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Micrometeoroid
A micrometeoroid is a tiny meteoroid: a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through Earth's atmosphere and reaches Earth's surface. The term "micrometeoroid" was officially deprecated by the IAU in 2017, as redundant to meteoroid. Origins and orbits Micrometeoroids are very small pieces of rock or metal broken off from larger chunks of rock and debris often dating back to the birth of the Solar System. Micrometeoroids are extremely common in space. Tiny particles are a major contributor to space weathering processes. When they hit the surface of the Moon, or any airless body ( Mercury, the asteroids, etc.), the resulting melting and vaporization causes darkening and other optical changes in the regolith. Micrometeoroids have less stable orbits than meteoroids, due to their greater surface area to mass ratio. Micrometeoroids that fall to Earth can provide information on millimeter scale ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteoroid
A meteoroid () is a small rocky or metallic body in outer space. Meteoroids are defined as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide. Objects smaller than this are classified as micrometeoroids or space dust. Most are fragments from comets or asteroids, whereas others are collision impact debris ejected from bodies such as the Moon or Mars. When a meteoroid, comet, or asteroid enters Earth's atmosphere at a speed typically in excess of , aerodynamic heating of that object produces a streak of light, both from the glowing object and the trail of glowing particles that it leaves in its wake. This phenomenon is called a meteor or "shooting star". Meteors typically become visible when they are about 100 km above sea level. A series of many meteors appearing seconds or minutes apart and appearing to originate from the same fixed point in the sky is called a meteor shower. A meteorite is the remains of a meteoroid th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micrometeorites
A micrometeorite is a micrometeoroid that has survived atmospheric entry, entry through the atmosphere of Earth, Earth's atmosphere. Usually found on Earth's surface, micrometeorites differ from meteorites in that they are smaller in size, more abundant, and different in composition. The International Astronomical Union, IAU officially defines meteorites as 30 micrometers to 1 meter; micrometeorites are the small end of the range (~submillimeter). They are a subset of cosmic dust, which also includes the smaller interplanetary dust particles (IDPs). Micrometeorites enter Earth's atmosphere at high velocity, velocities (at least 11 km/s) and undergo heating through drag (physics), atmospheric friction and Compression (physics), compression. Micrometeorites individually weigh between 10−9 and 10−4 g and collectively comprise most of the extraterrestrial material that has come to the present-day Earth. Fred Lawrence Whipple first coined the term "micro-meteorite" to des ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interplanetary Dust Cloud
The interplanetary dust cloud, or zodiacal cloud (as the source of the zodiacal light), consists of cosmic dust (small particles floating in outer space) that pervades the space between planets within planetary systems, such as the Solar System. This system of particles has been studied for many years in order to understand its nature, origin, and relationship to larger bodies. There are several methods to obtain space dust measurement. In the Solar System, the interplanetary dust particles have a role in scattering sunlight and in emitting thermal radiation, which is the most prominent feature of the night sky's radiation, with wavelengths ranging 5–50 μm. The particle sizes of grains characterizing the infrared emission near Earth's orbit typically range 10–100 μm. Microscopic impact craters on lunar rocks returned by the Apollo Program revealed the size distribution of cosmic dust particles bombarding the lunar surface. The ’’Grün’’ distribution of interpl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extraterrestrial Materials
Extraterrestrial material refers to natural objects now on Earth that originated in outer space. Such materials include cosmic dust and meteorites, as well as samples brought to Earth by sample return missions from the Moon, asteroids and comets, as well as solar wind particles. Extraterrestrial materials are of value to science as they preserve the primitive composition of the gas and dust from which the Sun and the Solar System formed. Categories Extraterrestrial material for study on earth can be classified into a few broad categories, namely: # Meteorites too large to vaporize on atmospheric entry but small enough to leave fragments lying on the ground, among which are included likely specimens from the asteroid and Kuiper belts as well as from the moon and from Mars. # Moon rocks brought to Earth by robotic and crewed lunar missions. # Cosmic dust collected on Earth, in the Earth's stratosphere, and in low Earth orbit which likely include particles from the present day i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micrometeorite
A micrometeorite is a micrometeoroid that has survived entry through the Earth's atmosphere. Usually found on Earth's surface, micrometeorites differ from meteorites in that they are smaller in size, more abundant, and different in composition. The IAU officially defines meteorites as 30 micrometers to 1 meter; micrometeorites are the small end of the range (~submillimeter). They are a subset of cosmic dust, which also includes the smaller interplanetary dust particles (IDPs). Micrometeorites enter Earth's atmosphere at high velocities (at least 11 km/s) and undergo heating through atmospheric friction and compression. Micrometeorites individually weigh between 10−9 and 10−4 g and collectively comprise most of the extraterrestrial material that has come to the present-day Earth. Fred Lawrence Whipple first coined the term "micro-meteorite" to describe dust-sized objects that fall to the Earth. Sometimes meteoroids and micrometeoroids entering the Earth's atmospher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interplanetary Dust Cloud
