|
Lunar Horizon Glow
Lunar horizon glow is a phenomenon in which dust particles in the Atmosphere of the Moon, Moon's thin atmosphere create a glow during lunar sunset. The Surveyor program provided the first data and photos of the phenomenon. Astronauts in lunar orbit observed it during the Apollo 15 and Apollo 17 missions. Cause Dust kicked off from the surface of the Moon will stay in the atmosphere for around 3 hours. Apart from this, electrically charged particles could be levitated by electrostatic fields with a strength of >500 V cm−1. This cloud of dust, near the Terminator (solar), lunar terminator line, forward scatters the light, creating a glow near the horizon during lunar sunset. The dust, 10 micrometers in diameter, is thought to be above 10 km from the lunar surface. The levitation mechanism is thought to eject 107 more particles per unit time into the cloud than those caused by micrometeoroid impacts. The term "Moon fountain" has been used to describe this effect. During ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmosphere Of The Moon
The atmosphere of the Moon is a very sparse layer of gases surrounding the Moon, consisting only of an exosphere. For most practical purposes, the Moon is considered to be surrounded by vacuum. The elevated presence of atomic and molecular particles in its vicinity compared to interplanetary medium, referred to as "lunar atmosphere" for scientific objectives, is negligible in comparison with the gaseous envelopes surrounding Earth and most planets of the Solar System, and comparable to their exospheres. The pressure of this small mass is around , varying throughout the day, and in total mass less than 10 metric tonnes. Otherwise, the Moon is considered not to have an atmosphere because it cannot absorb measurable quantities of radiation, does not appear layered or self-circulating, and requires constant replenishment due to the high rate at which its gases are lost into space. Roger Joseph Boscovich was the first modern astronomer to argue for the lack of atmosphere around the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hal Clement
Harry Clement Stubbs (May 30, 1922 – October 29, 2003), better known by the pen name Hal Clement, was an American people, American science fiction writer and a leader of the hard science fiction subgenre. He also painted astronomically oriented artworks under the name George Richard. In 1998, Clement was inducted into the EMP Museum#Science Fiction and Fantasy Hall of Fame, Science Fiction and Fantasy Hall of Fame. He was named the 17th SFWA Grand Master by the Science Fiction and Fantasy Writers of America in 1999. Biography Harry Clement Stubbs was born in Somerville, Massachusetts, on May 30, 1922. He went to Harvard University, Harvard, graduating with a B.S. in astronomy in 1943. While there he wrote his first published story, "Proof", which appeared in the June 1942 issue of ''Astounding Science Fiction'', edited by John W. Campbell; three more appeared in later 1942 numbers. His further educational background includes an M.Ed. (Boston University 1946) and M.S. in che ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Reconnaissance Orbiter Camera
The Lunar Reconnaissance Orbiter (LRO) is a NASA robotic spacecraft currently orbiting the Moon in an eccentric polar mapping orbit. Data collected by LRO have been described as essential for planning NASA's future human and robotic missions to the Moon. Its detailed mapping program is identifying safe landing sites, locating potential resources on the Moon, characterizing the radiation environment, and demonstrating new technologies. Launched on June 18, 2009, in conjunction with the Lunar Crater Observation and Sensing Satellite (LCROSS), as the vanguard of NASA's Lunar Precursor Robotic Program, LRO was the first United States mission to the Moon in over ten years. LRO and LCROSS were launched as part of the United States's Vision for Space Exploration program. The probe has made a 3-D map of the Moon's surface at 100-meter resolution and 98.2% coverage (excluding polar areas in deep shadow), including 0.5-meter resolution images of Apollo landing sites. The first images fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clementine Observes The Moon, Solar Corona, And Venus (cropped)
A clementine (''Citrus × clementina'') is a tangor, a citrus fruit hybrid between a willowleaf mandarin orange ( ''C.'' × ''deliciosa'') and a sweet orange (''C. × sinensis''), named in honor of Clément Rodier, a French missionary who first discovered and propagated the cultivar in Algeria. The exterior is a deep orange colour with a smooth, glossy appearance. Clementines can be separated into 7 to 14 segments. Similar to tangerines, they tend to be easy to peel. They are typically juicy and sweet, with less acid than oranges. Their oils, like other citrus fruits, contain mostly limonene as well as myrcene, linalool, α-pinene and many complex aromatics. They are sometimes sold under the name Easy-peelers. History The clementine is a spontaneous citrus hybrid that arose in the late 19th century in Misserghin, Algeria, in the garden of the orphanage of the French Missionary Brother Clément Rodier, for whom it would be formally named in 1902. Some sources have attribut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air & Space Smithsonian
''Air & Space/Smithsonian'' was a quarterly magazine published by the National Air and Space Museum in Washington, D.C. Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and federal district of the United States. The city is on the Potomac River, across from Virginia, and shares land borders with ..., United States. Its first publication was in April 1986. Articles in the magazine involve topics related to historical and present aviation and space travel. It also covers military aviation and aeronautical technology. References External links * 1986 establishments in Washington, D.C. Aviation magazines published in the United States Bimonthly magazines published in the United States History magazines published in the United States Magazines established in 1986 Magazines published in Washington, D.C. Smithsonian Institution publications {{hist-mag-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apollo Lunar Surface Experiments Package
The Apollo Lunar Surface Experiments Package (ALSEP) comprised a set of scientific instruments placed by the astronauts at the landing site of each of the five Apollo program, Apollo missions to land on the Moon following Apollo 11 (Apollos Apollo 12, 12, Apollo 14, 14, Apollo 15, 15, Apollo 16, 16, and Apollo 17, 17). Apollo 11 left a smaller package called the Early Apollo Scientific Experiments Package, or EASEP. Background The instrumentation and experiments that would comprise ALSEP were decided in February 1966. Specifically, the experiments, institutions responsible, and principal investigators and coinvestigators were: * Passive Lunar Seismic Experiment: Massachusetts Institute of Technology, Frank Press; Columbia University, George Sutton; Georgia Tech, Robert Hostetler * Lunar Surface Magnetometer: Ames Research Center, C. P. Sonett; Marshall Space Flight Center, Jerry Modisette. * Medium-Energy Solar Wind Spectrometer, Solar Wind: Jet Propulsion Laboratory, C. W. Snyd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Laser Ranging Experiments
