Vulcan and the Mercury Anomaly

Mercury makes its rounds around the Sun a little faster than predicted by Newton, and this has been a subject for debate in astronomy ever since this was discovered. However, the debate is currently considered settled by Einstein, who demonstrated that a curved space-time could account for the observed fact. But this doesn't mean that there are no alternative explanations.

Alternative explanations

I've presented two possible alternatives in my book, and Dr. Robitaille, who's an expert on astrophysics, has come up with an elegant take on the phenomenon that doesn't invoke anything outside of standard Newtonian mechanics.

Dr. Robitaille starts off by mentioning the hypothetical planet Vulcan that was proposed as a first attempt at explaining the anomaly back in the nineteenth century. The idea was that if there was a planet orbiting between Mercury and the Sun, this planet would pull Mercury with it, thereby speeding it up ever so slightly. However, the planet was never found, and the idea was abandoned.

But if the Sun has a blob inside of it so that the center of gravity is a little skewed we'll get the same effect. The blob rotates with the Sun, and whenever it passes Mercury, it gives Mercury a little tug. Vulcan may in other words exist, but as a blob inside our Sun rather than a planet orbiting it.

Jupiter's Red Spot

An interesting aspect of Dr. Robitaille's proposed blob is its similarity to Jupiter's Red Spot, because the Red Spot is in fact a blob. It has been measured to be gravitationally stronger than its surroundings. It stands taller than the surrounding atmosphere, and it's becoming more circular and compact.

However, the Vulcan blob is not visible at the surface of the Sun. If it exists, it's located somewhere below the Sun's surface. But apart from that, the blob and the Red Spot have a lot in common, so if the Red Spot is an embryonic moon of Jupiter, could it be that the Vulcan blob is an embryonic planet that might one day be ejected by the Sun?

Jupiter ejecting a moon