Life Without The Sun

By: Madeline Claytor

It's no exaggeration to say the sun sustains life here on Earth -- it provides not only light and warmth but also the energy that helps keep us supplied with oxygen and food. But what if the sun exploded or suddenly went cold -- or simply blinked out of existence?

Look on the bright side

The first big change we'd notice would be the absence of light. Of course, this wouldn't happen instantaneously -- it takes eight minutes and 20 seconds for sunlight to reach Earth. But once there's no more sunlight, would we be able to see?

"The Milky Way contributes about as much light as 1/300th of a full moon," Stevens says in the video. "So there would be enough light from space for us to see around a bit, but of course electricity and fossil fuels will still be usable for a while. So cities and towns could continue to be lit by man made sources, just like a typical night, except it would be night everywhere." Without sunlight, photosynthesis would cease. After all, photosynthesis is how plants and some organisms use sunlight to make food from carbon dioxide and water.

"This is huge, 99.9 percent of the natural productivity on Earth is done by photosynthesis, which requires the sun," Stevens says. "Without the sun, plants would no longer be able to inhale carbon dioxide and exhale life-sustaining oxygen."

Bunndle Up

And without sunlight, the Earth would get very, very cold. Earth's surface temperature now averages about 57 degrees Fahrenheit, but by the end of the first week without the sun, the average surface temperature would be below the freezing point.

The planet's ocean surfaces would freeze over, but deep below some liquid water could remain, along with life on the deep sea floor. Stevens says, "The Earth would be a spaceship for these little earthlings basically." One last thing to consider: The sun not only illuminates and heats our planet but also provides the gravitation that keeps us in orbit. So, as Popular Science explains: "If its mass suddenly disappeared (this is equally impossible, by the way), the planet would fly off, like a ball swung on a string and suddenly let go."

Within a day

Within a day temperatures would immediately begin to drop and photosynthesis would stop entirely. The absence of light and freezing weather conditions would not be immediate factors though. As light from the Sun takes eight and a half minutes to reach us, we’d have a final few moments of glorious sunshine before our planet was bathed in darkness. Those on the night side wouldn’t notice much difference until, a few seconds after day-dwellers were thrust into darkness, the Moon suddenly disappeared as it no longer had the Sun’s light to reflect. The planets in the sky would follow suit, disappearing one by one as the wave of darkness reached them. Within days the world would be a hundred or so degrees below freezing, and within weeks it’d be just 50 or so degrees above absolute zero. The atmosphere itself would also freeze and fall to Earth, leaving us exposed to the harsh radiation traveling through space.

Within a week

Within a week, the average global surface temperature would drop below 0°F. In a year, it would dip to –100°. The top layers of the oceans would freeze over, but in an apocalyptic irony, that ice would insulate the deep water below and prevent the oceans from freezing solid for hundreds of thousands of years. Millions of years after that, our planet would reach a stable –400°, the temperature at which the heat radiating from the planet's core would equal the heat that the Earth radiates into space, explains David Stevenson, a professor of planetary science at the California Institute of Technology.

Within a month

Although some microorganisms living in the Earth's crust would survive, the majority of life would enjoy only a brief post-sun existence. Photosynthesis would halt immediately, and most plants would die in a few weeks. Large trees, however, could survive for several decades, thanks to slow metabolism and substantial sugar stores. With the food chain's bottom tier knocked out, most animals would die off quickly, but scavengers picking over the dead remains could last until the cold killed them.

Within a year

Within a year, the average global surface temperature could dip well below -100º F! By that time, the top layers of the oceans of the world would have frozen over. The atmosphere would have also frozen and fallen to Earth, leaving anyone left alive exposed to the harsh cosmic radiation that travels through space.