Ersa (måne)

Ersa
Upptäckt[1]
UpptäckareScott S. Sheppard, M. Devogele, N. Moskovitz, D. J. Tholen. [2]
Upptäcktsdatum2018
Beteckningar
AlternativnamnS/2018 J1, LXXI
Omloppsbana
Periapsis346,7°[3]
Banmedelradie11 483 000 km[3]
Excentricitet0,094[3]
Siderisk omloppstid252,0 dagar[3]
Medelanomali356,6°[3]
Inklination30,61°[3]
Longitud för uppstigande nod93,3°[3]
Måne tillJupiter
Fysikaliska data
Medelradie3 km[3]
Skenbar magnitud+22,9[3]
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Ersa, med de preliminära beteckningarna S/2018 J1 och XLII, är en av Jupiters månar. Den blev först observerad under 2017, men kungörandet dröjde till i juli 2018. Den upptäcktes av en grupp astronomer vid University of Hawaii.[1]

Ersa är cirka 3 kilometer i diameter och roterar kring Jupiter på ett avstånd av cirka 11 483 000 kilometer. Den tillhör Himalia-gruppen bland Jupiters månar.[3]

S/2018 J1 fick efter kungörelsen det officiella namnet Ersa. Ersa är i grekisk mytologi daggens gudinna och dotter till Zeus och Månen.[1]

Referenser

  1. ^ [a b c] ”S/2018 J1” (på engelska). In depth; by the numbers. NASA Science. 29 augusti 2019. https://solarsystem.nasa.gov/moons/jupiter-moons/s-2018-j1/in-depth/. Läst 4 december 2019. 
  2. ^ ”MPEC 2018-O18 : S/2018 J 1” (på engelska). Minor Planet Center. International Astronomical Union (IAU). https://minorplanetcenter.net/mpec/K18/K18O18.html. Läst 4 december 2019. 
  3. ^ [a b c d e f g h i j] Sheppard, Scott S.. ”JupiterMoons” (på engelska). carnegiescience.edu. sites.google.com. https://sites.google.com/carnegiescience.edu/sheppard/moons/jupitermoons. Läst 4 december 2019. 

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The Galilean satellites (the four largest moons of Jupiter).tif

This composite includes the four largest moons of Jupiter which are known as the Galilean satellites. The Galilean satellites were first seen by the Italian astronomer Galileo Galilei in 1610. Shown from left to right in order of increasing distance from Jupiter, Io is closest, followed by Europa, Ganymede, and Callisto.

The order of these satellites from the planet Jupiter helps to explain some of the visible differences among the moons. Io is subject to the strongest tidal stresses from the massive planet. These stresses generate internal heating which is released at the surface and makes Io the most volcanically active body in our solar system. Europa appears to be strongly differentiated with a rock/iron core, an ice layer at its surface, and the potential for local or global zones of water between these layers. Tectonic resurfacing brightens terrain on the less active and partially differentiated moon Ganymede. Callisto, furthest from Jupiter, appears heavily cratered at low resolutions and shows no evidence of internal activity.

North is to the top of this composite picture in which these satellites have all been scaled to a common factor of 10 kilometers (6 miles) per picture element.

The Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft acquired the Io and Ganymede images in June 1996, the Europa images in September 1996, and the Callisto images in November 1997.

Launched in October 1989, the spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment.