Mercury is getting smaller
planet Mercury (solarsystem.nasa.gov)
Scientists have long known that the planet Mercury is shrinking over billions of years. Despite being the world closest to the Sun, its interior has cooled due to leaking internal heat. This means that the rocks and metals in them must experience a slight reduction in volume.
According to the Nature Geoscience paper, Mercury’s shrinking interior means its surface area (crust) is decreasing. This was responded to by developing thrust faultswhere one piece of land is pushed into a nearby area.
This phenomenon is like the wrinkles that form on an apple as it ages. It’s just that the apple shrinks because it dries up, while Mercury shrinks because of thermal contraction in its interior.
The first evidence of Mercury’s shrinking occurred in 1974 when the Mariner 10 mission transmitted images of steep slopes several kilometers high (like escarpments), winding for hundreds of kilometers across the region.
From these observations, it can be concluded that the geological faults are gently dipping, approaching the surface beneath each escarpment and are a response to Mercury’s receding by about 7 km, writes David Rothery, professor of Planetary Geosciences, The Open University.
Also read: These 5 rare phenomena only exist on the planet Mercury, they are special!
A commonly used way to determine the age of Mercury’s surface is to calculate the density of impact craters. The older the surface, the more craters there are. However, this method is complicated because the impact of the crater was much larger in the past.
The consensus view is that most of Mercury’s slopes are about 3 billion years old. But it is not known for certain whether they are all that old. It is possible that the fault under each steep slope only moves once, according to The Conversation website.
When did this happen?
Mercury earthquake
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The largest earthquakes on Mercury may be smaller than natural events on Earth. To accumulate a scarp on Mercury totaling 2-3 km, it would take hundreds of magnitude 9 earthquakes or perhaps millions of smaller events, which could occur over billions of years.
It is important to know the scale and duration of fault movement on Mercury because scientists do not think that Mercury’s thermal contraction will be completely complete, although the time period may slow down.
Until now, there is still little evidence of cracks. But the team found signs that many escarpments have continued to move geologically in recent times, even though this happened billions of years ago.
Also read: 5 problems if Earth had the size and character of Mercury
2023-10-12 22:01:00
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