48P/Johnson
Komety 48P/Johnson (góra) i 129P/Shoemaker-Levy (dół) | |
Odkrywca | |
---|---|
Data odkrycia | 25 sierpnia 1949 |
Nazwy alternatywne | 1949 II; 1956 V; 1963 IV; 1970 IV; 1977 I; 1983 XVIII; 1990 XXIII |
Elementy orbity | |
Półoś wielka | 3,5317 au |
Mimośród | 0,4252 |
Peryhelium | 2,0300 au |
Aphelium | 5,0335 au |
Okres orbitalny | 6,64 lat |
Nachylenie orbity względem ekliptyki | 13,0590° |
Długość węzła wstępującego | 114,9165° |
Argument peryhelium | 210,3703° |
Moment przejścia przez peryhelium | 3 sierpnia 2018 |
Charakterystyka fizyczna jądra | |
Średnica | 5,74 km |
48P/Johnson – kometa krótkookresowa, należąca do rodziny Jowisza.
Odkrycie
Kometa została odkryta 25 sierpnia 1949 roku w Union Observatory w Południowej Afryce przez Ernesta Johnsona.
Orbita komety
Orbita komety 48P/Johnson ma kształt elipsy o mimośrodzie 0,43. Jej peryhelium znajduje się w odległości 2,03 j.a., aphelium zaś 5,03 j.a. od Słońca. Jej okres obiegu wokół Słońca wynosi 6,64 roku, nachylenie orbity do ekliptyki to wartość 13,06˚.
Właściwości fizyczne
Średnica jądra komety 48P/Johnson wynosi 5,7 km.
Zobacz też
Bibliografia
- 48P/Johnson w bazie Jet Propulsion Laboratory (ang.)
- 48P/Johnson w bazie Minor Planet Center (ang.)
Linki zewnętrzne
Media użyte na tej stronie
These images of the Jupiter-family comets Johnson (top) and Shoemaker-Levy 3 (bottom) were both taken with Spitzer's multiband imaging photometer (MIPS) at a wavelength of 24 microns.
The fan-shaped region that stretches upward from Johnson's nucleus (yellow ball in the middle) represents the dust "tail" of the comet. Dust tails are created when small particles from a comet are swept backward by the Sun's radiation pressure.
The image of Shoemaker-Levy 3 (bottom) does not show a dust tail.
In both images the long thin trail of emission that precisely follows the orbit of the comet is believed to be a debris trail of solid material, ranging from millimeters to centimeters in size. Such particles, called meteoroids, are the same size as those that appear in meteor showers when they enter the Earth's atmosphere. Because any trace of water would evaporate in the Sun's heat, astronomers do not believe that debris trails contain ice.
These meteoroids have evaded detection in previous comet images because they are relatively faint in visible light. At mid-infrared wavelengths, meteoroids give off infrared radiation. Any object with an internal temperature higher than absolute zero (-273.5 degrees Celsius or zero Kelvin) produces thermal radiation; objects in the inner solar system give off radiation at mid-infrared wavelengths. Consequently, MIPS allows astronomers to study the production of meteoroids by comets whose orbits do not cross the Earth's path.
Spitzer images have also shown that there is more mass in the debris trails of comets than in their dust tails and gases.
The results of Spitzer's observations are consistent with those obtained by space probes that encountered comet Halley in 1986. In Halley's case, large particles produced by the comet were not only detected, but caused significant damage to the probes.