Binary number through each symbol, in increasing order. Before examining binary counting, it is useful to briefly discuss the more familiar decimal counting system as a frame of reference. Decimal counting uses the ten symbols "0" through "9". Counting begins with the incremental substitution of the least significant digit (rightmost digit) which is often called the "first digit". When the available symbols for this position are exhausted, the least significant digit is reset to "0", and the next digit of higher significance (one position to the left) is incremented ("overflow"), and incremental substitution of the low-order digit resumes. This method of reset
Binary asteroid Binary asteroid A binary asteroid is a system of two asteroids orbiting their common barycenter. The binary nature of 243 Ida was discovered when the Galileo spacecraft flew by the asteroid in 1993. Since then numerous binary asteroids and several triple asteroids have been detected. The mass ratio of the two components – called the "primary" and "secondary" of a binary system – is an important characteristic. Most binary asteroids have a large mass ratio, i.e. a relatively small satellite in orbit around the main component. Systems with a small minor-planet moon – also called "companion" or simply "satellite" –