❓ why
Why do astronomers think dark matter exists if we cannot see it?
Quick Answer
Galaxies and clusters rotate and hold together as if they contain much more mass than visible matter alone can explain. That missing mass is attributed to dark matter.
The Full Story
Dark matter does not emit, absorb, or reflect light, but its gravity is clearly felt. Vera Rubin’s work in the 1970s showed that stars in spiral galaxies move as if there is extra unseen mass in the outer regions. Similar evidence comes from gravitational lensing and the motion of galaxies in clusters. Current models suggest dark matter makes up about 27% of the Universe.
Key Facts
1.Dark matter makes up about 27% of the Universe
2.Vera Rubin’s galaxy rotation studies were pivotal in the 1970s
3.Gravitational lensing provides additional evidence
YouTube Angle
Suggested video title for this topic:
"How do we know something invisible is there?"
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