2.2 Comets And Meteors Flashcards
What is a comet
A ball of rock and ice that form tails in the course of they orbit around the sun
What’s a comets orbit like
Highly Elliptical
When does a comet develop a tail
As they approach the sun
What is a comet tail like
An ion points in the opposite direction to the sun
A dust tail follows the way the comet is moving - sticks out behind
What are the 2 types of comet
Short period comets
Long period comets
Tell me some stuff about short period comets
originate from the Kuiper belt (30-50 au from sun) beyond Neptune and have a life of less than 200 years
Tell me some things about long period comets
Long period comets originate from Oort Cloud which is about 50,000 au from sun
Life more than 200 years can be millions
What do observations of long period comets indicate
Orbits often highly inclined to the ecliptic
What happens to a comet when is approaches the sun
Temperature rises
Gas and dust form a coma (atmosphere)
At even closer distance 2 tails can be developed
What is an ion tail like?
Faces opposite way to sun
Blue coloured
Consists mainly of carbon monoxide that has been ionised by solar wind
What’s ionise
Convert atom, molecules or a substance into ions
What’s a dust tail
A shorter, broader slightly curved tail
Produced by radiation pressure that pushes particles out of nucleus,
Tail stick out behind direction of motion
How long can tails be
Several millions of kilometres long
What is a meteor
A small body of matter from outer space that enters earths atmosphere becoming incandescent which then looks like a streak of light due to friction
Shooting star
What’s a meteoroid
A small body moving in the solar system taming from micrometres to several metres
Usually orbit at speeds of 40km/s
Where do meteoroids originate from
Dust tails of comets forming meteoroid streams/showers
Meteors with a magnitude of -3 or less are called….
Fireballs
What’s a meteorite
If a meteoroid survives through the atmosphere and lands in the earths surface it’s a meteorite
What 3 categories are meteorites classified into
Stones
Irons
Stony irons
What is the radiant
The point where meteors seem to diverge from this point in the sky even though they are actually travelling parallel
How is a meteor shower named
After the constellation the radiant is found
What is a PHO
Potentially hazardous object
Have orbits that bring them closer to us than 0.05 AU
What’s a near earth object? (NEO)
An object whose trajectory might bring them closer than 0.3 AU
Name some examples of solar system collisions
The moon - covered with impact craters from asteroids
Venus and Uranus rotate backwards and sideways and likely due to a gigantic collision in early solar system history
Barringer crater in Arizona
Tunguska event
What diameter of PHOS pose the biggest threat
1km+ - could cause a catastrophe on global scale
What is the Torino scale?
Used to categorise impact hazards
Like Richter scale for earth quakes, number 0-10, 0-1 likely miss
8,9,10 certain collision, capable of regional or world wide devastation
How do we know the Oort Cloud is for real
We see Kuiper belts in other solar systems so the Oort Cloud could be s continuation of a Kuiper belt
Solar system formation models predict that the formation of the giant planets would have scattered small icy objects into the outer solar system. While some would be given enough energy to completely escape the solar system, others would be scattered out to the hypothetical Oort Cloud.
What’s a mircometeorite
A meteorite that can land to the surface without lighting up- becoming incandescent
If A PHO HIT earth what
Could happen
So much dust and debris would be thrown up into atmosphere there would be no sunlight - lowering temperatures and perhaps extincting life
