Impact events

Question 1

Measuring impact events

Answer 1

Torino Scale

Question 2

Impact event definition

Answer 2

An impact event is a collision between two astronomical objects, most importantly between the Earth and so-called
Near Earth Objects (NEOs) such as asteroids

Question 3

NEO’s

Answer 3

Almost all of the Near Earth Objects (NEOs)
that present a hazard to our planet are
residents of the Solar System

Question 4

Where is the main concentration of objects

Answer 4

The greatest concentration of objects is in the
asteroid belt, located roughly between the
orbits of the planets Mars and Jupiter. This
particular asteroid belt is also termed the main
asteroid belt to distinguish it from other less
significant asteroid populations in the Solar
System, such as the Oort cloud, the Kuiper
belt, the Trojan asteroids, and the Hildas

Question 5

ASteriod

Answer 5

rocky or rock/metal celestial object - some astronomers use the term asteroid only for
objects greater than 10 meters in diameter

Question 6

Meteroid

Answer 6

An celestial object less than 10 meters in diameter. Often used when referring to an object
that is on a path toward Earth

Question 7

Meteorite

Answer 7

A meteoroid that actually strikes the Earth’s surface

Question 8

Meteor

Answer 8

lowing fragments of material (asteroids or meteoroids) that burn and glow upon entering the
Earth’s atmosphere. They are commonly known as ‘shooting stars.’ Some meteors may survive their trip
through the atmosphere and become meteorites, but most burn up completely in the atmosphere.

Question 9

Fireballs

Answer 9

very bright meteors

Question 10

Crater

Answer 10

A depression formed by the impact of a meteorite

Question 11

Airbursts

Answer 11

The explosion of an object in the atmosphere. This typically occurs at altitudes of 7-31
miles. Airbursts generate violent shock waves but do not create a crater.

Question 12

Meteorites classification

Answer 12

-stones
-irons
-stony irons

Question 13

Stone classification

Answer 13

Stony meteorites are the most common type. They are mostly composed of silicate minerals, similar to rocks
commonly found on the Earth. Because they resemble common rocks they are often not recognized as meteorites.

Question 14

Irons classification

Answer 14

Iron meteorites are composed of alloys of iron and often nickel.. They have a high density and distinct
appearance, so are much more commonly found. They have a characteristic structure that suggests they formed in the
cooling core or a much larger object that has since broken up

Question 15

Stoney irons classification

Answer 15

Stony iron meteorites consist of a mixture of silicate materials and iron. They may have formed by the
fusing of various materials by large forces or high temperatures

Question 16

Peekskill meteorite

Answer 16

On the evening of October 9, 1992, a fireball was observed by many people across the entire East
Coast. As this was a Friday night, many people were outside at high school football games and
observed (and even videotaped) the event.
The 26 pound (12 kg) meteorite finally struck a 1980 Chevy Malibu owned by 17-year-old Michelle
Knapp of Peekskill, NY. There’s no need to feel bad for Ms. Knapp - she sold the car (which had cost
her only $300) to a meteorite aficionado for $25,000. She was also able to sell the meteorite to a
collector consortium for $50,000. The car and the remains of the meteorite remain popular artifacts
and are often displayed at various events

Question 17

Chelyabinsk (Russia) Airburst

Answer 17

The Chelyabinsk event was caused by a 20 meter (65 feet) diameter object that generated a spectacular fireball and
airburst explosion. The object entered the Earth’s atmosphere over on February 15, 2013.
Due to its high velocity and flat trajectory through the atmosphere, the object exploded in an airburst over Chelyabinsk
at a height of around 30 km (19 miles). The light from the meteor was visible up to 100 km (62 mi) away. The total energy
released is estimated to have been equivalent to 20-30 as much as released from the atomic bomb detonated at
Hiroshima.
For several reasons, the object was undetected before it became a fireball. First, its approach direction caused it to be
initially obscured by the Sun. Also, astronomers attention was focused on another notable (and predicted) close
approach of a very significant asteroid on the exact same day - the roughly 30 m (98 ft) 367943 Duende.
The Chelyabinsk explosion caused considerable panic - many feared it was a military attack. About 1,500 people were
injured seriously enough to seek medical treatment, mainly by flying glass from windows shattered by the intense shock
wave following the explosion.

Question 18

Tunguska (Russia) Event

Answer 18

The Tunguska event was a huge airburst explosion that
occurred near the Tunguska River on June 30, 1908. The
explosion over the (very fortunately) sparsely populated region
of Siberia flattened 770 square miles of wild forest - some 80
million trees.
An object estimated to be about 60 meters (200 feet) entered
the Earth’s atmosphere and exploded/disintegrated at an
altitude of 3 to 6 miles. The Tunguska event is the largest
impact event on Earth in recorded history. The energy of the
airburst explosion may have been as large as 30 megatons of
TNT, or 1,000 times greater than that of the atomic bomb
dropped on Hiroshima, Japan. A 30 megaton explosion of this
magnitude could destroy a large metropolitan area

Question 19

Chicxulub Event

Answer 19

This is an impact crater buried underneath the Yucatán Peninsula in Mexico. The Chicxulub crater is
estimated to be 90 miles in diameter, with depth of as much as 12 miles, possible penetrating the crust
of the Earth.
It was formed by a very large asteroid or comet estimated to have been about seven miles in diameter.
Since the date of the impact coincides precisely with the Cretaceous–Paleogene extinctions (e.g., end
of the dinosaurs) a widely accepted theory is that worldwide climate disruption from the event was the
cause of a mass extinction in which 75% of plant and animal species on Earth became extinct,
including all non-avian dinosaurs.

Question 20

Impact craters characteristics

Answer 20

show distinct shock wave damage deep into the Earth
materials that are compressed and/or melted due to heat and pressure - often creating a rock
composite called breccia
bowl-shaped depressions with upraised rims
an ejecta blanket around the crater often made of powdered rocks
large slabs of over-turned rock

Question 21

Impact scale

Answer 21

This scale has two
parameters - the likelihood
of an impact and the
energy likely to be
released by an impact
(which determines how
much damage is likely). As
of this writing (October
2019), there are no objects
with a Torino score above
0.