知识世界

Astronomy:Spacefiles — Earth

Rotating once a day， Earth takes a year to orbit the sun at a distance of 150 million kilometres. Earth is the largest inner planet， third from sun and first with a moon. Little more than a veneer， the top layer of Earth is the crust.

• 01

  Astronomy： Threat from Space

  
• 02

  Astronomy： Galileo and the Milky Way

  
• 03

  Astronomy： Spacefiles — Lord of the Rings

  
• 04

  Astronomy： Spacefiles — Venus

  
• 05

  Astronomy： Spacefiles — Sun

  
• 06

  Astronomy： The Story of Aviation

  
• 07

  Astronomy： Spacefiles — Galaxy

  
• 08

  Astronomy： History of the Race to the Moon

  
• 09

  Astronomy： Deep Impact

  
• 10

  Astronomy： Edwin Powell Hubble and the Expanding Universe