Astonomy exam 4

belt–zone circulation

The atmospheric circulation typical of Jovian planets. Dark belts and bright zones encircle the planet parallel to its equator.

irregular satellites

A moon with an orbit that has large eccentricity or high inclination to the equator of its parent planet or is retrograde. Irregular moons are thought to have been captured.

liquid metallic hydrogen

A form of hydrogen under high pressure that is a good electrical conductor.

regular satellites

A moon with an orbit that has small eccentricity, low inclination to the equator of its parent planet, and is prograde. Regular moons are thought to have formed with their respective planets rather than having been captured.

prograde

Rotation or revolution in the direction in common with most such motions in the Solar System. See also retrograde.

oblateness

The flattening of a spherical body, usually caused by rotation.

critical point

The temperature and pressure at which the vapor and liquid phases of a material have the same density.

Io plasma torus

The doughnut-shaped cloud of ionized gas that encloses the orbit of Jupiter’s moon Io.

Tidal heating

The heating of a planet or satellite because of friction caused by tides.

grooved terrain

Region of the surface of Ganymede consisting of bright, parallel grooves.

forward scattering

The optical property of finely divided particles to preferentially direct light in the original direction of the light’s travel.

Io flux tub

A tube of magnetic lines and electric currents connecting Io and Jupiter.

shepherd satellites

A satellite that, by its gravitational field, confines particles to a planetary ring.

gossamer rings

The dimmest part of Jupiter’s ring, produced by dust particles orbiting near small moons.

Roche limit

The minimum distance between a planet and a satellite that holds itself together by its own gravity. If a satellite’s orbit brings it within its planet’s Roche limit, tidal forces will pull the satellite apart.

ovoids

Geological feature on Uranus’s moon Miranda thought to be produced by circulation in the solid icy mantle and crust.

plutinos

One of the icy Kuiper Belt objects that, like Pluto, are caught in a 3:2 orbital resonance with Neptune.

occultation

The passage of a larger body in front of a smaller body.

MKS

meters, kilograms, seconds

biological evolution

The combined effect of variation and natural selection resulting in new species arising and existing species adapting to the environment or becoming extinct. Also called “Darwinian evolution.”

astrobiology

The field of study involving searches for life on other worlds and investigation of possible habitats for such life. Also known as “exobiology.”

mutation

Offspring born with altered DNA.

Miller–Urey experiment

An experiment that reproduced the conditions under which life began on Earth and amino acids and other organic compounds were manufactured.

primordial soup

The rich solution of organic molecules in Earth’s first oceans.

natural selection

The process by which the best traits are passed on, allowing the most able to survive.

DNA (deoxyribonucleic acid)

The long carbon-chain molecule that records information to govern the biological activity of the organism. DNA carries the genetic data passed to offspring.