1.1 Planetary Geology

Select 3 correct facts about terrestrial planets.

The age of the Earth is [blank_start]4500 Ma[blank_end].

Meteorites come from the asteroid belt.

The moon is made up of two areas called the [blank_start]maria[blank_end] and [blank_start]highlands[blank_end]. [blank_start]Maria[blank_end] are the dark areas made of [blank_start]basaltic[blank_end] lava flows, generated by the impacts of [blank_start]meteorites[blank_end]. [blank_start]Highlands[blank_end] are the [blank_start]light[blank_end] coloured areas made of the [blank_start]plagioclase[blank_end]-rich rock [blank_start]anorthosite[blank_end].

What 2 planets does the asteroid belt lie between?

Asteroids = rocky objects that fail to form [blank_start]planets[blank_end] but [blank_start]orbit[blank_end] the sun between [blank_start]Mars[blank_end] and Jupiter. [blank_start]Collisions[blank_end] between asteroids result in fragments falling off and falling to Earth's surface when they get captured by [blank_start]gravity[blank_end] as [blank_start]meteorites[blank_end].

A moon is a natural satellite orbiting a planet.

Space exploration to the moon: First manned landing was in [blank_start]1969[blank_end]. The [blank_start]Apollo[blank_end] mission brought back [blank_start]20[blank_end]kg of rock and soil. The oldest rocks dated back to [blank_start]4400[blank_end] Ma. The moon has a [blank_start]solid[blank_end] crust mantle and core. The surface is made of m[blank_start]aria[blank_end] and [blank_start]highlands[blank_end].

Space exploration to Mars: In 1960's space probes [blank_start]Mariner[blank_end]s 3-7 flew by Mars taking photos. They were able to identify huge [blank_start]volcanoes[blank_end] on Mars including [blank_start]Olympus Mons[blank_end], the largest volcanic structure in the solar system. [blank_start]2005[blank_end] Mars Reconnaissance Orbiter was capable of taking photos to show objects [blank_start]10[blank_end]cm in width. 2007 first spacecraft landed on the [blank_start]surface[blank_end] allowing humans to study geology of Mars. 2015 evidence for presence of [blank_start]water[blank_end] was found.

Space exploration to Venus: Spacecraft have landed on Venus and mapped it using [blank_start]radar[blank_end]. This has given accurate [blank_start]temperature[blank_end] and pressure measurements. Venus has no [blank_start]oceans[blank_end] and is covered by rapidly spinning clouds that trap surface heat making it extremely hot.

Most meteorites come from the [blank_start]asteroid belt[blank_end] but some are thought to come from the Moon. They can be identified as coming from the Moon because they have a similar age and [blank_start]composition[blank_end] as the rock samples brought back from the Moon,

Complete the table detailing the different types of known meteorites.

Evidence for impact craters: Distinctive craters which can be seen on the surface of the Moon. Craters have a [blank_start]circular[blank_end] depression with a [blank_start]rim[blank_end] of broken rock. Earth's surface does not show [blank_start]extensive[blank_end] craters. In [blank_start]Arizona[blank_end] there is a 50000 year old meteor crater.

Why are meteorite craters less extensive on Earth than on the Moon?

The impact of a meteor causes: - Material to be [blank_start]ejected[blank_end] and [blank_start]quartz[blank_end] grains to be violently shocked. - Rock [blank_start]strata[blank_end] to be tilted. - Material at depth to be [blank_start]brecciated[blank_end]. - Ejected material falls back to the surface resulting in an [blank_start]inverted[blank_end] sequence of rock. This is because material closer to the surface is ejected [blank_start]first[blank_end] and falls back to the surface [blank_start]earlier[blank_end].

Volcanic [blank_start]activity[blank_end] can be seen on [blank_start]terrestrial[blank_end] planets as a result of [blank_start]heat[blank_end] from their cores. (except for moons of Jupiter which is thought to be generated by tidal heating) Mars and [blank_start]Venus[blank_end] - huge [blank_start]shield[blank_end] volcanoes and extensive lava flows eg. Olympus Mons on Mars Jupiter - very active volcanoes can be see on Io a [blank_start]moon[blank_end] of Jupiter.

