Accurate measurements of the orbit of Mercury allowed scientists to calculate how quickly our luminary loses mass, and again to test the general theory of relativity. This is the result of a scientific article published by a scientific group led by Antonio Genova of NASA in the journal Nature Communications.
The sun is losing weight. The reason for this is the solar wind and the transformation of the mass into energy in the course of thermonuclear reactions. However, this process is very difficult to observe, because the luminary on the scales can not be put, and weight loss is also quite slow.
The scientists found a way out by using Mercury as their “agent”. Indeed, the change in the mass of the Sun must inevitably be reflected in the orbit of the planet closest to it.
As the press release of the study explains , the researchers relied on the results of the Messenger device , which worked in the orbit of the planet for five long years from March 2011 to April 2015, and conducted preliminary measurements “on approach” in 2008 and 2009.
Obtained unprecedentedly accurate data on the evolution of the orbit of Mercury for the first time allowed us to distinguish the contribution of changes occurring with the Sun. For this, the team of Genoa had to develop a new mathematical method that would simultaneously calculate the orbits of both the planet and the Messenger.
One such change is the “flattening” of the star: with time its equatorial radius grows, and the polar decreases, as if someone presses the palms on the poles of the sun and deforms it. Another effect is the already mentioned mass loss.
The obtained results are one of the few estimates (and, probably, the most accurate) of the “slimming” of the Sun, obtained through observations, and not just from theory alone. It turned out that the luminary lost a little less than 0.1% of its mass over ten billion years. Accordingly, the change in the orbit of Mercury is measured in centimeters per year.
The orbit of Mercury as an indicator of scientific truth is not news. Once scientists found that the displacement of the nearest to the Sun point of this orbit can not be fully explained by the Newtonian theory of gravitation, if in the solar system there are only known bodies. Astounded astronomers invented the planet Vulcan, which should have been even closer to the Sun and its gravity to disturb the orbit of Mercury.
The reality turned out to be much more interesting. The behavior of the planet was completely explained by the general theory of relativity (GTR). This was the first in the series of her many successes.
This time, scientists again used Mercury to test the GRT, already at a completely different level of accuracy. The test was subjected to a strong equivalence principle, which we recently told about testing with the help of a neutron star and white dwarfs. As expected, Einstein’s theory was once again “on horseback.”
It is very important to check scientific theories with observations and experiments. Accurate and subtle measurements helped researchers to find out whether our ideas about the life of the Sun are correct.
Although the observed rate of “weight loss” turned out to be slightly lower than the calculated ones, on the whole the results are in good agreement with the theory. In the moneybox of mankind there is little more reliable knowledge of the star, to which we owe our existence.
By the way, earlier we wrote about new methods of measuring the mass of stars and their density.
