They was until ... 1946
Nope, not anymore.
Answer:
1.1 year for any small rock.
Explanation:
- As the moon is frequently hit by the asteroid that directly impacts the surface and creates creators.
- As per the question if it takes about 20 of such impacts to remove the footprints lt by the apollo moon lander.
- Then it should take about one year as the moon has no atmosphere and is exposed to the solar winds.
Rock art? It's probably not the best answer, but apart from tools and weapons, it was the only thing I could think of.
Explanation:
un aumento gradual de la temperatura general de la atmósfera terrestre generalmente atribuido al efecto invernadero causado por el aumento de los niveles de dióxido de carbono, clorofluorocarbonos y otros contaminantes.