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Astronomy notes unit 2

Planets 1

Cassini division - a prominent gap between Saturn’s a and b rings

Kuiper belt -A doughnut-shaped ring of space around the Sun beyond the orbit of Pluto that contains manna frozen comet bodies, some of which are occasionally deflected toward the inner solar system.

Southern highlands - Older, cratered terrain in the Martian southern hemisphere.

Retrograde orbit: The orbit of a moon or satellite around a planet that is in the direction opposite to the planet's rotation.

Retrograde Rotation: The rotation of a planet opposite to its direction of revolution around the Sun.

Jeans instability - The condition under which gravitational forces overcome thermal forces to cause part of an interstellar cloud to collapse and form stars and planets.

Jupiter - Largest and most massive planet of the solar system.

Hydrocarbon -A molecule based on hydrogen and carbon.

Dense core - Any of the regions of interstellar gas clouds that are slightly denser than normal and destined to collapse to form one or a few stars.

Callisto -This farthest of the Galilean moons may also have subsurface liquid water ocean, but if it is there, it is about 100km below the surface.

Stellar wind - A flow of gas ejected from the upper atmosphere of a star.

Fusion -The process by which hydrogen is transformed into helium. One helium nucleus results from four hydrogen nuclei.

Titania -Largest moon of Uranus

Synchronous Rotation - The condition when a moon's rotation rate and revolution rate are equal or when a planet's rotation rate equals its moon's revolution rate.

Protoplanetary Disk - A disk of material encircling a protostar or newborn star. Accretion: The gradual accumulation of matter by an astronomical body, usually caused by gravity

Uranus - The first planet discovered in historic times.

Mercury - The innermost and smallest planet of the solar system.

Dwarf Planet - A celestial body that is in orbit around the Sun and has sufficient mass for its self-gravity to pull itself into a nearly spherical shape but does not have enough gravity to clear its orbital neighborhood of all the small debris orbiting there.

Valles marineris - The most impressive canyon system on Mars, and the one of the biggest in the Solar System.

Liquid metallic Hydrogen - A metal-like form of hydrogen that is produced under extreme pressure.

Venus -Second out from the Sun, this planet is perpetually shrouded in clouds.

Shepherd Moon- A small satellite whose gravitational tug is responsible for maintaining a defined ring of matter around a planet such a Saturn or

Curiosity -A car-sized robotic rover currently exploring Gale Crater on Mars.

Solar nebula -The cloud of gas and dust from which the Sun and the rest of the solar system formed.

Accretion - The gradual accumulation of matter by an astronomical body, usually caused by gravity.

Protosun -The Sun prior to the time when hydrogen fusion began in its core.

Planet - A celestial body that is in orbit around a star and has sufficient mass for its self-gravity to pull itself into a nearly spherical shape, and also has enough gravity to clear its orbital neighborhood.

Solar system - The Sun, planets, their satellites, asteroids, comets, and all other objects that orbit the Sun.

Opportunity Rover - A small robotic rover active on Mars since early 2004. Total distance travelled since landing is about 22 miles.

Supernova - A stellar explosion that is more energetic than a nova. It is either due to the collapse of the core of a massive star, or the result of runaway nuclear fusion of a degenerate white dwarf.

Nice model - A theory that describes the formation of the planets and other objects orbiting the Sun, with Jupiter and the other giant planets forming first, followed by the inner planets, asteroid belt, and Oort comet cloud.

Saturn - Often known as the ringed planet, though it is not the only planet of the solar system with rings.

Ringlet - Any one of numerous, closely spaced, thin bands of particles in planetary ring systems.

Mars -The red planet; has two pitifully small moons.

Snow Line - The distance from the Sun beyond which Ices stayed frozen in the early solar system.

Prograde Orbit - An orbit of a moon or a satellite around a planet that is in the same direction as the planet's rotation.

TNO - Trans-Neptunian object: An object orbiting the Sun beyond the orbit of Neptune.

Late Heavy bombardment - A hypothetical result of the outer planet sending a hailstorm of debris into the inner solar system about 4 billion years ago. I would account for the cratering of the Moon and Mercury.

Accretion - The gradual accumulation of matter by an astronomical body is usually caused by gravity.

Big bang - An explosion that took place roughly 15 billion years ago creating all space, time, matter, and energy in which the universe emerged.

Galilean Moons - Any one of the four large moons of Jupiter (lo, Europa, Ganymede, Callisto) that is visible from Earth through a small telescope.

Neptune - The outermost planet of the solar system. its discovery was predicted.

Earth -The only place in the entire Universe where life is known to

Moons - natural satellites: bodies that orbit larger objects, which in turn orbit stars

B ring: the brightest of the three rings of Saturn visible from earth; it lies just inside the Cassini division

Metals - all the elements except for hydrogen and helium

Europa - slightly smaller than earths moon, it has a possible subsurface saltwater ocean that makes it one of the candidates for extraterrestrial life exploration. One of the Galilean moons of Jupiter

Star - sphere of plasma held together by its own gravity. The nearest of these is the sun.

Planets 2

Mantle -That portion of a terrestrial planet located between its crust and core.

Mare basalt - Dark, solidified lava that covers the lunar maria.

Southern Lights (Aurora australis) - Light radiated atoms and ions in Earth's upper atmosphere due to high-energy particles the Sun and seen mostly southern polar regions.

