Earth Is Moving Away From Sun, How It Will Affect Us? What Is Bigger Worry?

The Sun has extremely important influences on our planet: It drives weather, ocean currents, seasons, and climate, and makes plant life possible through photosynthesis. So any changes in the way Sun functions will directly impact the Earth and all the living beings. 

Earth is about 15 crore kilometers from the Sun. However, its orbit is not perfectly circular; it's slightly elliptical, or oval-shaped. This means Earth's distance from the sun can range from about 14.7 crore km to 15.2 crore km.

Sun is steadily losing mass

The nuclear fusion reactions that power the Sun convert mass to energy, according to Einstein's famous equation E = mc^2. As the Sun is constantly producing energy, it's also steadily losing mass. Over the course of the sun's remaining lifetime — estimated at another 5 billion years or so, according to NASA — Sun could lose about 0.1% of its total mass before it begins to die. 

Brian DiGiorgio, an astronomer at the University of California, Santa Cruz said 0.1% may sound like a very small mass but in fact this is a lot of mass. It's about the same amount of mass as Jupiter, which is about 318 times Earth's mass.

Sun's pull on Earth is weakening

The strength of an object's gravitational pull is proportional to how much mass it has. Because the Sun is losing mass, its pull on Earth is weakening, leading our planet to drift away from Sun by about 2.36 inches (6 centimeters) per year, DiGiorgio said. 

Earth's distance from Sun may increase by 0.2%

As the Earth moves away from the Sun, the Sun's light will become dimmer. Earth's distance from the Sun may increase by 0.2% over the next 5 billion years. This dimming corresponds to a 0.4% reduction of solar energy hitting the Earth's surface. This is relatively small compared to the normal variations in the Sun's brightness that happen due to the Earth's elliptical orbit, so it's not much to worry about.

Bigger worry

The bigger thing to worry about is that as the Sun evolves over the next 5 billion years, stellar evolution models predict that it will increase in brightness by about 6% every 1 billion years. As the Sun's brightness will increase, the Earth's temperatures will also rise. Ultimately it will lead to boiling of the oceans. This will render the Earth uninhabitable to humans and other living creatures long before the Sun ever potentially swallows it.