The Earth is not orbiting the Sun, but something else: NASA explains
The key to this updated theory is the "barycenter", which can be defined as the centre of mass of two bodies in the orbiting system.
NASA explained that the Earth is not orbiting the Sun but something else nearby recent discovery has changed the conception of how we look at the obituary motion of the planets in the solar system. Until now, we used to believe that Earth revolves around the sun.
The key to this updated theory is the “barycenter”, which can be defined as the centre of mass of two bodies in the orbiting system, in this case, the Earth and Sun. NASA explained that this point, known as the Barycenter is not fixed in the case of the Sun.
Gravitational Dynamics: Earth and the Sun
The Sun exerts the most dominant gravitational force on the planets because of its massive size. It pulls Earth into its orbit. As per Newton’s law of gravitation, Earth also exerts a gravitational pull on the Sun, although much weaker, which is negligible to the Sun.
This mutual gravitational interaction causes the barycentre to shift slightly. Typically, this point is very close to the Sun’s centre, but it doesn’t always remain within the Sun’s boundaries. The influence of other giant planets like Jupiter and Saturn can pull the barycentre even further from the Sun’s centre.
Therefore, Earth’s orbit can be better described as a path around this shared center of mass, rather than strictly around the Sun itself.
According to NASA, “Kepler’s third law describes the relationship between the masses of two objects mutually revolving around each other and the determination of orbital parameters.”
It further explains “Consider a small star in orbit about a more massive one. Both stars actually revolve about a common center of mass, which is called the barycenter. This is true no matter what the size or mass of each of the objects involved. Measuring a star’s motion about its barycenter with a massive planet is one method that has been used to discover planetary systems associated with distant stars.”
Dr James O’Donoghue, Planetary astronomer explained on X that “Planets orbit the Sun in general terms, but technically they don’t orbit the Sun alone because the gravitational influence of (mainly) Jupiter means planets must orbit a new point in space.”
“The planets do orbit the Sun of course, we are just being pedantic about the situation. The natural thinking is that we orbit the Sun’s centre, but that very rarely happens, i.e. it’s very rare for the solar system’s centre of mass to align with the Sun’s centre,” he added.
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