The fastest speed possible in the universe is the speed of light. This is achieved only by light and other forms of electromagnetic radiation, ie radio waves, X-rays, infrared radiation etc. The speed of light actually varies depending what it is travelling through. It is fastest when travelling through a vacuum where its velocity is 299,792,458 m/s (983,571,056 ft/sec). This means that, when you look at the Moon, you see it as it was about 1.3 seconds ago, and the Sun around 8.3 minutes ago.
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