If the Sun suddenly went out, Earth would face catastrophic and rapid changes: Immediate Effects (after about 8 minutes):

• We would not notice the Sun's disappearance instantly because sunlight takes about 8 minutes and 20 seconds to reach Earth. After this delay, total darkness would fall as the Sun's light ceases

• Photosynthesis would stop immediately, causing plants to die and disrupting the entire food chain

Within One Week:

• The average surface temperature would drop from about 15°C to freezing (0°C or 32°F), making most of the planet uninhabitable

Within One Year:

• The average temperature would plummet to around -75°C (-103°F). Oceans would begin to freeze from the surface downward, though deep ocean waters might remain liquid for some time due to geothermal heat

• Most surface life would perish due to the cold and lack of food. Humans could only survive in limited geothermal areas for a while

Within Ten Years and Beyond:

• Earth's temperature could drop to around -219°C (-362°F) and continue falling toward absolute zero (-273°C or -459°F). The atmosphere itself would freeze and fall to the ground as snow, and all surface life would be extinct

• Oceans would be completely frozen, and even oxygen would freeze

• Without the Sun’s gravity, Earth would drift away from its orbit, moving in a straight line through space, potentially becoming a rogue planet

Long-Term Outlook:

• Life as we know it would be impossible without the Sun. Only some extremophiles in deep oceans or underground might survive for extended periods using chemical energy instead of sunlight

• Eventually, Earth would become a frozen, lifeless ball drifting through space, with no atmosphere and no sunlight to sustain any form of life

In summary, the Sun going out would lead to immediate darkness, a rapid and severe global temperature drop, collapse of ecosystems, extinction of surface life, and the Earth drifting away into space as a frozen planet