If the sun were to suddenly vanish from Earth's sky, it would have profound and catastrophic consequences immediately. However, the exact time it would take for humanity to realize that the sun had disappeared would depend on several factors:
Speed of Light: The sun is approximately 93 million miles away from Earth. Light travels at a speed of about 186,282 miles per second (299,792 kilometers per second). Therefore, it takes about 8 minutes and 20 seconds for light from the sun to reach Earth. This means that if the sun were to disappear, we would continue to see it in the sky for about 8 minutes and 20 seconds after it actually disappeared.
Observations: Professional and amateur astronomers around the world would likely notice the disappearance of the sun quickly after it occurred. They would observe that the sun's light had suddenly vanished, and it would be a topic of discussion and concern within the scientific community.
Communication: The news of the sun's disappearance would spread rapidly through various communication channels, such as television, radio, internet, and social media. Within minutes to hours, people across the globe would become aware of the event.
Day and Night Cycle: The most noticeable impact on Earth would be the abrupt cessation of daylight. Regions currently experiencing daytime would suddenly plunge into darkness. People in these regions would immediately notice the disappearance of sunlight.
Temperature Changes: The sun's disappearance would lead to a significant drop in temperature on Earth. This drop in temperature would also be noticed quickly, especially in areas with a significant difference between day and night temperatures.
In summary, it would take only a matter of minutes for people on Earth to realize that something drastic had happened, namely the sudden disappearance of the sun. The news of such a catastrophic event would spread worldwide rapidly through various channels of communication, and humanity would face immediate and severe consequences. The long-term implications would be even more dire, as the Earth's ecosystems, climate, and life as we know it would be severely impacted without the sun's energy and light.