Updated

Updated · spacedaily.com · Jul 13

Sunlight Takes 10,000 to 170,000 Years to Escape the Sun, Then 8 Minutes to Reach Earth

Updated

Updated · spacedaily.com · Jul 13

Sunlight Takes 10,000 to 170,000 Years to Escape the Sun, Then 8 Minutes to Reach Earth

Q: If the Sun’s core engine stopped today, what would be the first sign of trouble visible from Earth?

The first detectable sign from Earth would be a sudden drop in solar neutrinos about eight minutes after the shutdown, not any visible dimming of the Sun. That is because neutrinos are produced directly in the Sun’s fusion reactions and escape the core almost immediately, passing through the Sun and across space at nearly light speed. Observatories such as Super-Kamiokande and SNO-style detectors are designed to monitor that flux, so they would register the change within minutes. By contrast, the Sun’s visible light would look normal for a very long time. The energy now leaving the Sun’s surface was generated in the core tens of thousands of years ago and has been slowly working its way outward through the dense radiative zone by a random walk, then through the convective zone. That huge thermal buffer means the photosphere would keep shining essentially unchanged for thousands of years, and possibly much longer in terms of the Sun’s overall thermal adjustment. So if “visible from Earth” means visible to the human eye, there would be no immediate sign at all. The Sun would continue to appear normal. The earliest warning available to scientists would come from neutrino detectors, roughly eight minutes after the core stopped fusing.

3 articles · Updated · spacedaily.com · Jul 13

NASA says the energy in sunlight spends roughly 10,000 to 170,000 years moving through the Sun’s interior, then just 499 seconds crossing 150 million kilometers to Earth.
In the 15 million-degree core, fusion converts about 600 million tonnes of hydrogen per second, with about 4 million tonnes of mass becoming energy that begins as gamma-ray photons.
Those photons advance only about a millimeter between absorptions and re-emissions, creating a random walk through the radiative zone that can require around 10^22 scattering events before energy nears the surface.
By the photosphere, the original gamma-ray energy has been redistributed into visible, infrared and ultraviolet light, while the outer convective zone carries it upward in weeks or months rather than millennia.
Neutrino detectors and helioseismology support this model, and the long delay helps explain why the Sun shines steadily and why sunlight reveals ancient fusion, not the core’s current state.

Sources

spacedaily.com16h ago

Photon's 10,000-Year Journey Through Sun's Interior Before 8-Minute Trip to Earth

threads.com16h ago

Light can travel for billions of years, yet along its path, zero time passes. But does that mean a photon experiences everything instantly? The real answer is far stranger. Watch our latest

Facebook16h ago

The sunlight warming your skin right now may have begun its journey tens of thousands of years ago, back when mammoths still roamed the Earth. The last leg took only eight minutes,

How did a solar neutrino mystery force a rewrite of the fundamental laws of physics?

Can a new space-based detector finally provide a live feed from the Sun's nuclear furnace?

If the Sun’s core engine stopped today, what would be the first sign of trouble visible from Earth?

The Ancient Light We See: Tracing Sunlight’s Million-Year Path from Solar Core to Earth in 8 Minutes

Overview

Sunlight’s journey to Earth is much longer than its final 8-minute dash across space. Deep inside the Sun’s core, energy is first created as high-energy X-rays. These photons cannot escape directly; instead, they are absorbed and re-emitted countless times, gradually losing energy and transforming into visible light. This process takes millions of years as the energy slowly moves outward through the Sun’s dense layers. Only when a photon finally leaves the Sun’s surface does it travel swiftly to Earth, bringing with it energy that began its journey long ago. This epic voyage connects us to the ancient heart of our star.

...