You live on a lovely terrestrial planet called Earth that conveniently lies in the solar system’s Goldilocks zone or habitable zone. It is just the right distance from the Sun that the planet’s surface doesn’t freeze over, but also isn’t so hot that your bodily fluids would boil.
Of course, you also have the atmosphere. It keeps the Earth warmer than it would have been otherwise. This is due to the greenhouse effect, where short wavelengths of light coming from the Sun are absorbed by the Earth which then release its own long wavelength infrared radiation.
Some of this infrared radiation is trapped by the greenhouse gases in the atmosphere leading to more heating and rising temperatures. So, if it weren’t for the greenhouse gases the temperature on Earth would be below freezing… meaning the life as we know it would not be possible.
So it seems like the Earth is in a pretty good place right now, but what about the future, the way future? In about five billion years, the Sun will run out of hydrogen in its core. When that happens, the Sun will begin to compress under the weight of its gravity while its outer regions expand outward. During all of this, the Sun is losing mass, so its gravitational pull is lessening which means that the Earth’s orbit is able to get larger as if the Earth were retreating away.
But is the larger orbit enough to save life on Earth? Well… no, definitely not. Every billion years, as the Sun burns hydrogen its luminosity or brightness increases about 10%, so within the next billion years or so, this ten percent increase will cause the Earth’s temperatures to rise high enough that the water will begin to evaporate turning your planet into a dry, barren wasteland.
Now, scientists are still unsure whether or not the planet itself will be engulfed by the red giants Sun like the inner planets Mercury and Venus. Some predict that the Earth may be able to avoid being drawn in by the Sun’s gravity but others think a fiery fate is inevitable. So, the only way for life on Earth to continue past that point is to leave the Earth entirely… well before the Sun runs out of hydrogen.