Physical Scales

Below are illustrations of the sizes of planets and stars.

This image shows the relative sizes of the solar system's four terrestrial planets (Mercury, Venus, Earth and Mars) and the dwarf planet Pluto.
This image shows the relative sizes of the solar system's eight planets and dwarf planet Pluto. Note the Jupiter and Saturn are not perfect circles, but are elongated due to their gaseous composition and relatively fast rotation rates.
This image shows the relative sizes of the main objects in the solar system. Note that the Sun is larger than all the other objects by a vast amount. Thus its makes sense that the Sun is the only object in the solar system capable of squashing its core to such a high density and temperature that nuclear reactions can go on in its core, coverting  hydrogen to helium and releasing energy.

This image illustrates that although the Sun is the largest object in the solar system, it is relatively small compared to some other types of stars. Red Giant and Supergiant stars can be much larger than the Sun. They are undergoing a brief phase of their evolution that ultimately leads to their deaths as they evolve to become white dwarfs or Type II supernovae. In comparison, the size of white dwarf stars are similar to planets, and the size of the neutron stars that may be left behind after a Type II supernovae is typical of a city (1 km).

Star Spectral Type Stage of Evolution Surfance Temperature
Sun G2 Main Sequence 5,800 K
SiriusA A1 Main Sequence 9,900 K
Pollux K0 Red Giant 4,900 K
Arcturus K2 Red Giant 4,300 K

 

This image illustrates that although the Sun is the largest object in the solar system, it is relatively small compared to some other types of stars. The colors of the stars refect their temperatures. Hotter stars emit radiation at mostly bluer wavelengths, thus they appear bluer to our eyes. Cooler stars emit radiation at mostly redder wavelengths, thus they appear red to our eyes. Our eyes interpret equal amounts of radiation at different wavelengths as white, thus stars that appear white are intermediate in temperature.

Star Spectral Type Stage of Evolution Surface Temperature
Sun G2 Main Sequence 5,800 K
Rigel B8 Supergiant 11,000 K
Aldebaran K5 Red Giant 4,000 K
Betelgeuse M2 Supergiant 3,500 K
Antares M1 Supergiant 3,500 K