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But the moon doesn't have an atmosphere. Surely there's nothing for the dust to "hang around" in. It would either achieve escape velocity or continue in an arc

But the moon doesn't have an atmosphere. Surely there's nothing for the dust to "hang around" in. It would either achieve escape velocity or continue in an arc until it hits the ground again.

SideburnsOfDoom 5y ago
> It would either achieve escape velocity or continue in an arc until it hits the ground again. Correct. IDK about impacts, but for rocket exhausts, the surprising result is that some of the kicked-up dust can achieve escape velocity, and "where it hits the ground" is "anywhere on the moon" - denser nearby, obviously, but there's no 100% safe distance anywhere on the lunar surface. https://www.theverge.com/2019/7/17/18663203/apollo-11-anniversary-moon-dust-landing-high-speed https://www.theverge.com/2019/7/17/18663203/apollo-11-annive...
knicholes 5y ago
Wouldn't the dust technically become the atmosphere? There is still gravity on the moon.
- SideburnsOfDoom 5y ago
  > douldn't the dust technically become the atmosphere? Only for short time, while it's vaporised into a gas by the impact. For that time it will join the rest of the "infinitesimal amount of gas" that forms a very tenuous atmosphere around the moon. https://www.nasa.gov/mission_pages/LADEE/news/lunar-atmosphere.html https://www.nasa.gov/mission_pages/LADEE/news/lunar-atmosphe...
- pdonis 5y ago
  > Wouldn't the dust technically become the atmosphere? No, because it's not a gas (dust has basically zero pressure) and it won't stay aloft at a constant or nearly constant altitude. It will either fall back to the surface or escape.
  - knicholes 5y ago
    I have a hard time believing that the dust would escape given the gravity of the moon.
ratsmack 5y ago
Dust is generally held in suspension by the air here on Earth, because of the air currents and because of air viscosity. With no atmosphere on the moon, I suspect the dust would not stay suspended above the surface very long.

But the moon doesn't have an atmosphere. Surely there's nothing for the dust to "hang around" in. It would either achieve escape velocity or continue in an arc until it hits the ground again.

SideburnsOfDoom 5y ago

> It would either achieve escape velocity or continue in an arc until it hits the ground again. Correct. IDK about impacts, but for rocket exhausts, the surprising result is that some of the kicked-up dust can achieve escape velocity, and "where it hits the ground" is "anywhere on the moon" - denser nearby, obviously, but there's no 100% safe distance anywhere on the lunar surface. https://www.theverge.com/2019/7/17/18663203/apollo-11-anniversary-moon-dust-landing-high-speed https://www.theverge.com/2019/7/17/18663203/apollo-11-annive...

knicholes 5y ago

Wouldn't the dust technically become the atmosphere? There is still gravity on the moon.

SideburnsOfDoom 5y ago
> douldn't the dust technically become the atmosphere? Only for short time, while it's vaporised into a gas by the impact. For that time it will join the rest of the "infinitesimal amount of gas" that forms a very tenuous atmosphere around the moon. https://www.nasa.gov/mission_pages/LADEE/news/lunar-atmosphere.html https://www.nasa.gov/mission_pages/LADEE/news/lunar-atmosphe...
pdonis 5y ago
> Wouldn't the dust technically become the atmosphere? No, because it's not a gas (dust has basically zero pressure) and it won't stay aloft at a constant or nearly constant altitude. It will either fall back to the surface or escape.
- knicholes 5y ago
  I have a hard time believing that the dust would escape given the gravity of the moon.

ratsmack 5y ago

Dust is generally held in suspension by the air here on Earth, because of the air currents and because of air viscosity. With no atmosphere on the moon, I suspect the dust would not stay suspended above the surface very long.