Since the Sun settled onto the Main Sequence after its formation, it has gradually brightened. It is now 30% brighter than it was then.
The brightening is caused by accumulation of helium ash in the Sun's core. This causes the core's equilibrium state to be denser and hotter, with more energy being produced.
In another billion years or so, this will drive the Earth into a runaway greenhouse effect. The oceans will evaporate and the hydrogen will be lost to space. Not long after, the Earth will be a dead planet devoid of any life, even microorganisms. You sometimes see statements about how when the Sun expands into a red giant it will destroy life on Earth, but the Earth will have long been lifeless by that time.
In case others were curious about the term Helium ash:
Ash is the name given to the energetic alpha-particles or helium nuclei produced by fusion reactions in a deuterium-tritium plasma, even though helium bears no physical resemblance to ash from a fire.
The way I read it, it isn't a co2 greenhouse, in fact the death stroke is the increased co2 absorption at those temperatures due to weathering of rock. Driving co2 below what plants can survive. Building a parasol at l1 that can be modulated to vary what is passed and what is harvested will be necessary at some point. It could get a couple extra billion years potentially.
Anyone else question why astronomers are so sure about things that happened 5+ billion years ago ? I guess otherwise there’d be a probably or a maybe in every sentence ? But then how do you tell when they really are sure ?
pfdietz|1 year ago
The brightening is caused by accumulation of helium ash in the Sun's core. This causes the core's equilibrium state to be denser and hotter, with more energy being produced.
In another billion years or so, this will drive the Earth into a runaway greenhouse effect. The oceans will evaporate and the hydrogen will be lost to space. Not long after, the Earth will be a dead planet devoid of any life, even microorganisms. You sometimes see statements about how when the Sun expands into a red giant it will destroy life on Earth, but the Earth will have long been lifeless by that time.
bloopernova|1 year ago
Ash is the name given to the energetic alpha-particles or helium nuclei produced by fusion reactions in a deuterium-tritium plasma, even though helium bears no physical resemblance to ash from a fire.
galangalalgol|1 year ago
naveen99|1 year ago
baxtr|1 year ago
So who is right?
baxtr|1 year ago
rawling|1 year ago
dtech|1 year ago
sampo|1 year ago
Sun has been getting about 8% brighter (8% more energy output) every 1 billion years.
whinvik|1 year ago