f = PN/120 where f is frequency of power supply, P is number of poles in the machine and N = speed in rpm. So, Synchronous speed N = 120f/P. Thus for 50 Hz supply, 2 pole machine; synchronous speed = 3000rpm. ETRICAL
Within our solar system quite a bit of exploration has been done by spacecraft including orbiters and landers. Planets outside our solar system will be difficult or impossible to explore with spacecraft in our lifetimes, so astronomers and astrobiologists use other techniques to search for signs of life on these planets. In particular, astronomers are interested in planets within the habitable zone of stars.
Beyond the Solar System. This guide covers some of the highlights of the universe outside our own little cosmic neighborhood, from the inner workings of stars to the mysteries of dark energy and dark matter.