National Aeronautics and Space Administration Logo
Follow this link to skip to the main content NASA Banner
Solar System Exploration
Planets
Leda: Overview
   Back to Jupiter   Overview   Facts & Figures   News 
No Image Available Tag
Contact us if you have an image of this moon.
With a mean radius of 10 km (assuming an albedo of 0.04), Leda is the smallest moon in the Himalia group, a family of Jovian satellites which have similar orbits and appearance, and are therefore thought to have a common origin.

Leda may be a chunk of an asteroid (a C- or D-class asteroid, judging by the fact that it reflects only about 4% of the light it receives), which was broken apart in a collision either before or after being captured by Jupiter's gravity. In this scenario, the other pieces became the other moons in the Himalia group: Himalia (the largest), Lysithea and Elara. A fifth moon, called S/2000 J11, only about 2 km in radius, was considered a candidate for this group. However, it was lost before its orbit could be definitively determined. It may have crashed into Himalia, reuniting two pieces of the former asteroid, and perhaps creating a faint temporary ring of Jupiter near the orbit of Himalia.

At a distance of about 11.2 million km from Jupiter, Leda takes nearly 241 Earth days to complete one orbit.

Discovery:
Leda was discovered on 14 September 1974 by Charles Thomas Kowal on plates taken from 11 through 13 September 1974 with the 122-cm Schmidt telescope at Mount Palomar.

How Leda Got its Name:
Leda was named for a woman in Greek mythology. According to one legend, she was seduced by Zeus (the Greek equivalent of the Roman god, Jupiter), who had taken the form of a swan. This pairing was depicted by a number of artists, including Leonardo da Vinci and Michelangelo. In this story, she bore Zeus two children: Pollux and Helen.

However, in another account, Helen was the offspring of Zeus (in the form of a swan) and Nemesis (in the form of a goose). According to this legend, Nemesis laid an egg following her encounter with Zeus, which a shepherd brought to Leda. Helen hatched out of the egg, and Leda raised her as her own daughter.

The moon's discoverer, Charles T. Kowal, opposed the naming of the satellite, siding with a number of astronomers of the time who preferred the old numbering system. He suggested "Leda" if names were nevertheless to be assigned.

A name ending in "a" was chosen in keeping with the International Astronomical Union's policy for designating Jupiter's outer moons which have prograde orbits (orbiting in the same direction as Jupiter's rotation).

Just the Facts
Orbit Size (semi-major axis):  11,165,000 km
Mean Radius:  10.0 (assuming an albedo of 0.04) km
Volume:  4,189 km3
Mass:  10,940,279,561,609,500 kg
Resources
Headlines
Awards and Recognition   Solar System Exploration Roadmap   Contact Us   Site Map   Print This Page
NASA Official: Kristen Erickson
Advisory: Dr. James Green, Director of Planetary Science
Outreach Manager: Alice Wessen
Curator/Editor: Phil Davis
Science Writer: Autumn Burdick
Producer: Greg Baerg
Webmaster: David Martin
> NASA Science Mission Directorate
> Budgets, Strategic Plans and Accountability Reports
> Equal Employment Opportunity Data
   Posted Pursuant to the No Fear Act
> Information-Dissemination Policies and Inventories
> Freedom of Information Act
> Privacy Policy & Important Notices
> Inspector General Hotline
> Office of the Inspector General
> NASA Communications Policy
> USA.gov
> ExpectMore.gov
> NASA Advisory Council
> Open Government at NASA
Last Updated: 25 Apr 2012