I'm NOT 100% sure about this answer but I think it's the Lines of Longitude
A planetary nebula is a (ring-shaped) type of nebula formed by an expanding shell of gas around an aging star. *a planetary nebula is a type of nebula*. im not completely certain though. i might be wrong.
Answer:
mid-ocean ridges
Explanation:
Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.
Hoped this helped
Russia. Is is the border of Europe very close to Asia
