gps

A dark matter ring around Earth?

Al recente meeting della American Geophysical Union (AGU), un esperto di telecomunicazioni e satelliti GPS dell’Università del Texas, Ben Harris, ha annunciato che una serie di misure effettuate per determinare la massa della Terra, utilizzando i dati GPS, danno sorprendentemente un valore superiore rispetto a quello attualmente accettato dalla International Astronomical Union (IAU). Secondo lo scienziato, questa differenza potrebbe essere dovuta alla presenza di un disco di materia scura all’altezza dell’equatore che circonda il nostro pianeta.

Dark matter is of course the mysterious stuff that physicists have come to believe exists all throughout the Universe. We can’t see it, but researchers have managed to sense its presence in a variety of ways (such as measuring its gravitational impact on stars, other planets, etc.). In so doing, most in the field have come to believe that it makes up approximately 80 percent of all matter. Unfortunately (mainly because it doesn’t appear to absorb or emit light or electromagnetic radiation) none of the studies done so far have been able to prove that dark matter truly exists, thus, the search goes on for some new kind of method to prove that dark matter isn’t just a theory, or alternatively, for some other explanation of what has been observed.

Among other studies, back in 2009, it was noted that space probes passing by Earth experienced unexplainable slight changes in velocity, which some have attributed to them encountering dark matter.

It could not be proven of course, but then there weren’t any other explanations for it either. In this new effort, Harris collected data from several satellite groups (European Galileo, U.S., GPS, GLONASS and Russian), which he then used to measure the mass of the Earth, a process which he describes as calculating by “feeling” the pull on each satellite. In so doing, he reports that his calculations were between 0.005 and 0.008 percent greater than that described by the IAU. The difference, he said, could be explained by a very large disc of dark matter over the equator. Harris’s theory doesn’t take into account changes in orbits of satellites that occur because of relativity, or the impact of gravity from the Sun and moon, thus it’s still very preliminary. If other studies confirm what he’s found however, there exists the possibility that satellites could one day be used to not only prove the existence of dark matter, but to measure it in a very accurate way.

BUT: it seems to be a very preliminary bit of research announced by at a meeting of the American Geophysical Union, with no reviewed or published paper from its investigator. Even the story points out that Harris’ calculation is incomplete. Harris has yet to account for perturbations to the satellites’ orbits due to relativity, and the gravitational pull of the sun and moon. What’s more, preliminary data from NASA’s Juno probe, also presented at the AGU meeting, suggests its speed was as expected as it flew by Earth, casting doubt on the earlier anomalies (see this post).

New Scientist: GPS satellites suggest Earth is heavy with dark matter

New Scientist: Hints of new dark force seen in galactic smash-ups