Dwarf planet
With the discovery of Pluto in 1930, most astronomers considered the Solar System to have nine planets, along with thousands of significantly smaller bodies (asteroids and comets). For almost 50 years Pluto was thought to be larger than Mercury, but with the discovery in 1978 of Pluto's moon Charon, it became possible to measure Pluto's mass accurately and to determine that it was much smaller than initial estimates. It was roughly one-twentieth the mass of Mercury, which made Pluto by far the smallest planet. Although it was still more than ten times as massive as the largest object in the asteroid belt, Ceres, it had one-fifth the mass of Earth's Moon. Furthermore, having some unusual characteristics, such as large orbital eccentricity and a high orbital inclination, it became evident that it was a different kind of body from any of the other planets.
List of transiting exoplanets
The most massive transiting exoplanet is KELT-1b which masses 27.23 M (making it a brown dwarf) while the least massive is Kepler-42d which masses less than 0.003 M or 0.9 M. The largest exoplanet known is HAT-P-32b which is 2.037 R. The smallest exoplanet known is also Kepler-42d which is 0.051 R or 0.57 R. The densest transiting exoplanet known is COROT-3b, which has density of 26.4 g/cm; the diffusest transiting planet known is Kepler-12b, which has density of only 0.111 g/cm. The longest period of any transiting planets is Kepler-1647b, which takes 1107 days to orbit its (double) stars. The shortest period is Kepler-42c, which takes just 0.45 days to orbit its star