Gas torus
Encyclopedia
A gas torus is a toroidal
cloud of gas or plasma
that encircles a planet. In the Solar System
, gas tori tend to be produced by the interaction of a satellite's atmosphere
with the magnetic field
of a planet. The most famous example of this is the Io plasma torus, which is produced by the ionization of roughly 1 ton per second of oxygen and sulfur from the tenuous atmosphere of Jupiter's
volcanic moon, Io
. Other examples include the largely neutral torus of oxygen and hydrogen produced by Saturn's
moon, Enceladus
, and the proposed (though not observationally supported) torus of nitrogen
produced by Saturn's moon, Titan
.
A notable use of a gas torus in fiction is as the setting for Larry Niven
's novels The Integral Trees
and The Smoke Ring, in which a gas giant
in orbit around a neutron star
generates a gas torus of sufficient density to allow life (including humans) to survive in it. This arrangement is not particularly plausible in the real world, however.
Torus
In geometry, a torus is a surface of revolution generated by revolving a circle in three dimensional space about an axis coplanar with the circle...
cloud of gas or plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
that encircles a planet. In the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
, gas tori tend to be produced by the interaction of a satellite's atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...
with the magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
of a planet. The most famous example of this is the Io plasma torus, which is produced by the ionization of roughly 1 ton per second of oxygen and sulfur from the tenuous atmosphere of Jupiter's
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
volcanic moon, Io
Io (moon)
Io ) is the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of , the fourth-largest moon in the Solar System. It was named after the mythological character of Io, a priestess of Hera who became one of the lovers of Zeus....
. Other examples include the largely neutral torus of oxygen and hydrogen produced by Saturn's
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...
moon, Enceladus
Enceladus (moon)
Enceladus is the sixth-largest of the moons of Saturn. It was discovered in 1789 by William Herschel. Until the two Voyager spacecraft passed near it in the early 1980s very little was known about this small moon besides the identification of water ice on its surface...
, and the proposed (though not observationally supported) torus of nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
produced by Saturn's moon, Titan
Titan (moon)
Titan , or Saturn VI, is the largest moon of Saturn, the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....
.
A notable use of a gas torus in fiction is as the setting for Larry Niven
Larry Niven
Laurence van Cott Niven / ˈlæri ˈnɪvən/ is an American science fiction author. His best-known work is Ringworld , which received Hugo, Locus, Ditmar, and Nebula awards. His work is primarily hard science fiction, using big science concepts and theoretical physics...
's novels The Integral Trees
The Integral Trees
The Integral Trees is a 1984 science fiction novel by Larry Niven . Like much of Niven's work, the story is heavily influenced by the setting: a gas torus, a ring of air around a neutron star...
and The Smoke Ring, in which a gas giant
Gas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...
in orbit around a neutron star
Neutron star
A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...
generates a gas torus of sufficient density to allow life (including humans) to survive in it. This arrangement is not particularly plausible in the real world, however.