How It Works

Every 2.4 million years, Mars changes Earth’s seafloor


Mars’ gravitatio­nal pull on Earth may be influencin­g the climate on our planet, new research hints. Geological evidence tracing back more than 65 million years and taken from hundreds of sites across the world suggests that deep-sea currents have repeatedly gone through periods of being either stronger or weaker. This happens every 2.4 million years and is known as an ‘astronomic­al grand cycle.’ The stronger currents, known as ‘giant whirlpools’ or eddies, may reach the seafloor at the deepest parts of the ocean, known as the abyss. These powerful currents then erode away at the large pieces of sediment that accumulate during calmer periods in the cycle.

These cycles happen to coincide with the timing of known gravitatio­nal interactio­ns between Earth and Mars as the two planets orbit the Sun. “The gravity fields of the planets in the Solar System interfere with each other, and this interactio­n, called a resonance, changes planetary eccentrici­ty, a measure of how close to circular their orbits are,” said Dietmar Müller, a professor of geophysics at the University of Sydney. Due to this resonance, Earth is pulled slightly closer to the Sun by Mars’ gravitatio­nal pull, meaning our planet is exposed to more solar radiation and hence has a warmer climate, before drifting backwards again, all over a period of 2.4 million years.

Researcher­s in the new study used satellite data to map the accumulati­on of sediment on the ocean floor over tens of millions of years. They found that there were gaps in the geological records where sediment stopped building up within these astronomic­al cycles. They believe that this could be linked to stronger ocean currents as a result of warmer weather caused by Mars’ gravitatio­nal influence on Earth. These findings support the idea that the Red Planet influences the climate on Earth, just as passing stars and other astronomic­al objects have been theorised to. However, the observed warming effect isn’t linked to global warming that is being driven by human greenhouse gas emissions.

Neverthele­ss, although speculativ­e at this stage, the findings suggest that this cycle may help periodical­ly maintain some of the ocean’s deep currents in the event that global warming decreases them. “We know there are at least two separate mechanisms that contribute to the vigour of deepwater mixing in the oceans,” Müller said. One of these mechanisms is known as Atlantic Meridional Overturnin­g Circulatio­n (AMOC). This acts as an ocean conveyor belt, bringing warm water from the tropics to the Northern Hemisphere and pulling heat deep into the ocean in the process.

 ?? ?? Within cycles of millions of years, Mars pulls Earth closer to the Sun
Within cycles of millions of years, Mars pulls Earth closer to the Sun

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