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.
Although as many as 5,800 to 8,000 of the Milky Way's stars are visible from Earth with the naked eye, it is seldom possible to see more than 2,500 stars at any given time from any given spot.