Lunar Laser Ranging (LLR) is the practice of measuring the distance between the surfaces of the Earth and the Moon using laser ranging. The distance can be calculated from the round-trip time of laser light pulses travelling at the speed of light, which are reflected back to Earth by the Moon's surface or by one of several retroreflectors installed on the Moon. Three were placed by the United States' Apollo program ( 11, 14, and 15), two by the Soviet Lunokhod 1 and 2 missions, and one by India's Chandrayaan-3 mission. Although it is possible to reflect light or radio waves directly from the Moon's surface (a process known as EME), a much more precise range measurement can be made using retroreflectors, since because of their small size, the temporal spread in the reflected signal is much smaller and because the return will be more evenly reflected with less diffusion. Laser ranging measurements can also be made with retroreflectors installed on Moon-orbiting satellites s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apollo Missions
The Apollo program was a United States human spaceflight program carried out from 1961 to 1972 by the National Aeronautics and Space Administration (NASA), which landed the first astronauts on the Moon. The program used the Saturn IB and Saturn V launch vehicles to lift the Command/Service Module (CSM) and Lunar Module (LM) spacecraft into space, and the Little Joe II rocket to test a launch escape system which was expected to carry the astronauts to safety in the event of a Saturn failure. Uncrewed test flights beginning in 1966 demonstrated the safety of the launch vehicles and spacecraft to carry astronauts, and four crewed flights beginning in October 1968 demonstrated the ability of the spacecraft to carry out a lunar landing mission. Apollo achieved the first crewed lunar landing on the Apollo 11 mission, when Neil Armstrong and Buzz Aldrin landed their LM ''Eagle'' in the Sea of Tranquility and walked on the lunar surface, while Michael Collins remained in lunar orbit i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zodiacal Light
The zodiacal light (also called false dawn when seen before sunrise) is a faint glow of diffuse sunlight scattered by interplanetary dust. Brighter around the Sun, it appears in a particularly dark night sky to extend from the Sun's direction in a roughly triangular shape along the zodiac, and appears with less intensity and visibility along the whole ecliptic as the zodiacal band. Zodiacal light spans the entire sky and contributes to the natural light of a clear and moonless night sky. A related phenomenon is ''gegenschein'' (or ''counterglow''), sunlight backscattered from the interplanetary dust, which appears directly opposite to the Sun as a faint but slightly brighter oval glow. Zodiacal light contributes to the natural light of the sky, though since zodiacal light is very faint, it is often outshone and rendered invisible by moonlight or light pollution. The interplanetary dust in the Solar System forms a thick, pancake-shaped cloud called the zodiacal cloud wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clementine (spacecraft)
''Clementine'' (officially called the Deep Space Program Science Experiment (DSPSE)) was a joint space project between the Ballistic Missile Defense Organization (previously the Strategic Defense Initiative, Strategic Defense Initiative Organization) and NASA, launched on January 25, 1994. Its objective was to test sensors and spacecraft components in long-term exposure to space and to make scientific observations of both the Moon and the near-Earth asteroid 1620 Geographos. Its lunar observations included imaging at various wavelengths in the visible as well as in ultraviolet and infrared, laser ranging Altimeter, altimetry, gravimetry, and charged particle measurements. These observations were for the purposes of obtaining multi-spectral imaging of the entire lunar surface, assessing the surface mineralogy of the Moon, obtaining altimetry from 60°N to 60°S latitude, and obtaining gravity data for the near side. There were also plans to image and determine the size, shape, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star Tracker
A star tracker is an optical device that measures the positions of stars using photocells or a camera. As the positions of many stars have been measured by astronomers to a high degree of accuracy, a star tracker on a satellite or spacecraft may be used to determine the orientation (or attitude) of the spacecraft with respect to the stars. In order to do this, the star tracker must obtain an image of the stars, measure their apparent position in the reference frame of the spacecraft, and identify the stars so their position can be compared with their known absolute position from a star catalog. A star tracker may include a processor to identify stars by comparing the pattern of observed stars with the known pattern of stars in the sky. History In the 1950s and early 1960s, star trackers were an important part of early long-range ballistic missiles and cruise missiles, in the era when inertial navigation systems (INS) were not sufficiently accurate for intercontinental ranges. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crepuscular Ray
Crepuscular rays, sometimes colloquially referred to as god rays, are sunbeams that originate when the Sun appears to be just above or below a layer of clouds, during the twilight period. Crepuscular rays are noticeable when the contrast (vision), contrast between light and dark is most obvious. Crepuscular comes from the Latin word , meaning "twilight". Crepuscular rays usually appear orange because optical path, the path through the atmosphere at dawn and dusk passes through up to 40 times as much air as rays from a high Sun at noon. particulates, Particles in the air light scattering by particles, scatter short-wavelength light (blue and green) through Rayleigh scattering much more strongly than longer-wavelength yellow and red light. Loosely, the term ''crepuscular rays'' is sometimes extended to the general phenomenon of rays of sunlight that appear to converge at a point in the sky, irrespective of time of day. A rare related phenomenon are anticrepuscular rays which can a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
