The current best estimate for the total mass of the Milky Way is:
🌌 ~1.0–1.3 trillion solar masses
That is:
(1–1.3) × 10¹² times the mass of the Sun
🔎 What does that include?
This total mass includes:
- ⭐ Stars (~100–400 billion stars)
- ☁️ Gas and dust
- 🕳 Dark matter halo (the dominant component)
Importantly, ~85–90% of the Milky Way’s mass is dark matter, inferred from stellar motions, satellite galaxy dynamics, and halo star kinematics.
🧮 How is it measured?
Astronomers estimate the mass using:
- Motions of globular clusters
- Orbital velocities of satellite galaxies (e.g. the Large Magellanic Cloud)
- Gaia measurements of halo stars from the Gaia mission
- Escape velocity calculations near the Sun
Recent Gaia-based analyses tend to cluster around ~1.1 × 10¹² solar masses as a consensus value.
📏 Size context
The dark matter halo likely extends to a radius of about 200–300 kpc (possibly farther), far beyond the visible disk (~30 kpc radius).