt, Granite

Credit: U. Hwang (GSFC/UMD), J.M. Lamming (NRL),

While Cas A is about 10,000 light-years away, light from the

supernova explosion first reached Earth just over 300 years ago.

Explanation: An unusual triangle of light

will be particularly bright near the eastern

horizon before unrise during the next two

months for observers in Earth's northern

hemisphere.

Zodiacal Light and the False Dawn
Credit & Copyright: Stefan Seip

2004 August 24

Supply Ship Approaches the

Space Station
Credit: ISS Expedition 9, NASA