Tolstoj (crater)
Encyclopedia
Tolstoj is a large, ancient impact crater
at latitude −15, longitude 165 on Mercury
. It was named after Leo Tolstoy
. The albedo feature Solitudo Maiae appears to be associated with this crater.
The impact that produced the Tolstoj Basin occurred very early in the history of Mercury. Two ragged, discontinuous rings approximately 356 km and 510 km in diameter encompass the structure but are poorly developed on its north and northeast sides; a third partial ring with a diameter of 466 km occurs on its southeast side. Diffuse patches of material of dark albedo
lie outside the innermost ring. The central part of the basin is covered by a high reflectance smooth plains (HRP) material. The bright interior of the basin is noticeably redder than the surrounding plains, which are made of a bluer low reflectance material (LRM). The dark annulus of ejecta around Tolstoj is one of the darkest places on the surface of Mercury.
The depth of Tolstoj is estimated to be from the stereo
derived digital elevation models based on Mariner 10
images of the planet. This is significantly less than the depth of lunar basins of the similar size indicating that Tolstoj probably has relaxed from its post impact shape. The Tolstoj basin is used to define a time-stratigraphic system, the Tosltojan system, with the age of around 4.0–3.9 billion years. The older system (< 4.0 billion years) is called pre-Tosltojan, while the younger is called Calorian (3.9–3.5 billion years).
Despite Tolstoj’s great age and its embayment by the ancient inter-crater plains, it retains an extensive and remarkably well preserved, radially lineated ejecta
blanket around two-thirds of its circumference. The ejecta tends to be blocky and only weakly lineated between the inner and outer rings. Radial lineations with a slight swirly pattern are best seen on the southwest side of Tolstoj. The unusual rectilinear map pattern of the ejecta suggests: (1) control of the ejecta pattern by prebasin structures, (2) preferential burial along structural trends of an originally symmetrical ejecta blanket by the intercrater plains material, or (3) formation of Tolstoj by an oblique impact from the northwest that produced an ejecta blanket with bilateral symmetry and little or no deposition uprange. Analysis of stereophotography of Tolstoj ejecta northeast of the crater suggests that this deposit has been upwarped to a higher elevation relative to the surrounding plains.
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
at latitude −15, longitude 165 on Mercury
Mercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...
. It was named after Leo Tolstoy
Leo Tolstoy
Lev Nikolayevich Tolstoy was a Russian writer who primarily wrote novels and short stories. Later in life, he also wrote plays and essays. His two most famous works, the novels War and Peace and Anna Karenina, are acknowledged as two of the greatest novels of all time and a pinnacle of realist...
. The albedo feature Solitudo Maiae appears to be associated with this crater.
The impact that produced the Tolstoj Basin occurred very early in the history of Mercury. Two ragged, discontinuous rings approximately 356 km and 510 km in diameter encompass the structure but are poorly developed on its north and northeast sides; a third partial ring with a diameter of 466 km occurs on its southeast side. Diffuse patches of material of dark albedo
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
lie outside the innermost ring. The central part of the basin is covered by a high reflectance smooth plains (HRP) material. The bright interior of the basin is noticeably redder than the surrounding plains, which are made of a bluer low reflectance material (LRM). The dark annulus of ejecta around Tolstoj is one of the darkest places on the surface of Mercury.
The depth of Tolstoj is estimated to be from the stereo
STEREO
STEREO is a solar observation mission. Two nearly identical spacecraft were launched into orbits that cause them to respectively pull farther ahead of and fall gradually behind the Earth...
derived digital elevation models based on Mariner 10
Mariner 10
Mariner 10 was an American robotic space probe launched by NASA on November 3, 1973, to fly by the planets Mercury and Venus. It was launched approximately two years after Mariner 9 and was the last spacecraft in the Mariner program...
images of the planet. This is significantly less than the depth of lunar basins of the similar size indicating that Tolstoj probably has relaxed from its post impact shape. The Tolstoj basin is used to define a time-stratigraphic system, the Tosltojan system, with the age of around 4.0–3.9 billion years. The older system (< 4.0 billion years) is called pre-Tosltojan, while the younger is called Calorian (3.9–3.5 billion years).
Despite Tolstoj’s great age and its embayment by the ancient inter-crater plains, it retains an extensive and remarkably well preserved, radially lineated ejecta
Ejecta
Ejecta can mean:*In volcanology, particles that came out of a volcanic vent, traveled through the air or under water, and fell back on the ground surface or on the ocean floor...
blanket around two-thirds of its circumference. The ejecta tends to be blocky and only weakly lineated between the inner and outer rings. Radial lineations with a slight swirly pattern are best seen on the southwest side of Tolstoj. The unusual rectilinear map pattern of the ejecta suggests: (1) control of the ejecta pattern by prebasin structures, (2) preferential burial along structural trends of an originally symmetrical ejecta blanket by the intercrater plains material, or (3) formation of Tolstoj by an oblique impact from the northwest that produced an ejecta blanket with bilateral symmetry and little or no deposition uprange. Analysis of stereophotography of Tolstoj ejecta northeast of the crater suggests that this deposit has been upwarped to a higher elevation relative to the surrounding plains.