Copyright © Philip M. Parker, INSEAD. Terms of Use.
Definition: Asteroidal |
AsteroidalAdjective1. Of or relating to or resembling ans asteroid. Source: WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved. |
Date "asteroidal" was first used in popular English literature: sometime before 1985. (references) |
"Asteroidal" is a common misspelling or typo for: steroidal. |
(From Wikipedia, the free Encyclopedia)
An asteroid (minor planet or planetoid) is a relatively small "planet-like" object which orbits within a solar system; generally less than 1km in diameter. They are believed to be remnants of the protoplanetary discs; which were not incorporated into planets during the system's formation. Most asteroids will align themselves within an asteroid belt and some have moonss; asteroids (like most celestial objects) tend to have elliptical orbits. "Small" asteroids (generally fragments from collisions) which are approximately boulder-sized or less, are known as "meteoroids". Asteroids composed largely of ice are known as comets. Some asteroids are the remains of old comets that have had most of their ice driven away by close proximitiy to the Sun, leaving behind only the heavier mineral components.
Earth's Solar System
More than 9000 asteroids have been discovered within Earth's solar system. The largest asteroid in Earth's inner solar system is Ceres, with a diameter of 900-1000km. Two other large asteroids are Pallas and Vesta; both have diameters of ~500km.
See also a list of interesting or noteworthy asteroids in our solar system.
The Centaur, Main, Kuiper, and Trojan Belts
A large group of asteroids have orbits between the orbits of Mars and Jupiter, roughly 2 to 4 AU, in a region known as the Main belt. These couldn't form a planet due to the gravitational influence of Jupiter. Jupiter's gravitational influence also results in Kirkwood gaps in the asteroid belt, orbits cleared by orbital resonance.
Another important group are the Trojans; they are in the orbit of Jupiter, on two Lagrangian points. Similar sets of asteriods appear to lie in the trojan points in almost all planetary orbits.
Another group exists within the Kuiper belt. The Kuiper belt is the source of about half of the comets that come to the inner solar system. Some of these are not much smaller than Pluto and Charon -- the largest found so far is Quaoar, thought to be around 1250 km in diameter, the same size as (or even slightly larger than) Charon - and some astronomers expect that we shall one day find some Trans-Neptunian objects bigger than Pluto. The exact classification of these objects is unclear, since they are probably fairly different from the asteroids of the inner solar system.
The Centaurs orbit the Sun, between the orbits of the giant planets. The first of these to be discovered was 2060 Chiron in 1977. These are generally supposed to be asteroids or comets that were ejected from their original orbits.
Asteroid Discovery
Until 1998, asteroids were discovered by a four-step process. First, a region of the sky was photographed by a wide-field telescope. Pairs of photographs were taken, typically one hour apart. Multiple pairs may be taken over a series of days. Second, the two films of the same region were viewed under a stereoscope. Any body in orbit around the sun would move slightly between the pair of films. Under the stereoscope, the image of the body would appear to float slightly above the background of stars. Third, once a moving body was identified, its location would be measured precisely using a digitizing microscope. The location would be measured relative to known star locations.
These first three steps do not constitute asteroid discovery: the observer has only found an apparition. The final step of discovery was to send the locations and time of observations to Brian Marsden of the Minor Planets Center. Dr. Marsden has computer programs that compute whether an apparition tied together previous apparitions into a single orbit. If so, then the observer of the final apparition is declared a discoverer, and the discoverer got the honor of naming the asteroid (subject to the approval of the International Astronomical Union).
Since 1998, a large majority of the asteroids have been discovered with automated systems that comprise CCD cameras and computers directly connected to telescopes. A list of teams using such automated systems include[1]:
The LINEAR system alone has discovered 157,920 asteroids as of April, 2002 [1]. Between all of the automated systems, 2298 near-Earth asteroids have been discovered [1].
- The Lincoln Near-Earth Asteroid Research (LINEAR) team
- The Near-Earth Asteroid Tracking team
- Spacewatch
- The Lowell Observatory Near-Earth Object Search team
- The Catalina Sky Survey
- The Japanese Spaceguard Association
- The Asiago DLR Asteroid Survey
Asteroid Deflection
There is increasing interest in identifying asteroids whose orbit crosses the Earth's, and that could, given enough time, collide with the earth. The two most important groups of near-Earth asteroids are the Amors, and the Atens. Various asteroid deflection strategies have been proposed.
Asteroid Exploration
The first "nearby" photos, of an asteroid, were taken by the Galileo spacecraft of Gaspra and Ida (1991), while NEAR Shoemaker landed on Eros(2001).
When the orbit of an asteroid is confirmed, it is given a number, and later it may also be given a name (e.g. 1 Ceres). The first few are named after figures from Graeco-Roman mythology, but as such names started to run out, others were also used - famous people, the names of the discover's wives, even television characters. A few groups have names with a common theme - for instance Centaurs are all named after legendary Centaurs, and Trojans after heroes from the Trojan War. The Centaurs are of special interest; many of them are massive comets, such as Chiron.
Asteroid Classification
Asteroids are classified into spectral types by their optical spectrum, which corresponds to the composition of the asteroid's surface material. Note that the proportion of known asteroids falling into the various spectral types does not necessarily reflect the proportion of all asteroids that are of that type; some types are easier to detect than others, biasing the totals.
There are also a number of rarer asteroid types, the number of types continuing to grow as more asteroids are studied.
