Immediate cessation of fusion
Should the Sun’s core fusion halt abruptly, the existing radiation field would continue to illuminate Earth for roughly ten thousand years, as no immediate change in sunlight occurs.
Gradual contraction and dimming
Following this interval, the Sun would start to contract slowly. During the collapse it would experience a brief brightening, then continue shrinking while relying on gravitational heat for tens of millions of years.
Neutrinos as early indicators
The disappearance of fusion would be instantly reflected in a sharp drop of neutrino emissions, a signal detectable on Earth within about eight minutes.
Final stage: black hole formation
Continued collapse would increase the Sun’s density to the point where it becomes a black hole, a process taking billions of years as outer layers are expelled into space.
Key points
- No immediate effect on Earth after fusion stops.
- Thousands of years of slow shrinking and brief brightening.
- Neutrino flux drops within minutes.
- Eventual outcome is a black hole.