Topic 11 (Exploring The Solar System) Flashcards
What are the two types of planet in our solar system
Terrestrial planets-rock around an iron core
Gaseous giant planets-have liquid interiors and substantial atmospheres of mainly helium and hydrogen
What are the different specifications for objects in our solar system
Planet Dwarf planet (SSSOs): .asteroids .meteoroids .comets
What is a dwarf planet
They have sufficient mass to keep themselves spherical but not enough to sweep their orbits clear of other debris
What is an asteroid
Small regular rocky object between 1000km and 10m in diameter
What is a meteoroid
Like an asteroid a small irregular rocky object but less than 10m in diameter
What is a comet
A comet is a mix of compacted dust rock and ice found mainly in the outer region of the solar system
What is the structure of a comet
Nucleus- the main body of rock ice and dust
Coma- a small aura of gas and dust as it approaches the sun
Tail -as it gets closer to the sun a tail of several million kilometres long develops
What are short period comets
Have an orbital period of less than 200yrs most hug the solar systems plane and are thought to originate in the Kuiper belt where Neptunes gravity may have nudged them into their elliptical solar orbits; a subset of these have orbits of less than 20yrs and do not venture much further from the sun than Jupiter.
What are long period comets
A comet with an orbital period of more than 200yrs, comets originate in the Oort Cloud;they have highly unpredictable orbits, some highly inclined to the solar systems plane and others orbiting in the opposite direction of the planets
What is a comets ion tail
A comets ion tail is a tail that is long predominantly blue it is made of charged ions that have been excited by solar wind, when the ions de-excite they emit fluorescent light
What is a comets dust tail
The dust tail is broader,curved is produced by solar radiation pressure that pushes particles out of the nucleus that reflect sunlight making the tail visible. The curvature is due to individual grains of dust following their own independent solar orbit (having now been freed from the comet)
What are the main theories for the origin of water on earth
.Outgassing of oxygen and hydrogen from primordial volcanoes
.deposited by impacts with comets and or giant asteroids
How are most meteoroids formed
When asteroids collide smaller chunks of rock are produced from the impact
How much is one AU (astronomical unit)
150million km = 1.5 x 10*8 km
What is the origin of the invention of the astronomical unit
On rare occasions mercury or Venus cross the solar disc (called transit). It was known Venus’s observed path (chord) would vary due to parallax
Halley used geometry to show the that the angle between two chords could be calculated from their difference in lengths (found by the difference in time for Venus to cross the lunar disc)
Halley showed that if triangulation was used we could calculate the distance from earth to Venus and then earth to the sun which is one AU
