It's stars versus gas mountains in NGC 2174 and the stars are winning.
More precisely, the energetic light and winds from massive newly formed stars are evaporating and dispersing the
dark stellar nurseries in which they formed.
The structures of
NGC 2174 are actually much thinner than air and only appear as
mountains due to relatively small amounts of opaque interstellar dust.
A lesser known sight in the nebula-rich
constellation Orion, NGC 2174 can be found with binoculars near the head of the celestial hunter.
About 6,400 light-years distant, the
entire glowing cosmic cloud covers an area larger than the full Moon and surrounds loose
open clusters of young stars.
The above image from the
Hubble Space Telescope shows a dense interior region which spans only about three light years while adopting a
color map that portrays otherwise red hydrogen emission in green hues and emphasizes
in red and oxygen in blue.
Within a few million years, the stars will likely win out completely and the entire
dust mountain will be dispersed.