What would happen if a planet's gravity drops?
"Living things grow taller"
"You can jump higher"
Those are not answers I looking for, what I wanna know is if the centre pulling force of a planet is dropping, what would happen to it's mantle, plates, as well as the atmosphere?
If the central pulling force, or gravity, of a planet were to drop, it would have significant effects on the various components of the planet such as the mantle, plates, and atmosphere. Here's an explanation of what would happen:
1. Mantle: The mantle is the layer between a planet's crust and its core. It is primarily composed of solid rock that behaves as a slowly flowing, ductile material over long time scales. If the planet's gravity drops, the mantle's response would depend on how the decrease in gravity is distributed across the planet. If the change is relatively uniform, it could lead to a slight expansion of the mantle, causing the planet's diameter to increase. However, if the change in gravity is localized, such as in specific regions of the planet, it could potentially affect the mantle's flow patterns and possibly trigger localized uplift or subsidence.
2. Plates: The Earth's crust is divided into several tectonic plates that move atop the semi-fluid asthenosphere of the mantle. A decrease in gravity would affect the plates in a couple of ways. Firstly, it could result in a reduced driving force for plate movement, slowing down plate tectonics. This could lead to decreased seismic activity, meaning fewer earthquakes and volcanic eruptions. Secondly, the changes in gravity distribution could cause variations in stress along plate boundaries, potentially altering the locations and intensities of tectonic activity in certain regions.
3. Atmosphere: Gravity plays a crucial role in maintaining a planet's atmosphere. It holds the gas molecules closer to the planet's surface, preventing them from rapidly escaping into space. A drop in gravity would weaken this holding force, which means that some lighter gases, such as hydrogen and helium, could escape more easily. Over an extended period, the loss of these gases could lead to atmospheric thinning or even a gradual loss of the atmosphere altogether. However, the changes in gravity would likely need to be substantial and sustained for this effect to become significant.
It's worth noting that these scenarios are based on theoretical considerations, as considerable changes in a planet's gravity are not common or easily achievable.