It is inevitable that the sun will eventually run out of fuel and cease to be the fiery ball of hotness we see every day. Don’t worry it won’t happen when any of us are alive. In fact, scientists believe that we still have about 5 to 7 billion more years until this will happen. Once the hydrogen dies out, gravity will then engulf the sun and the remaining hydrogen will let off its remaining heat at which point the sun will expand and eat up the whole Earth. Lee Anne Wilson of Iowa State University explains “Earth will end up in the sun, vaporizing and blending its material with that of the sun…That part of the sun then blows away into space, so one might say Earth is cremated and the ashes are scattered into interstellar space.” Finally, the sun’s temperature will increase allowing for the helium to start burning up and the sun will shift in shape and size.
The icy planets that are farthest away from the sun will for the first time feel the heat from the red giant that was the sun. As the sun reaches the age of roughly 4 billion years old, it will transition to a reddish color do to a lower frequency energy of infrared and visible red light. What this means is that the sun will actually become even brighter then we know it to be today, yet now have a cool surface temperature. The atmosphere will then expand to swallow up the nearest planets of Mercury, Venus and yes the Earth.
So once life on Earth vanishes, is that the end of all life? Maybe not. As of now we don’t know if there is life in the outer reaches of the solar system, but there is promise according to one research paper. The piece was published in the journal Astrobiology by S. Alan Stern, Director of the Southwest Research Institute’s Department of Space Studies in Boulder, Colorado. Stern notes that “planets located 10 to 50 AU will be in the red giant sun’s habitable zone. The habitable zone of a solar system is the region where water can remain in a liquid state.” Planets like Saturn, Uranus, Neptune and Pluto are located in the 10 to 50 AU range along with their moons. These icy moons and the Kuiper Belt Objects however, have different potentials for life expectancy. For example, Neptune’s moon Triton, Pluto’s moon Charon, and the Kuiper Belt Objects will be the greatest grounds for life. The reason for this comes from the make up of their bodies, that of organic chemicals. The heat of the sun, now the red giant, will let off the heat necessary to melt their icy surfaces into forms of liquid, thereby becoming bodies of water.
Is it possible that the nearest planets to the sun could be destroyed before the sun dies out? Yes, but it is a small percentage. While there is little chance of it happening, the results would be absolute destruction. What am I talking about you ask? There is always the slight chance that gravitational pulls of planets on each other can lead to them becoming out of their respective orbits. Studies estimate that there is a 1 to 2% chance that Mercury’ orbit could fall out of place in the next 5 billion years, which may be around the time the sun begins to die off. If Mercury were to fall out of orbit, the whole inner solar system could have a collision occurring between Earth and Mercury or Earth and Mars. If life were to still be around during such an event, life would be completely obliterated. In one of the studies that shows this other side of planetary destruction, Jacques Laskar of the Observatoire de Paris in France, “ran 1001 computer simulations of the solar system over time, each with slightly different starting conditions for the planets based on the range of uncertainties in the observations”. What he found was 1 to 2% of the simulations showed Mercury’s orbit becoming elongated over time due to the gravitational pull of Jupiter. The orbit went to an “eccentricity” of 0.6 or more (an eccentricity of 0 means the orbit is a perfect circle, while 1 is the maximum possible elongation). When that happens Mercury (6% mass) and Mars (11% mass) will collide more easily than let’s say Venus (82% mass), as they are lighter and it would not take much for them to move out of sync.