Sánchez-Lavega Agustín
Escuela Superior de Ingeniería, Universidad del País Vasco, 48013 Bilbao, Spain.
Science. 2005 Feb 25;307(5713):1223-4. doi: 10.1126/science.1104956.
Determining a planet's rotation period can be difficult if the planet lacks a solid surface. However, for planets with an internal magnetic field, emissions at radio wavelengths are modulated by the planet's rotation rate. The latest results from the Cassini spacecraft seem to indicate that Saturn's rotation rate has slowed down by 6 minutes since the Voyager 1 and 2 spacecraft flew by the planet in 1980 and 1981, but it is unclear whether a slowdown has in fact occurred. Future data collected by Cassini may be able to resolve the question.
如果行星没有固体表面,确定其自转周期可能会很困难。然而,对于具有内部磁场的行星,其射电波长的辐射会受到行星自转速率的调制。卡西尼号航天器的最新结果似乎表明,自1980年和1981年旅行者1号和2号航天器飞越土星以来,土星的自转速率已经减慢了6分钟,但目前尚不清楚自转速率是否真的减慢了。卡西尼号未来收集的数据或许能够解决这个问题。