Why are planets/moons/stars perfectly round?
Quite simply: gravity. Once you get above a certain size, gravity is strong enough that it will even deform an object into a sphere, which minimizes the gravitational potential energy on the object (everything is as close to the center as it can be). It isn't perfectly round though.
The Short Answer
Quite simply: gravity. Once you get above a certain size, gravity is strong enough that it will even deform an object into a sphere, which minimizes the gravitational potential energy on the object (everything is as close to the center as it can be). It isn't perfectly round though. Mountains an valleys produce (relativistically small) imperfections in the surface and spin produces a bulge, making the term for an object like the Earth an approximate oblate spheroid.
Analysis
Key Concepts: Object, gravity, quite
This explanation focuses on object, gravity, quite and spans 77 words across 4 sentences. The depth is typical for Space & Astronomy questions (category average: 68 words), striking a balance between accessibility and completeness.
What This Answer Covers
The explanation opens with: “Quite simply: gravity.” It then elaboratesultimately building toward a complete picture across 4 connected points.
How This Compares in Space & Astronomy
Ranked #182 of 500 Space & Astronomy questions by answer depth (top 37%). This falls in the detailed tier — above average depth. The explanation goes beyond surface-level but keeps things accessible.
Frequently Asked Questions
Is there a simple explanation for why planets/moons/stars perfectly round?
Quite simply: gravity. Once you get above a certain size, gravity is strong enough that it will even deform an object into a sphere, which minimizes the gravitational potential energy on the object (everything is as close to the center as it can…
How detailed is this explanation compared to similar Space & Astronomy questions?
This is an above-average answer at 77 words, ranked #182 of 500 Space & Astronomy questions by depth. The key concepts covered are object, gravity, quite.
What approach does this answer take to explain planets/moons/stars perfectly round?
The explanation uses direct explanation across 77 words. It is categorized under Space & Astronomy and addresses the question through 1 analytical lens.