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List Of Asteroid Close Approaches To Earth In 2021
Below is the list of asteroids that have come close to Earth in 2021. Timeline of known close approaches less than one lunar distance from Earth A list of known near-Earth asteroid close approaches less than 1 lunar distance () from Earth in 2021. For reference, the radius of Earth is about or 0.0166 lunar distances. Geosynchronous satellites have an orbit with semi-major axis length of or 0.110 lunar distances. Warning times by size This sub-section visualises the warning times of the close approaches listed in the above table, depending on the size of the asteroid. It shows the effectiveness of asteroid warning systems at detecting close approaches in 2021. The sizes of the charts show the relative sizes of the asteroids to scale. For comparison, the approximate size of a person is also shown. This is based the absolute magnitude of each asteroid, an approximate measure of size based on brightness. Absolute magnitude 30 and greater (size of a person ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroids
An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. Of the roughly one million known asteroids the greatest number are located between the orbits of Mars and Jupiter, approximately 2 to 4 AU from the Sun, in the main asteroid belt. Asteroids are generally classified to be of three types: C-type, M-type, and S-type. These were named after and are generally identified with carbonaceous, metallic, and silicaceous compositions, respectively. The size of asteroids varies greatly; the largest, Ceres, is almost across and qualifies as a dwarf planet. The total mass of all the asteroids combined is only 3% that of Earth's Moon. The majority of main belt asteroids follow slightly elliptical, stable orbits, revolving in the same direction as the Earth and taking from three to six years to comple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Near-Earth Objects In 2021
A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). If a NEO's orbit crosses the Earth's orbit, and the object is larger than across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but a small fraction are comets. There are over 30,503 known near-Earth asteroids (NEAs) and over a hundred known short-period near-Earth comets (NECs). A number of solar-orbiting meteoroids were large enough to be tracked in space before striking the Earth. It is now widely accepted that collisions in the past have had a significant role in shaping the geological and biological history of the Earth. Asteroids as small as in diameter can cause significant damage to the local environment and human populations. Larger asteroids penetrate the atmosphere to the surfa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth-crosser Asteroids
An Earth-crosser is a near-Earth asteroid whose orbit crosses that of Earth as observed from the ecliptic pole of Earth's orbit. The known numbered Earth-crossers are listed here. Those Earth-crossers whose semi-major axes are smaller than Earth's are Aten asteroids; the remaining ones are Apollo asteroids. ''(See also the Amor asteroids.)'' An asteroid with an Earth-crossing orbit is not necessarily in danger of colliding with Earth. The orbit of an Earth-crossing asteroid may not even intersect with that of Earth. This apparent contradiction arises because many asteroids have highly inclined orbits, so although they may have a perihelion less than that of Earth, their paths can never cross. An asteroid for which there is some possibility of a collision with Earth at a future date and which is above a certain size is classified as a potentially hazardous asteroid (PHA). Specifically, an asteroid is a PHA if its Earth minimum orbital intersection distance (MOID) is <0.05 [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Asteroid Close Approaches To Earth In 2022
Below is the list of asteroids that have come close to Earth in 2022. Timeline of known close approaches less than one lunar distance from Earth A list of known near-Earth asteroid close approaches less than 1 lunar distance () from Earth in 2022. During 2022 about 124 asteroids passed within 1 LD of Earth. As most asteroids passing within a lunar distance are less than 40 meters in diameter, they generally are not detected until they are within several million km of Earth. For reference, the radius of Earth is about or 0.0166 lunar distances. Geosynchronous satellites have an orbit with semi-major axis length of or 0.110 lunar distances. The first asteroid flyby within 1 LD of Earth in 2022 was asteroid 2021 YK (10–20 meters in diameter), which was observed on 27 December 2021 04:40 UT (when it was about 3.8 million km from Earth) and passed from Earth on 2 January 2022. The largest asteroid to pass within 1 LD of Earth in 2022 was with an estimated diameter of ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Asteroid Close Approaches To Earth In 2020
Below is the list of asteroid close approaches to Earth in 2020. Timeline of known close approaches less than one lunar distance from Earth A list of known near-Earth asteroid close approaches less than 1 lunar distance () from Earth in 2020.For a list of current Earth close approaches seClose ApproachesanNEO Earth Close Approaches/ref> For reference, the radius of Earth is about or 0.0166 lunar distances. Geosynchronous satellites have an orbit with semi-major axis length of or 0.110 lunar distances. A number of known asteroids came closer than this in 2020, notably 2020 CW, 2020 JJ, 2020 QG, and which all approached Earth within 0.05 lunar distances. Two objects have been observed to be temporary satellites of Earth: in February 2020 and 2020 SO in September 2020, albeit the latter has been confirmed to be a rocket booster from the Surveyor 2 mission launched in 1966. Warning times by size This sub-section visualises the warning times of the clos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Asteroid Close Approaches To Earth
