The term binary minor planet (BMP) is used for minor planets that have binary companions, e.g., (natural) satellites. The name suggests some degree of equality, but the term is commonly used for any minor planet for which a satellite is observed. Since the term "minor planet" is used for very small objects (anything larger than a meteoroid), there is some logic to this. Over 100 binary asteroids are known, the first whose binary nature was discovered being 243 Ida in 1993. Several binary trans-Neptunian objects (binary TNOs) are known as well.