# Do you know how long it takes for sunlight to reach the Earth?

Light from the Sun moves through space’s vacuum at a constant speed and, furthermore, remains unchanged until it reaches the Earth. Have you ever considered how much time it takes to get to us? We explain here.

The speed at which solar light moves through space—i.e., moves in a vacuum—is thought to be constant. It may be stated that it seldom ever changes, and it is because of this remarkable characteristic that the sun’s rays arrive to Earth so quickly. The time it takes for other types of particles, including photons, to exit the solar core is not taken into consideration when scientists estimate that it takes sunlight a few minutes to reach the Earth’s surface. In a similar vein, we must consider the passage of time. Since the Universe demonstrates the existence of galaxies millions of light years from Earth, it is crucial to note that the light emanating from these stars may have left their surfaces millions of years ago. That certainly is a long time.

We need to perform a relatively straightforward calculation to determine how long it takes light from the Sun to reach the Earth: we divide the speed of light in a vacuum (300 000 km/s) by the distance between the Earth and the Sun (150 000 000 km), arriving at a result of 500 seconds, or 8 minutes and 20 seconds. Isn’t that amazing?

The computation is straightforward, the time involved is neither excessively long nor excessively short, but it ignores the time required for photons to leave the solar core. Why are these particles left out of the calculation, then? It’s a little complicated because these particles wander around the star’s interior before leaving and entering space at the star’s surface.

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The photons, which are regarded as elementary particles and are capable of transporting light and all types of radiation, are thought to rove through the Sun’s innards before they arrive at the surface. It should be emphasized that photons come from gamma radiation, which is produced by the sun’s radioactive zone and through multiple cycles of emission and absorption.

This explains why the photons in the Sun take so long to escape the star because they have to travel far. It should be emphasized that the Sun generates these particles by fusing its atoms in a nuclear reaction. The time it takes for photons to leave a star from the time they are produced is an intriguing fact.

The Sun is not the only source of particles known as neutrinos; these subatomic particles can also be found in the core of our planet. They are the full antithesis of photons in that they do not interact with matter and, as a result, are able to travel through the Sun instantly after their formation. This is why they were given this name.

Scientists were able to discover some previously unknown facts about the Sun thanks to the discovery of neutrinos. One of these facts was the speed at which light from the Sun travels to the surface of the Earth. Although the discovery of neutrinos may appear straightforward and uncomplicated, the discovery of these facts was no easy feat. Even taking into account the presence of neutrinos in the Sun, it is conceivable to estimate that it would be a very long time before humans would experience the effects of a solar apocalypse, which can be defined as the complete and utter destruction of the Sun.

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