Question: What is the biggest anmade crater and can be seen from Earth orbit?

Context articles: Geosynchronous orbit
International Space Station
Beta angle
Apollo 8
2006 RH120
Resident Space Object
Soviet space program
Medium Earth orbit
Sedan Crater
Sedan (nuclear test)

A geosynchronous orbit (sometimes abbreviated GSO) is an orbit around Earth of a satellite with an orbital period that matches Earth's rotation on its axis, which takes one sidereal day (23 hours, 56 minutes, and 4 seconds).
 The synchronization of rotation and orbital period means that, for an observer on Earth's surface, an object in geosynchronous orbit returns to exactly the same position in the sky after a period of one sidereal day.
 Over the course of a day, the object's position in the sky traces out a path, typically in a figure-8 form, whose precise characteristics depend on the orbit's inclination and eccentricity.
 Satellites are typically launched in an eastward direction.
 Those closer to Earth orbit faster than Earth rotates, so from Earth, they appear to move eastward while those that orbit beyond geosynchronous distances appear to move westward.
The International Space Station (ISS) is a space station, or a habitable artificial satellite, in low Earth orbit.
 Its first component launched into orbit in 1998, and the ISS is now the largest human-made body in low Earth orbit and can often be seen with the naked eye from Earth.
 The ISS consists of pressurised modules, external trusses, solar arrays, and other components.
 ISS components have been launched by Russian Proton and Soyuz rockets, and American Space Shuttles.
The beta angle (formula_1) is a measurement that is used most notably in spaceflight.
 The beta angle determines the percentage of time an object such as a spacecraft in low Earth orbit (LEO) spends in direct sunlight, absorbing solar energy.
 Beta angle is defined as the angle between the orbital plane of the spacecraft and the vector to the sun (i.e., which direction the Sun is shining from).
 The beta angle is the smaller angle (there are two angles) between the Sun vector (where the Sun is shining from in the sky) and the plane of the object's orbit.
 Note that the beta angle does not define a unique orbit plane; all satellites in orbit with a given beta angle at a given altitude have the same exposure to the Sun, even though they may be orbiting in completely different planes around the Earth.
 The beta angle varies between +90° and −90°, and the direction the satellite revolves around the body it orbits determines whether the beta angle sign is positive or negative.
 An imaginary observer standing on the Sun defines a beta angle as positive if the satellite in question orbits in a counter clockwise direction and negative if it revolves clockwise.
 The maximum amount of time that a satellite in a normal low Earth orbit mission can spend in the Earth's shadow occurs at a beta angle of zero.
 In such an orbit, the satellite is in sunlight no more than 59% of the time.
Apollo 8, the second human spaceflight mission in the United States Apollo space program, was launched on December 21, 1968, and became the first crewed spacecraft to leave Earth orbit, reach the Earth's Moon, orbit it and return safely to Earth.
 The three-astronaut crew — Commander Frank Borman, Command Module Pilot James Lovell, and Lunar Module Pilot William Anders — became the first humans to: travel beyond low Earth orbit; escape Earth's gravity; see Earth as a whole planet; enter the gravity well of another celestial body (Earth's moon); orbit another celestial body (Earth's moon); directly see the far side of the Moon with their own eyes; witness an Earthrise; escape the gravity of another celestial body (Earth's moon); and re-enter the gravitational well of Earth.
 The 1968 mission, the third flight of the Saturn V rocket and that rocket's first crewed launch, was also the first human spaceflight launch from the Kennedy Space Center, Florida, located adjacent to Cape Canaveral Air Force Station.
2006 RH is a tiny near-Earth asteroid and fast rotator with a diameter of approximately 2–3 meters that ordinarily orbits the Sun but makes close approaches to the Earth–Moon system around every twenty years, when it can temporarily enter Earth orbit through "temporary satellite capture" (TSC).
 Most recently, it was in Earth orbit from September 2006 to June 2007.
 As a consequence of its temporary orbit around the Earth, it is currently the smallest asteroid in the Solar System with a well-known orbit.
A Resident Space Object (RSO) is a natural or artificial object that orbits another body e.g. Sun Orbiting, Earth Orbiting, Mars Orbiting etc.
 It is most often used to reference objects that are Earth orbiting.
 In the case of Earth orbiting the possible orbit classifications for an object are: Low Earth orbit (LEO), Medium Earth orbit (MEO), High Earth orbit (HEO) or Geosynchronous Earth orbit (GEO).
The Soviet space program (Russian: Космическая программа СССР, "Kosmicheskaya programma SSSR") comprised the rocketry and space exploration programs conducted by the former Soviet Union (USSR) from the 1930s until its dissolution in 1991.
 Over its sixty-year history, this primarily classified military program was responsible for a number of pioneering accomplishments in space flight, including the first intercontinental ballistic missile (R-7), first satellite (Sputnik 1), first animal in Earth orbit (the dog Laika on Sputnik 2), first human in space and Earth orbit (cosmonaut Yuri Gagarin on Vostok 1), first woman in space and Earth orbit (cosmonaut Valentina Tereshkova on Vostok 6), first spacewalk (cosmonaut Alexey Leonov on Voskhod 2), first Moon impact ("Luna 2"), first image of the far side of the moon ("Luna 3") and unmanned lunar soft landing ("Luna 9"), first space rover ("Lunokhod 1"), first sample of lunar soil automatically extracted and brought to Earth ("Luna 16"), and first space station (Salyut 1).
 Further notable records included the first interplanetary probes: Venera 1 and Mars 1 to fly by Venus and Mars, respectively, Venera 3 and Mars 2 to impact the respective planet surface, and Venera 7 and Mars 3 to make soft landings on these planets.
Medium Earth orbit (MEO), sometimes called intermediate circular orbit (ICO), is the region of space around the Earth above low Earth orbit (altitude of 2000 km ) and below geostationary orbit (altitude of 35786 km ).
Sedan Crater is the result of the Sedan nuclear test and is located within the Nevada Test Site, 12 mi southwest of Groom Lake, Nevada (Area 51).
 The crater was listed on the National Register of Historic Places on March 21, 1994.
 The crater is a man-made object that can be seen from earth orbit with the unaided eye.
Storax Sedan was a shallow underground nuclear test conducted in Area 10 of Yucca Flat at the Nevada National Security Site on July 6, 1962 as part of Operation Plowshare, a program to investigate the use of nuclear weapons for mining, cratering, and other civilian purposes.
 The radioactive fallout from the test contaminated more US residents than any other nuclear test.
 The Sedan Crater is the largest man-made crater in the United States, and is listed on the National Register of Historic Places.