Orion Arm — dust & structure
The space between the stars of the Orion Arm is filled with interstellar dust and gas — the raw material from which its nebulae and clusters form. This is a real fact. But the detailed shapes of the clouds, and the arm's band, are not mapped at this resolution and we see them only from inside the Galaxy, so what is drawn here is illustrative / modelled, never a photograph.
Science
What it is
- Interstellar medium
- Dust grains + hydrogen gas between the stars
- Role
- The material that collapses into stars and nebulae
- Local feature
- The Sun sits in a low-density 'Local Bubble' blown by past supernovae
How we know
- Note
- Interstellar dust is real — proved in 1930 when Robert Trumpler found distant clusters dimmed and reddened by it. Its bulk in the arm is genuine; the specific cloud SHAPES and the arm band shown here are modelled/illustrative (we observe from within, and the fine structure is not directly mapped). Shown in both view modes, dimmer in Realism.
Discovery & history
- Name
- The Sun lies in the Orion Arm (or Orion-Cygnus Arm / Local Arm), a minor spiral arm of the Milky Way named for the Orion constellation its nearby star-forming clouds lie toward.
Interstellar dust was proven real in 1930 when Robert Trumpler showed distant star clusters look dimmer and redder than distance alone allows. Radio surveys of hydrogen gas (from the 1950s) and, since 2013, ESA's Gaia mapping a billion stars have traced the Orion (Local) Arm's rough shape — a reconstruction from the inside, not a photograph.
Images
No official imagery available — this object has never been visited and no officially-licensed depiction exists.