- C-type asteroids - 75% of known asteroids. The C stands for "carbonaceous." They are extremely dark (albedo 0.03), similar to carbonaceous chondrite meteorites. These asteroids have approximately the same chemical composition as the Sun, minus hydrogen, helium and other volatiles. The spectra of these asteroids have relatively blue colors and are fairly flat and featureless.
- S-type asteroids - This type of asteroids represents about 17% of known asteroids. The S stands for silicaceous. They are relatively bright objects (albedo .10-.22). They have a metallic composition (mainly nickel, iron and magnesium-silicates). The spectra of this class are reddish and similar to those of stony-iron meteorites.
- M-type asteroids - This class includes most of the rest of the asteroids. The M stands for metallic; they are bright asteroids (albedo .10-.18), made of pure nickel-iron.
For general information about a specific asteroid, a table of large and/or noteworthy asteroids in this solar system can be found here.
- E-type asteroids - The E stands for enstatite.
- R-type asteroids - The R stands for red.
- V-type asteroids - The V stands for Vesta, a large asteroid these are thought to be fragments of.
This picture of Eros, taken on February 14, 2000, shows the view looking from one end of the asteroid across the gouge on its underside and toward the opposite end. In this mosaic, constructed from two images taken after the NEAR spacecraft was inserted into orbit, features as small as 120 feet (35 meters) across can be seen. House-sized boulders are present in several places; one lies on the edge of the giant crater separating the two ends of the asteroid. A bright patch is visible on the asteroid in the top left-hand part of this image, and shallow troughs can be see just below this patch. The troughs run parallel to the asteroid's long dimension. Click on the image to see an enlarged version. 
External Links
The Solar SystemSun - Mercury - Venus - Earth - Mars - Asteroids - Jupiter - Saturn - Uranus - Neptune - Pluto - Comets - Kuiper belt - Oort cloud
Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Asteroid."
| Hyphenated Usage | |
Beginning with "asteroidal": asteroidal-sized. | |
| Source: compiled by the editor from various references; see credits. | |
| Language | Translations for "asteroidal"; alternative meanings/domain in parentheses. | |
German | sternartig (asteroid). (various references) | |
Pig Latin | asteroidalay.(various references) | |
Russian | звездообразный (starlike, star-type, stellate, stellated, stellular). (various references) | |
| Source: compiled by the editor from various translation references. | ||
| Words rhyming with "asteroidal" (pronounced 'As`ter*oid"al'): Abyssal, Accrual, Accusal, Actinozoal, Adjournal, Albuminoidal, Amenorrhoeal, Anomal, Anthropoidal, Apogeal, Apohyal, Appraisal, Apprizal, Approval, Arachnoidal, Arctogeal, Arousal, Arrival, Avowal, Axal, Balmoral, Banal, Basihyal, Beheadal, Bequeathal, Bestowal, Betrayal, Betrothal, Burghal, Carousal, Catarrhal, Cemental, Ceratohyal, Choroidal, Cital, Coastal, Cockal, Colloidal, Comprisal, Conchoidal, Conoidal, Convival, CORAL, Coralloidal, Cordal, Cotidal, Crinoidal, Croupal, Crustal, Cryal. (additional references) |
Scrabble® Enable2K-Verified Anagrams | |
| Words within the letters "a-a-d-e-i-l-o-r-s-t" | |
-1 letter: estradiol, idolaters, steroidal. | |
-2 letters: airdates, asteroid, darioles, dataries, delators, diastole, diastral, dilaters, dilators, idolater, isolated, lardiest, lariated, leotards, loadstar, lodestar, radiates, redtails, salaried, sodalite, stolider, tailored. | |
-3 letters: aerials, aerosat, airdate, alastor, areolas, aridest, aristae, asteria, astride, atresia, dariole, dartles, delator, derails, details, dialers, diaster, dilater, dilates, dilator, disrate, editors, estriol, iodates, isolate, isolead. | |
| Words containing the letters "a-a-d-e-i-l-o-r-s-t" | |
+1 letter: desalinator. | |
+2 letters: advertorials, bardolatries, declarations, desalinators, labradorites, rationalised. | |
+3 letters: adorabilities, adulterations, deflagrations, maladroitness, melodramatics, melodramatise, melodramatist, radiationless, revalidations, roadabilities, sacerdotalism, sacerdotalist. | |
+4 letters: degranulations, derealizations, dissertational, melodramatised, melodramatises, melodramatists, melodramatizes, particleboards, sacerdotalisms, sacerdotalists, valedictorians. | |
+5 letters: adrenalectomies, affordabilities, allotetraploids, autotetraploids, demonstrational, demoralizations, depolarizations, desacralization, deuteranomalies, dictatorialness, federalizations, maladroitnesses, melodramatising, predevaluations, proletarianised, radiotelegraphs, tatterdemalions, traditionalizes, undervaluations. | |
| Source: compiled by the editor from various references; see credits. SCRABBLE® is a registered trademark. All intellectual property rights in and to the game are owned in the U.S.A and Canada by Hasbro Inc., and throughout the rest of the world by J.W. Spear & Sons Limited of Maidenhead, Berkshire, England, a subsidiary of Mattel Inc. Mattel and Spear are not affiliated with Hasbro. | |
| 1. Definition 2. Expressions 3. Translations: Modern 4. Rhymes | 5. Anagrams 6. Bibliography |
Copyright © Philip M. Parker, INSEAD. Terms of Use.
