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.
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.