The interplanetary dust cloud, or zodiacal cloud (as the source of the zodiacal light), consists of cosmic dust (small particles floating in outer space) that pervades the space between planets within planetary systems, such as the Solar System. This system of particles has been studied for many years in order to understand its nature, origin, and relationship to larger bodies. There are several methods to obtain space dust measurement. In the Solar System, the interplanetary dust particles have a role in scattering sunlight and in emitting thermal radiation, which is the most prominent feature of the night sky's radiation, with wavelengths ranging 5–50 μm. The particle sizes of grains characterizing the infrared emission near Earth's orbit typically range 10–100 μm. Microscopic impact craters on lunar rocks returned by the Apollo Program revealed the size distribution of cosmic dust particles bombarding the lunar surface. The ’’Grün’’ distribution of interpl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micrometeorite
A micrometeorite is a micrometeoroid that has survived entry through the Earth's atmosphere. Usually found on Earth's surface, micrometeorites differ from meteorites in that they are smaller in size, more abundant, and different in composition. The IAU officially defines meteorites as 30 micrometers to 1 meter; micrometeorites are the small end of the range (~submillimeter). They are a subset of cosmic dust, which also includes the smaller interplanetary dust particles (IDPs). Micrometeorites enter Earth's atmosphere at high velocities (at least 11 km/s) and undergo heating through atmospheric friction and compression. Micrometeorites individually weigh between 10−9 and 10−4 g and collectively comprise most of the extraterrestrial material that has come to the present-day Earth. Fred Lawrence Whipple first coined the term "micro-meteorite" to describe dust-sized objects that fall to the Earth. Sometimes meteoroids and micrometeoroids entering the Earth's atmospher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch beyond one astronomical unit. If sufficiently bright, a comet may be seen from Earth without the aid of a telescope and may subtend an arc of 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures and religions. Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several mill ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harvard Observatory
The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy. It is located in Cambridge, Massachusetts, United States, and was founded in 1839. With the Smithsonian Astrophysical Observatory, it forms part of the Center for Astrophysics Harvard & Smithsonian. HCO houses a collection of approximately 500,000 astronomical plates taken between the mid-1880s and 1989 (with a gap from 1953–1968). This 100-year coverage is a unique resource for studying temporal variations in the universe. The Digital Access to a Sky Century @ Harvard project is digitally scanning and archiving these photographic plates. History In 1839, the Harvard Corporation voted to appoint William Cranch Bond, a prominent Boston clockmaker, as "Astronomical Observer to the University" (at no salary). This marked the founding of the Harvard College Observatory. HCO's first teles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fletcher Watson
Fletcher G. Watson (c. 1912 – 7 May 1997) was an American professor of science education at the Harvard Graduate School of Education (1946–77), where he served as the Henry Lee Shattuck Professor of Education (1966–77). Watson was a founder and co-director of Harvard Project Physics. Early life and education Watson was born in Baltimore, Maryland in 1912. He graduated in astronomy at Pomona College in 1933 and earned a Ph.D. in astronomy in 1938 at Harvard University. Career Following his Ph.D., Watson joined the Harvard College Observatory, researching meteors, meteorites, and solar observation. During World War II, Watson served in the Navy, where he worked on the Long Range Navigation (LORAN) system. He left the navy in 1946 with the rank of lieutenant commander. Harvard University president James Bryant Conant appointed Watson a professor of science education at the Harvard Graduate School of Education, where he served from 1946 until 1977. He was named Harvard's first H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fred Whipple
Fred Lawrence Whipple (November 5, 1906 – August 30, 2004) was an American astronomer, who worked at the Harvard College Observatory for more than 70 years. Amongst his achievements were asteroid and comet discoveries, the " dirty snowball" hypothesis of comets, and the invention of the Whipple shield. Life Whipple was born on November 5, 1906, in Red Oak, Iowa, as the son of a farmer. An early bout with polio ended his ambition of being a professional tennis player. Whipple studied at Occidental College in Southern California, then majored in mathematics at the University of California at Los Angeles, graduating in 1927. Recollecting his path from mathematics to astronomy, Whipple stated in a 1978 autobiography that his "mathematics major veered imthrough physics and finally focused on astronomy where time, space, mathematics, and physics had a common meeting ground." After taking a class in astronomy, he enrolled at the University of California, Berkeley where he obtai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helmut Landsberg
Helmut Erich Landsberg (1906–1985) was a noted and influential climatologist. He was born in Frankfurt, Germany, February 9, 1906 and died December 6, 1985 in Geneva, Switzerland while attending a meeting of the World Meteorological Organization. Landsberg was an important figure in meteorology and atmospheric science in education, public service and administration. He authored several notable works, particularly in the field of particulate matter and its influence on air pollution and human health. He is the first to write in English about the use of statistical analysis in the field of climatology and implemented such statistical analysis in aiding military operations during World War II. He received a number of significant honors during his life. Several honors are now bestowed in his name in recognition of his contributions to his field. Origins and education Landsberg was an only child of a Jewish couple. His father, Georg Landsberg, was a physician and his mother, Cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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