However, what causes them to be round instead of having different shapes? This article delves into the factors influencing planets’ spherical form, with a focus on gravity and mass distribution.
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All eight planets in our solar system, including the Sun, display a spherical shape. This is mainly a result of the immense gravitational force generated by their large masses, drawing all the matter towards their centers and smoothing out any irregularities. Smaller objects within the solar system may not achieve perfect sphericity as their gravitational forces are inadequate to reshape their structures.
The difference in objects’ escape velocities illustrates their varying gravitational influences. Earth’s escape velocity is approximately 11 km/s or 40,000 km/h, achievable only by the largest spacecraft due to its mass of 6 x 10^24 kg, resulting in its nearly spherical shape. On the other hand, Comet 67P, visited by the European Space Agency’s Rosetta and Philae spacecraft, has a much lower escape velocity of just 1 m/s, a speed easily surpassed by a simple jump. With a mass of 10^13 kg, a billion times lighter than Earth, Comet 67P has a shape resembling a rubber duck and is not spherical.
Objects with a diameter exceeding several hundred kilometers tend to adopt a more spherical shape. For instance, Earth, with a diameter of approximately 12,700 km, appears spherical, while Comet 67P, with a diameter of about 4 km, exhibits a different non-spherical form.
Scientists have contemplated the hypothetical concept of a cubical planet, though uncertainties persist. If such a planet existed, its rocky components would likely maintain a cubic structure, while the atmosphere and water would be confined to the central areas of each cube face. Life would likely be limited to the shores of central lakes, as the edges and corners of the cubes would form imposing mountain ranges.
(According to Britannica)