What If the Sun Grew Bigger Every Minute?

#whatif #space #sun #science #astronomy 6:58 in the evening, sunset over the sea, a quiet rooftop. Then the Sun starts to grow. A little, then a little more, and it doesn't stop. The sea steams, palm trees catch fire, metal melts, the ground turns to lava, Mercury and Venus are swallowed, and finally the Sun's surface reaches Earth. The rule: the Sun gets wider but keeps the same surface temperature and the same mass. A wider Sun at the same temperature shines more: twice as wide means four times the sunlight. The panel shows how much wider the Sun is, how much stronger its light is, how wide it looks in your sky, and how hot a dark surface facing it can get. WHAT IS REAL Sunlight takes about 8 minutes 20 seconds to reach Earth, so you would see the change 8 minutes after it started. Today the Sun is about half a degree wide in the sky. Around 10% more sunlight is estimated to be enough, over a long time, for Earth to lose its oceans (the "moist greenhouse" limit). At 1.38 times wider, Earth gets about as much sunlight as Venus (1.9 times ours); at 2.6 times, as much as Mercury (6.7 times). Temperatures are for a dark surface facing the Sun with no cooling: about 230 °C at 1.9x (paper ignites), 327 °C (lead melts) around 2.6x, 660 °C (aluminum) at 6.5x, about 1,200 °C (rock) at 17x and 1,538 °C (iron) at 25x. Mercury orbits at 0.39 AU and Venus at 0.72 AU, so a Sun 83 and 155 times wider reaches their orbits. Earth is 215 Sun-radii away. At 152 times wider the Sun is 90 degrees across and covers almost a third of the sky. In about 5 billion years the Sun will become a red giant, swelling to over 200 times its current width. Whether it will reach Earth is still debated. WHAT IS NOT REAL OR NOT KNOWN Nothing can make the Sun grow like this. In reality heat would spread, the air and oceans would react over hours and days, and the atmosphere would carry heat around the planet; we show simple, immediate surface temperatures. A real red giant is much cooler and redder at its surface than today's Sun. Planets that are swallowed would not vanish instantly. The city and its people are made up.