Unlike many other planets that “self-heal” through natural geological processes, the surface of Mercury is covered in craters. These are caused by numerous encounters with asteroids and comets.
Most Mercurian craters are named after famous writers and artists. Any crater larger than 250 kilometers in diameter is referred to as a Basin. The Caloris Basin is the largest impact crater on Mercury covering approximately 1,550 km in diameter and was discovered in 1974 by the Mariner 10 probe.
If you observe these two images closely there is one thing common in both images:-yes, the Impact Craters. In the above photos, one is the planet Mercury and the other is the Earth’s moon. The surface of Mercury looks very much like that of the moon, but it is very different in several ways.
This article is going to talk about Mercury craters and see what makes them unique from Earth and Moon’s craters.
What are Craters?
An abrupt circular depression formed by extrusion of volcanic material, by collapse or by the impact of a meteorite is called a crater.
How many craters does Mercury have
Well, Mercury has lots of craters.
This image alone which is only 276 km wide has more than 763 craters. It is impossible to tell exactly how many it has in total since the planet is big (not the biggest but bigger than Earth’s moon at least).
Does it have the most craters
It does. Mercury has more craters than any other planet in the solar system. The only other object which has more craters than Mercury is Callisto (Jupiter’s Galilieon moon).
Why does it have the most craters
It’s not like other planets are not hit by meteoroids it’s that these planets are different from one another. Planets like Venus, Earth, and Mars have an atmosphere so, most of the craters are eroded by wind, rain, volcanic activity, and other forces.
Venus has the fewest craters among the rocky planets because the planet has a very thick atmosphere so most of the craters are burnt in the atmosphere itself.
Thousands of years of erosion have erased most of the craters on Earth so, only the biggest ones remain.
Gas giant planets on the other hand have no solid surface for the meteoroid to impact on.
On Mercury, there is little to no atmosphere so there is no weather to erode those craters. That is why craters that were hit millions of years ago are still visible today.
What caused craters on Mercury
Craters come in two flavors: those that are caused by asteroid and comet impacts and others by volcanic explosions. Most of Mercury’s craters were made early in the evolution of the solar system by meteorites that hit the surface.
How deep are craters
The deepness of the Mercurian craters very widely. Prokofiev is the deepest crater measured on Mercury so far. This crater is located on the north pole of the planet Mercury. It is over 112 Km wide.
The Caloris Basin is the largest impact basin on Mercury. It is about 1,550 km (960 mi) in diameter and is one of the largest impact basins in the solar system.
This crater was formed by the impact of a large meteorite in the early stages of the planet’s formation. To create a crater as large as this one, the impact body must have been at least 100 Km (62 miles) wide.
The crater was discovered in 1974 by Mariner 10.
Inside the crater lies mountains which are up to 2 km (1.2 mi) high.
What do craters tell us
The density of craters on the surface of a planet can be used to indicate the relative age of different places on the surface; the more craters the surface has accumulated, the older the surface. By counting craters on different areas of Mercury’s surface, a relative geologic history of the planet can be constructed, indicating which surfaces formed first and which formed later.
This also explains why Mercury has more secondary craters than the Earth’s Moon.
What are secondary craters?
Secondary craters are the craters formed due to the impact of the ejected material, while primary craters are formed directly by asteroid or comet impact.
Since Mercury’s surface gravity is more than twice that of the Moon, the higher gravity tends to keep the ejected material from traveling as far- only 65 percent of the distance that would be reached on the Moon. So, most of the ejected material falls back on the surface causing the secondary craters.
In the case of the Moon, since gravity isn’t strong enough much of the ejected material flies back into space.
Why study impact craters?
Impact craters scientists to study a planet’s geological history- even when the records are buried beneath the surface..
Bach is a multi-ringed impact basin which is about 225 km in diameter. It is named after a famous German music composer Johann Sebastian Bach.
Beethoven is the 11th largest crater in the solar system and third largest on Mercury. This 630 Km crater is named after a German composer Ludwig van Beethoven.
Data from the Mariner 10 probe suggested that it is older than the Caloris basin- the largest crater on Mercury.
The depth of the crater is estimated to be 2.5 ± 0.7 Km.
Beethoven is very different from many Moon craters of similar size.
Firstly, Beethoven is not multi-ringed while most of the Lunar craters of similar size are multi-ringed.
Secondly, Lunar craters are deeper than the estimated 2.5 Km dept of Beethoven.
Cervantes is a 213 Km wide crater on Mercury named after Miguel de Cervantes – a famous Spanish writer.
This crater’s floor is flooded with volcanic smooth plains material. Copland is 208 Km wide and is named after American composer Aaron Copland.
Dostoevskij is 430 Km in diameter and is one of the biggest craters on Mercury. It is named after Russian novelist Fyodor Dostoyevsky.
Goethe is about 317 km in diameter and is named after a German writer, Johann Wolfgang von Goethe.
Goethe is similar to the Caloris basin in structure but smaller.
Haydn is a 251 Km wide crater on Mercury named after Joseph Haydn- a famous Austrian composer.
Homer is 320 Km in diameter and is named after an ancient Greek poet.
Deposits of material in and around this crater suggest the possibility of explosive volcanic eruptions at some point in the planet’s history.
Kunisada is a 241 Km wide crater on Mercury named after Utagawa Kunisada – a Japanese woodblock printmaker.
Michelangelo is a 216 km wide crater on Mercury named after an Italian painter.
Monet is a 203 Km wide crater on Mercury named after Claude Monet- a French painter.
Mozart is 241 Km in diameter and is located very close to the Caloris basin. Mozart is surrounded by secondary craters, formed by the material thrown out during the formation of the main crater.
Rachmaninoff is a peak-ring impact crater discovered by MESSENGER spacecraft. It is one of the youngest craters on Mercury which his estimated to be just over a billion years old.
While Rachmaninoff is 300 Km in diameter it’s center is occupied by a peak ring which is about 130 km in diameter. The surface color inside the peak is different from color outside the crater.
Rachmaninoff is the fourth impact crater on Mercury (after Caloris, Rembrandt, and Raditladi), where extensional tectonic features have been observed.
It is named after Sergei Rachmaninoff – a Russian composer.
Raditladi is a peak ring impact crater with a diameter of 263 km. The crater is less than 1 billion years old, very young compared to other craters. The surface of the Raditladi is relatively smooth.
The crater is named after Leetile Raditladi – a Botswanan poet.
Rembrandt is the second largest crater on Mercury after Calories. It has a diameter of 715 km. The crater was discovered by MESSENGER spacecraft in 2008. Its age is roughly the same as Caloris and is thought to be created during a late heavy bombardment.
It is named after Rembrandt Harmenszoon van Rijn – A Dutch painter.
Sanai is one of the largest craters on Mercury with a diameter of 490 km.
It is named after Sanai – a Persian poet.
Tolstoj is 390 km wide and was discovered by Mariner 10.
It is one of the oldest craters on the planet.
The dept of Tolstoj is estimated to be 2.O ± 0.7 km.
It is named after Leo Tolstoy – a Russian writer.
Valmiki is about 210 km in diameter and is situated Tolstoj and Beethoven.
It is named after Valmiki – an Indian poet.
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