Details. as.character and is.character are generic: you can write methods to handle specific classes of objects, see InternalMethods. Further, for as.character the default method calls as.vector, so dispatch is first on methods for as.character and then for methods for as.vector.
But this is the number of stars we can see from the entire Earth and we should remember that one hemisphere of Earth is always in daylight, so really only about 2500 to 5000 stars are visible at night from any given point on Earth.
According to Dr Brent Archinal of the Astrogeology Team of the US Geological Survey in Flagstaff, Arizona writing in the May, 1997 issue of. , the human eye can see about 2,500 stars in the clearest of night skies. But usually only about 1,500 to 2,000 stars can be seen due to weather, pollution, etc, and fewer still in night skies of cities due to the additional factor of city lights.