Mesosphere - The layer of Earth's atmosphere above the stratosphere.

Ionosphere - Region of Earth's atmosphere, above the mesosphere, in which sunlight ionizes many atoms.

Great Red spot - A large, red-orange oval-shaped storm in Jupiter's southern hemisphere.

Roche Limit - The shortest distance from a planet or other object at which a second object can be held together by its own gravitational force.

Zones - Light colored bands in Jupiter's cloud cover.

Van Allen radiation Belts - Two flattened, doughnut-shaped regions around Earth where many charged particles (mostly protons and electrons) are trapped by Earth's magnetic field.

Venera 9 lander - Landed on the surface of Venus in 1975.lt lasted 53 minutes on the surface, during which time it sent back the first images from the surface of another planet.

Collision Ejection Theory: The theory that the Moon was created by the impact of a planet-sized object with Earth; presently considered the sot plausible theory of the Moon's formation.

Olympus Mons: Tallest mountain on mars, and the tallest in the Solar System.

Seafloor Spreading: The process whereby magma upwelling along rifts in the ocean floor causes adjacent segments of Earth's crust to separate.

Belts - Dark reddish bands on Jupiter's cloud cover.

Northern vastness (or Northern Lowland): Relatively young, crater-free terrain in the northern hemisphere of Mars

Plate tectonics - The motions of large segments (plates) of Earth's surface caused by convective motions in the underlying mantle.

Hydrogen - The most abundant element in the universe.

Co creation Theory: The theory that the Moon formed simultaneously with Earth and in orbit around it.

Titan - The largest moon of Saturn. It is the only moon known to have a dense atmosphere (mostly Nitrogen). It is larger than the planet Mercury.

Carbon - A major constituent of amino acids (-COOH carboxylic acid end), and what makes organic compounds "organic".

Spring Tide: The greatest daily difference between high tide and low tide occurring when the Moon is new or full.

Stratosphere - The second layer in the Earth's atmosphere, directly above the troposphere.

Continental drift: The gradual movement of the continents over the surface of Earth due to plate tectonics.

Mare - Latin for "sea," a large, relatively crater-free plain on the Moon.

Differential Rotation: The rotation of a nonrigid object in which parts at different latitudes or different gavial distances move at different speeds.

Ozone - the triple oxygen molecule – O3

Elements of life: Oxygen, Nitrogen, Hydrogen, Carbon. OSY is included for producing the amino acids and the genetic instruction molecules DNA and RNA are the elements Sulfur and Phosphorus.

Troposphere - The lowest level of Earth's atmosphere.

Mascon’s - Regions of high-density matter near the surface of the Moon.

Coronal mass Ejection: Large volumes of high energy gas released from the Sun's corona.

Impact breccias - a rock consisting of barrios fragments cemented together by the impact of a meteoroid.

Phobos - The larger and closer of the two moons of Mars

Oxygen - Expelled by plants and the reason for breathing for most animals.

Triton - Largest moon of Neptune, likely an object captured after the planet formed.

Deimos - The smaller and farther of the two moons of Mars

Seismograph - A device used to record and measure seismic waves, such as those produced by earthquakes.

Ozone layer - The lower stratosphere, where most of the ozone in the air exists.

Regolith - The powdery, lifeless material on the surface of a moon or planet. Mare Basalt: Dark, solidified lava that covers the lunar maria.

Mariner 10 spacecraft: Revealed that mercury has a highly cratered surface that gives it a moonlike appearance.

A ring - The outermost ring of Saturn visible from Earth; it is located just beyond the Cassini division.

Planetary differentiation - The process early in the life of each planet whereby denser elements sank inward and lighter ones rose.

Io - Innermost of the Galilean moons of Jupiter. With over 400 active volcanoes, it is the most geologically active object in the Solar System.

Anorthosite - A light-colored rock found throughout the lunar highlands and in some very old mountains on Earth.

Northern Lights (Aurora borealis): Light radiated by atoms and ions in Earth's upper atmosphere due to high-energy particles from the Sun and seen mostly in the northern polar regions.

Crust - The solid surface layer of some astronomical bodies, including the terrestrial planets, the moons, the asteroids, and some stellar remnants.

Scarp - A cliff on Mercury believed to have formed when the planet Cooled and shrank.

Carbon dioxide - major constituent, along with water vapor, of Earth's early atmosphere. CO2 is a greenhouse gas produced in burning hydrocarbons and expelled by animals and is a nutrient source for plants.

Dynamo Theory: The generation of a magnetic field by circulating electric charges.

Ganymede - The largest satellite of Jupiter, and if we don't count the atmosphere of Titan, the largest moon in the Solar System. It is larger than the planet Mercury.

Nitrogen - The major gas in Earth's atmosphere, a major constituent of amino acids (building blocks of proteins (the' "amine" end is -NH2).

Capture Theory: The idea that the Moon was created at a different location in the solar system and subsequently captured by Earth's gravity.

Seismic Waves: Vibrations traveling through or around an astronomical body usually associated with earthquake-like phenomena.

Enceladus: Sixth largest moon of Saturn may contain liquid water - the stuff of life.

Neap Tide: The least change from high to low tide during a day; it occurs during the first- and third-quarter phases of the Moon.