Eternal night would fall over the planet and Earth will start traveling into interstellar space at 18 miles per second. Within 2 seconds, the full moon reflecting the sun's rays on the dark side of the planet would also go dark.
If the sun disappeared for ONLY ONE SECOND, nobody would notice anything other than no light for a single second. Nothing else. Our orbit would change by less than 1 Km as I've shown.
If the sun vanished, life on Earth would quickly become impossible. The first thing we would notice is that the sky would go dark. The last rays of sunlight would reach Earth about eight minutes after the sun's disappearance, as that is how long it takes for light to travel from the sun to Earth.
Destruction of planets would take place, because of the sudden loss of the sun's gravitational pull. Planets, including Earth, would begin moving away from their usual paths and could collide with other gigantic bodies, leading to their destruction.
Within a few days, however, the temperatures would begin to drop, and any humans left on the planet's surface would die soon after. Within two months, the ocean's surface would freeze over, but it would take another thousand years for our seas to freeze solid.
It is the pull of the Moon's gravity on the Earth that holds our planet in place. Without the Moon stabilising our tilt, it is possible that the Earth's tilt could vary wildly. It would move from no tilt (which means no seasons) to a large tilt (which means extreme weather and even ice ages).
Fortunately, Earth retains heat fairly well, so humans wouldn't freeze instantly. Life would get much more difficult immediately, though. Although no one can know for sure exactly what would happen, scientists estimate that the average global surface temperature would drop below 0º F within a week or so.
Scientists estimate that the Sun will die in around 5 billion years. If the Sun miraculously disappeared, the Earth (and all the other objects in the Solar System) would continue their forward motion in a straight line off into space, instead of following their almost-circular orbits.
Life as we know it probably wouldn't exist. The moon is more than just a pretty face to gaze upon at night. It helps direct our ocean currents and tides, the movement of Earth's atmosphere and climate, and even the tilt of our planet's axis.
Eventually, the fuel of the sun - hydrogen - will run out. When this happens, the sun will begin to die. But don't worry, this should not happen for about 5 billion years. After the hydrogen runs out, there will be a period of 2-3 billion years whereby the sun will go through the phases of star death.
It is unlikely, though, that an adult could die directly and exclusively from prolonged darkness. Most likely a person would become ill and die from a range of chronic diseases caused by lack of sunshine, such as diabetes, high blood pressure, and tuberculosis.
A boon for life
The gravitational pull of the moon moderates Earth's wobble, keeping the climate stable. That's a boon for life. Without it, we could have enormous climate mood swings over billions of years, with different areas getting extraordinarily hot and then plunging into long ice ages.
But even stars have limited lifetimes, and someday our sun will die. You don't need to worry about this solar death anytime soon, though. Like all stars, a churning fusion engine fuels the sun, and it still has a lot of fuel left — about 5 billion years' worth.
This second sun, which was once a companion and helper to our sun, is now gone. During the creation of our solar system, this sun was around to help pull in and bulk up the Oort cloud, but over the course of billions of years, this star slowly drifted away, leaving only one star in our solar system.
Light that's emitted from our host star takes eight minutes and 20 seconds to hit our planet. If the sun suddenly blew up, we actually wouldn't know it happened for — you guessed it — eight minutes, 20 seconds — since even that explosive light show would only be traveling, at maximum, the speed of light.
If earth ceased rotating about its axis but continued revolving around the sun and its axis of rotation maintained the same inclination, the length of a year would remain the same, but a day would last as long as a year.
What would happen if Earth stopped spinning? If the Earth stopped spinning, 6 months of daytime and 6 months of nighttime would be experienced. The side of the Earth facing the Sun will experience fiery summers, while the side facing away from the Sun would face deadly winters.
At the bottom of the plates, around 60 miles (100 kilometers) deep, the temperature is about 2,400 degrees Fahrenheit (1,300 degrees Celsius). By the time you get to the boundary between the mantle and the outer core, which is 1,800 miles (2,900 kilometers) down, the temperature is nearly 5,000 F (2,700 C).
Since Earth is surrounded by the vacuum of outer space, it cannot lose energy through conduction or convection. Instead, the only way the Earth loses energy to space is by electromagnetic radiation.
The core is growing by around one millimetre per year, and at that rate, Earth won't have time to fully cool and solidify before the Sun reaches the end of its life. This will happen in around five billion years' time when it'll expand and potentially engulf the planet we live on.
Before Earth and the Moon, there were proto-Earth and Theia (a roughly Mars-sized planet). The giant-impact model suggests that at some point in Earth's very early history, these two bodies collided.
The political tug-of-war over NASA's mission and budget isn't the only reason people haven't returned to the moon. The moon is also a 4.5-billion-year-old death trap for humans and must not be trifled with or underestimated. Its surface is littered with craters and boulders that threaten safe landings.