This is a list of examples where an asteroid or meteoroid travels close to the Earth. Some are regarded as potentially hazardous objects if they are estimated to be large enough to cause regional devastation. Near-Earth object detection technology began to improve around 1998, so objects being detected as of 2004 could have been missed only a decade earlier due to a lack of dedicated near-Earth astronomical surveys. As sky surveys improve, smaller and smaller asteroids are regularly being discovered. The small near-Earth asteroids , 2014 AA, 2018 LA, 2019 MO and 2022 EB5 are the only five asteroids discovered before impacting into Earth (see asteroid impact prediction). Scientists estimate that several dozen asteroids in the size range fly by Earth at a distance closer than the moon every year, but only a fraction of these are actually detected. Timeline of approaches within one lunar distance The average distance to the Moon (or lunar distance (LD)) is about , which is ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Venus
Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never far from the Sun, either as morning star or evening star. Aside from the Sun and Moon, Venus is the brightest natural object in Earth's sky, capable of casting visible shadows on Earth at dark conditions and being visible to the naked eye in broad daylight. Venus is the second largest terrestrial object of the Solar System. It has a surface gravity slightly lower than on Earth and has a very weak induced magnetosphere. The atmosphere of Venus, mainly consists of carbon dioxide, and is the densest and hottest of the four terrestrial planets at the surface. With an atmospheric pressure at the planet's surface of about 92 times the sea level pressure of Earth and a mean temperature of , the carbon dioxide gas at Venus's surface is in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Observation Arc
In observational astronomy, the observation arc (or arc length) of a Solar System body is the time period between its earliest and latest observations, used for tracing the body's path. It is usually given in days or years. The term is mostly used in the discovery and tracking of asteroids and comets. Arc length has the greatest influence on the accuracy of an orbit. The number and spacing of intermediate observations has a lesser effect. Short arcs A very short arc leaves a high uncertainty parameter. The object might be in one of many different orbits, at many distances from Earth. In some cases, the initial arc was too short to determine if the object was in orbit around the Earth, or orbiting out in the asteroid belt. With a 1-day observation arc, was thought to be a trans-Neptunian dwarf planet, but is now known to be a 1 km main-belt asteroid. With an observation arc of 3 days, was thought to be a Mars-crossing asteroid that could be a threat to Earth, but was later ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2018 AH
2018 AH is a sub-kilometer asteroid, classified as near-Earth object of the Apollo group, approximately in diameter. It was first observed on 4 January 2018, by the Asteroid Terrestrial-impact Last Alert System (ATLAS) on Mauna Loa and quickly followed-up by many other surveys, with precovery observations found from Pan-STARRS and PTF from the day previous. It is the largest known asteroid to pass so close to Earth () since in 1971, and until in 2028, although it was only discovered two days after its closest approach on 2 January 2018, at 04:25 UTC. The Tunguska asteroid was likely of a similar size, if not slightly smaller. Before being recovered on 4 January 2022 11:49 UTC at an Earth distance of 9.8 million km, the asteroid only had an observation arc of 46 days and had not been observed since February 2018. Being a short arc object that had not been observed for years generated an uncertainty that is relatively large. Between 24-31 December 2021 it was only known to mak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4660 Nereus
4660 Nereus, provisional designation 1982 DB, is a small (about ) asteroid. It was discovered by Eleanor F. Helin on 28 February 1982, approximately a month after it passed from Earth. Nereus is potentially an important asteroid with a high albedo. It is an Apollo and Mars-crosser, with an orbit that frequently comes close to Earth, and because of this it is exceptionally accessible to spacecraft. Indeed, because of its small size and close orbit, its delta-V for rendezvous of ~5 km/s is smaller than the Moon's, which is about 6.3 km/s. Nereus makes seven approaches to Earth of less than 5 million km between 1900 and 2100. The closest will be on 14 February 2060, at 1.2 million km. The most recent closest approach was on 11 December 2021, when it was 3.9 million km away. During the 2021 approach, the asteroid peaked around apparent magnitude 12.6, requiring a telescope with around a 100mm objective lens to be visually seen. Its orbital period of 1.82 y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3361 Orpheus
3361 Orpheus (1982 HR) is an Apollo asteroid that was discovered on 24 April 1982 by Carlos Torres at Cerro El Roble Astronomical Station. Its eccentric orbit crosses that of Mars and Earth, and approaches Venus as well. From 1900 to 2100 it passes closer than 30 Gm to Venus 11, Earth 33, and Mars 14 times. It passed by Earth at a distance of about in 1937, 1978, 1982, and 2021 and will again in 2025. 3361 Orpheus is a potentially hazardous asteroid (PHA) because its minimum orbit intersection distance (MOID) is less than and its diameter is greater than 140 meters. The Earth-MOID is . With an observation arc of 36 years, the orbit is well-determined for the next several hundred years. The orbital solution includes non-gravitational forces. Missions 3361 Orpheus had been one of the originally proposed targets for the Near Earth Asteroid Rendezvous (NEAR) mission. The proposed AIDA mission's spacecraft, Double Asteroid Redirection Test Double Asteroid Redirec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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