What is radiometric dating?

Radiometric dates are given with tolerances to express a degree of uncertainty.

Radiometric dating can be used to determine the [blank_start]age[blank_end] of an object. 2 values are needed: - The [blank_start]rate[blank_end] at which the isotope decays, (the [blank_start]half-life[blank_end]) - The amount of radioactive [blank_start]isotope[blank_end] that was incorporated into the object when it formed. Radiometric dates are given with [blank_start]tolerances[blank_end] to express a degree of [blank_start]uncertainty[blank_end] as the process is complex.

Stony meteorites are thought to represent the [blank_start]mantle[blank_end] because they contain the same minerals that are found in the Earth's mantle. Metallic meteorites are thought to represent the [blank_start]core[blank_end] as they are made of the same elements as the Earth's core. Carbonaceous chondrites are thought to represent the [blank_start]sun[blank_end] because they have similar composition however they have [blank_start]fewer[blank_end] volatiles.

Characteristic features of terrestrial planets: - [blank_start]Metallic[blank_end] cores - High [blank_start]density[blank_end] due to solid surface - Fixed [blank_start]surface[blank_end] features such as volcanoes visible - Fewer [blank_start]moons[blank_end]

Characteristic features of gas giants: - Predominantly [blank_start]hydrogen[blank_end] atmospheres - All thought to have [blank_start]rocky[blank_end] cores - Lower [blank_start]density[blank_end] because they have no solid surface - Many [blank_start]moons[blank_end] - Large [blank_start]orbits[blank_end]

What 2 elements is the sun made of?

Formation of the solar system: 1. Giant cloud of [blank_start]gas[blank_end] and dust collapsed under [blank_start]gravity[blank_end]. 2. Material formed into a [blank_start]rotating[blank_end] disk called the [blank_start]protoplanetary[blank_end] disk. 3. Gravity drew material towards the [blank_start]centre[blank_end] and heated by friction which triggered nuclear fusion reactions resulting in the formation of the sun. 4. Other planets formed by [blank_start]accretion[blank_end] of material. 5. [blank_start]Less[blank_end] dense material formed the gas giants. 6. Denser material formed the terrestrial planets. 7. Planets began to [blank_start]differentiate[blank_end]. Asteroid belt is made of material that [blank_start]failed[blank_end] to form a planet.

The age of the Universe is approximately [blank_start]13700 Ma[blank_end].

Meteorite = A fragment of [blank_start]rock[blank_end] from [blank_start]space[blank_end] that has [blank_start]fallen to Earth[blank_end].

Describe the likely origin of the Earth's magnetic field: [blank_start]Convection[blank_end] cells OR [blank_start]self-exciting[blank_end] dynamo from moving [blank_start]liquid[blank_end] iron in the [blank_start]outer[blank_end] core.

How is magnetic inclination in rocks used as evidence for continental drift? Magnetic [blank_start]inclination[blank_end] links to [blank_start]latitude[blank_end] of formation. - The inclination of [blank_start]palaeolatitude[blank_end] at the equator is 0° and at poles 90° may change over time on a continent indicating a change in latitude construction of apparent [blank_start]polar wandering curves[blank_end] show when continents separate as the polar wandering curves are [blank_start]different[blank_end].

Formation of palaeomagnetism in rocks: [blank_start]Iron[blank_end] minerals in magma align themselves [blank_start]parallel[blank_end] to the Earth's [blank_start]magnetic[blank_end] field. As the [blank_start]igneous[blank_end] rocks cool below the [blank_start]Curie[blank_end] point, the magnetism is fixed and preserved in the rocks as [blank_start]remanent[blank_end] magnetism.

Put the steps for the formation of the solar system in the right order from 1-7.