... 22.Reference Frames . ... To derive the motion of a penny dropped inside an airliner moving at 600 miles/hr (about 1000 km/hr)--should we calculate it with respect to the interior of the airliner, or with respect to the ground? ... And if a similar penny is let go inside an orbiting spaceship--should its motion be calculated relative to the interior of the spaceship, or relative to the Earth outside? ... How do observations differ in the two frames--the airliner cabin and the Earth? ...
An astronaut in low Earth orbit moves in (approximately) a big circle extending around the Earth. ... That can be interpreted as stating that in the astronaut's frame of reference, all bodies are subject to two forces, gravity and the centrifugal force, and the two are in perfect balance, adding up to zero. ... Wheel-shaped space . ... The science-fiction film "2001: A Space Odyssey" featured spinning space station, whose rotation provided the crew with "artificial gravity." ...
Comet Shoemaker-Levy 9 was discovered photographically by the husband and wife scientific team of Carolyn S. and Eugene M. Shoemaker and David H. Levy on March 24, 1993, using the 0.46-m (18-in.) ... Its discovery was a serendipitous product of their continuing search for near-Earth objects , and the 9 indicates that it was the ninth short-period comet (period less than 200 years) discovered by this team. ... In other words, the comet, or at least parts of it, could very well hit Jupiter. ...