~700 km
ESTIMATED DIAMETER
15.8 DAYS
ORBITAL PERIOD
~37,000 km
DISTANCE FROM ERIS
2005
DISCOVERED
1
KNOWN MOON OF ERIS
ERIS
PARENT BODY
THE MOON OF ERIS
Dysnomia is the only known natural
satellite of the dwarf planet Eris.
It was discovered in 2005, shortly
after Eris itself was identified.
The moon is much smaller than Eris
and orbits the dwarf planet at a
distance of roughly 37,000 kilometres.
Its orbit takes approximately
15.8 Earth days.
Dysnomia is extremely distant from
the Sun, making detailed observations
of its surface very difficult.
Scientists use observations of
Dysnomia's orbit to determine the
mass of Eris. This makes the moon
particularly important for studying
the Eris system.
DYSNOMIA FEATURES
ONLY MOON
Dysnomia is currently the only
known natural satellite orbiting
the dwarf planet Eris.
DISTANT WORLD
The Eris system lies billions of
kilometres from the Sun in the
distant Kuiper Belt region.
MEASURING ERIS
Dysnomia's orbit allows astronomers
to calculate the mass of Eris with
high precision.
DID YOU KNOW?
Without Dysnomia's orbit,
astronomers would have much more
difficulty determining the mass of
Eris.
WHY DYSNOMIA IS IMPORTANT
Dysnomia is the only known moon of Eris. Its orbital motion is especially valuable because applying orbital mechanics to the Eris–Dysnomia system allows astronomers to determine the system's mass much more directly than observations of Eris alone.
Combining mass with estimates of Eris's size gives information about its bulk density and therefore clues to its internal composition.
ORBONIX · DWARF PLANETS
DYSNOMIA · ERIS SYSTEM
DYSNOMIA · ERIS SYSTEM