Can a star orbit a planet
In: Planetary Science
The problem here is that in order to consider an object to be orbiting another object, the object being orbited must be much more massive than the orbiting object. If we define a star as an object capable of a self sustaining fusion reaction, anything more massive than that would also be a star or some sort of stellar remnant (white dwarf, neutron star, or black hole), not a planet.
Technically, stars and planets orbit each other, so yes. But in the way we commonly define orbit, no.
Take two golf balls and tie them together with a sting of some length. Then throw them up in the air while spinning them. They will rotate around the the middle of the string because their masses are equal. Now replace one of those golf balls with a baseball and throw it up in the air while spinning them. The golf ball is going to look like it is closer to “orbiting” the baseball, but the baseball is still going to move around a little bit. This is because the common center of mass is much closer to the baseball than the golf ball.
The same principal would apply to planets and starts, except the relationship would be closer to a marble and a wrecking ball tied together. There still is SOME pull between them, but it’s so insignificant that we just write it off as nothing.
It seems like you might be wondering if the biggest planet in the observable universe is bigger than the smallest star.
Logic would make us feel that the bigger object is always being orbited by the smaller one (even though it’s both orbiting each other)
So let’s explore.
Even the biggest planet in the observable universe is much smaller than even the smallest star.
Here’s the accurate comparison:
Largest known planet: ROXs 42 Bb with a radius about 1.12 times that of Jupiter (roughly 71,492 km).
Smallest known star: 2MASS J0523-1409 with a radius about 0.15 times that of the Sun (roughly 696,000 km).
As you can see, even though ROXs 42 Bb is quite large for a planet, it’s still more than 6 times smaller than the smallest star. Stars are significantly more massive than planets, leading to their much larger sizes.
So there is no scenario where a planet is bigger than a star looking like the earth and the moon.
In the way you are probably asking, no, it’s not possible. A star has to be a certain mass for the fusion to start, and that is more massive than any planet could be.
As others have pointed out, everything in a system orbits a central point caused by the mass of all objects. So it is possible that if a planet gets dragged into the center point of a binary star system (system with two stars), it would appear that the stars are orbiting the planet, but its still not actually happening.
Technically the Sun and Jupiter are orbiting each other. The Barycenter of Jupiter and the Sun is juuuust out side the Sun.
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