Content tagged "speed of light".
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Sunlight takes about 8 minutes to reach Earth. Light from Proxima Centauri, the nearest star beyond the Sun, takes over four years. Every star you see at night is a snapshot of its past -- and no one can ever see what's happening there right now.
Sunlight left the Sun about eight minutes ago. Light from Proxima Centauri, our nearest star, is about 4.2 years old. The Andromeda Galaxy's light is roughly 2.5 million years old. Because light speed is finite, looking farther always means looking further back in time. SORABUMI translates this into everyday scale to explain why a single glance at the night sky holds hundreds of millions of years at once.