Strange Phenomenon: Why Are Planets 'Running Away' From the Sun Despite Their Extremely Strong Gravitational Force?

The Sun's gravity is one of the key factors that has kept the Solar System stable for billions of years. But something interesting is happening: the planets, including Earth, are constantly moving away from the Sun. This may seem counterintuitive, especially since many people understand gravity to act as a force pulling toward the center.

In fact, the Earth is moving away from the Sun at a rate of about 1.5 cm per year. While this is small and unlikely to have a significant impact in the short term, it still raises the question: why is this happening?

Many people might think that the expansion of the universe is the cause. However, that is not the case. The expansion of the universe – driven by dark energy – only affects regions that are not bound by gravity. The Solar System, with its planets within the Sun's gravitational control, is not affected by this process. The planets are not being 'pushed out' by the expanding universe, but rather by their own dynamics and the way the Sun operates.

Planets, including Earth, are constantly moving away from the Sun.

First, to understand why the planets don't fall straight into the Sun, we need to consider their motion. The planets are not stationary, but move horizontally around the Sun at great speeds. The Earth, for example, is traveling at a speed of up to 107,826 km/h. This speed is the result of the momentum the planets gained during their formation from the protoplanetary disk billions of years ago. It is this horizontal motion that creates circular or elliptical orbits that keep the planets from being pulled into the Sun.

So why are the planets moving away from the Sun instead of maintaining a stable orbit? The answer lies in the Sun itself. Over time, the Sun is losing mass. The process of nuclear fusion in the Sun's core, where hydrogen is converted into helium, continuously releases energy in the form of radiation and particles, gradually reducing the Sun's mass. At the same time, the solar wind —a stream of charged particles that emanates from the Sun's surface—carries a small amount of matter into space. Although this mass loss is very slow, at about 10⁻¹³ solar masses per year, it is still enough to cause gravity to weaken slightly. As gravity weakens, the orbits of the planets gradually widen, causing the planets to move farther and farther away from the Sun.

This doesn't mean , however, that Earth and the other planets will continue to drift away from the Sun forever without any danger. In the distant future, when the Sun reaches the end of its life, the story will change completely. When the Sun runs out of hydrogen in its core, it will enter a red giant phase. The core will collapse, and the temperature and pressure will increase, causing helium to begin fusing into carbon. This process will push the Sun's outer layers away from it, causing it to swell. During this phase, the Sun's outer layers may expand to the point where they will engulf nearby planets like Mercury, Venus, and possibly Earth. But don't worry, this won't happen for at least another 5 billion years.

The planets' drifting away from the Sun is a natural phenomenon, a consequence of the long-term evolution of the Solar System. Although the rate of change is small and insignificant in the short term, it still provides us with important insights into how gravity and dynamics work in space. And while the planets are drifting away, their ultimate fate – especially Earth's – will be tied to how the star itself will change over the next billion years.