A constellation refers to a particular pattern of stars that can be observed in the sky. It is important to note that a constellation does not necessarily consist of equidistant stars from the earth, as mentioned in option 2. Option 1, which states that a constellation consists of equidistant stars, is incorrect. Stars within a constellation can vary in their distance from Earth, and their appearance of being aligned in a pattern is due to the perspective of observation from Earth.

Option 3 is incorrect because constellations are not formed by planets of our solar system. Constellations are formed by stars. While planets can be seen in the night sky, they do not contribute to the formation of constellations.

Option 4 is also incorrect because constellations are not formed by satellites. Satellites are man-made objects that orbit Earth or other celestial bodies, and they do not play a role in the formation of constellations.

Therefore, option 2 is the correct answer, as it accurately describes a constellation as a pattern of stars that may not be equidistant from the Earth in the sky.