Flashcards in Lecture #10 -Meteorite Impacts Deck (34):
How was the solar system formed?
Cloud of Gas and dust in space was disturbed by a supernova
4.6 billion years ago
What is Nebular Hypothesis?
The explosion made was in space. This caused the formation of a solar nebula ( a flattened cloud of gas and dust)
What is a super nova?
Explosion of a star
How were the planets formed?
caused from the centre of the solar nebula grew hotter resulting int he formation of the sun
-the edges cooled causing clumps of particles that stick together and form planets
Whats a galaxy?
A cluster of billions of stats
Whats a star?
A hot glowing ball of gas that generates energy by converting H-->He
How long does it take to travel from one side to the other of the galaxy?
What is the temp in the middle of the sun?
15 million Degrees C
What is the photosphere?
Outermost part of the sun
-6000 degrees C
What controls the earths climate system
energy from the sun
What is the order of the 8 planets?
Why is Pluto not a planet?
Because there are a lot of other bolides that circle the solar system, that are the same size of Pluto and we don't consider them planets so we took them out
What happens at the end of a stars lifecycle?
They grow bigger until they explode and massive amounts of energy is released
What is a bolide?
Extraterrestrial bodies that originate in outerspace
What is an Asteroid
A rocky metallic material in space 10-100m in diameter originating in the asteroid belt
What is a Meteoroid?
Smaller objects in space up to 10m in diameter
What is a Meteor?
A meteoroid that has entered earths atmosphere
What is a Meteorite?
A meteor that strikes the earth surface
What is a comet?
These are distinguishable by a glowing tail of gas and dust
What are comets made from?
gas and ice and has a rocky core
-they create the light as gases are released
What is an air burst?
Bolide that travel at velocities of 12-72km/s. They enter the atmosphere and explode at an altitude between 12-50 km above the surface
The Tunguska Airburst
Destroyed a lot of forest in 1908
-no crater was found so it was deemed and air burst
-asteroid was probably ~25-50m
0shockwave produced the airburst
The Chelyabinsk Airburst
Feb 15 2013
Meteor exploded over a city in Russia
1500 people injured due to broken glass
What is an ejecta blanket?
Layers of debris consists of rock fragments that were blow out of the crater on impact
Why arent todays craters as deep?
Because of erosion and weathering over time
50 000 years old located in Arizona
Hole filled in over time due to wind and erosion
Shockwaves blew out the material
What are simple craters?
Less than a few km
Doe not have an uplifted centre
What is a complex crater?
Rim collapses under extreme faulting
Centre flood that rises following impact
greater than 6km
discovered by surface imaging
Formed 35.5 million years ago
didnt overlain with ocean and sediments
Why are craters more common on the moon?
-Most impacts occur in the ocean so no crater is produced
-most have eroded away
-smaller bolides burn up in the atmosphere
Shoemaker Level comet
Entered Jupiters atmosphere in 1994
released massive amounts of energy
-this could happen to us one day too
What is the K-T boundary Mass extinction?
-65 million years ago, an asteroid impacted the earth, ending the dinosaurs
-Found large amounts of Iridium (uncommon on earth but common in space)
-Crater discovered in 1991 in yucatan Peninsula Mexico under sediment and ocean
-asteroid was prob ~10km
Where to asteroids have to stay in order for them not to pose a risk to us?
Mars and Jupiter Asteroid belts