Chapter 3: Near Earth Objects

Rank the effects of an NEO impact with Earth according to the order in which they would occur as the object approached and impacted Earth. Start with the object entering Earth's atmosphere on the top.

1. The NEO enter's the atmosphere 2.Impacts occurs 3. Thermal radiation is created 4. A very large earthquake occur 5.Ejecta from the crater is shot into the atmosphere 6. Global climate would change

Which of the following processes are involved in preventing a possible NEO impact event?

1. The object needs to be found in space and observed over time. 2. An explosion is used to either nudge or destroy the object. 3. Models are used to determine the future path of the object.

Identify some of the features created during an impact event.

A: Ejecta B: Breccia C: Melted rocks

Complete the sentences describing the prevention of an NEO impact event.

An object far from Earth--could be gently nudged to deflect its path. An object close to Earth--would most likely need to be broken into smaller pieces.

Long-period comets come from the and have orbital periods in the hundreds to thousands of years.

Blank 1: Oort Blank 2: Cloud

If an asteroid were to make it through Earth's atmosphere and strike the surface, it would be a(n)________ ; if it exploded in the atmosphere, it would be a(n) _______

Blank 1: meteorite Blank 2: meteor

There are two different types of impact craters: ______craters are bowl-shaped and a few kilometers in diameter, whereas __________craters have a central peak and are greater than 4 kilometers in diameter.

Blank 1: simple Blank 2: complex

An NEO will create a crater that is to times larger than itself.Blank 1: ten or 10

Blank 1: ten or 10 Blank 2: twenty or 20

How do scientists date an impact crater event?

By determining the crater's relationship with the surrounding rocks

Which of the craters shown on this map is linked to the mass extinction event at the end of the Mesozoic 65 million years ago?

Chicxulub

Scientists believe that ______ may have been a primary source of water for Earth's oceans.

Comets

Which strikes Earth at a faster speed: comets or asteroids?

Comets

What kind of an impact crater is shown here on this moon of Saturn?

Complex

Most asteroids approaching Earth are ______ to see because they are small, dark, and moving quickly.

Difficult

What are the primary components of a comet?

Dirt and Ice

Match the effect of an NEO impact with Earth with its description. Note that not all of the effects are listed.

Earthquake:This would be the largest ever recorded and would be felt by people thousands of kilometers from the impact. Air blast: This would flatten everything for hundreds of kilometers. Ejecta fall: This would land as far as thousands of kilometers from the impact and block sunlight for months. Wildfires: Created by molten rock blasted from the crater, these would add smoke to the atmosphere. Gases: These could lead to increased temperatures and acid rain.

Which of the following natural hazards can be prevented?

Impact events

The stable orbit of an asteroid can be disrupted by another asteroid crashing into it, which itself was disrupted by the gravitational influence of ______.

Jupiter

The asteroid belt, which is the source location for asteroids, is located between what two planets?

Jupiter and Mar

Short-period comets come from the _____ and travel in the same direction as the outer planets. Multiple choice question.

Kuiper belt

Which are more common: large asteroids or large comets?

Large comets

The bus-sized meteor that broke apart over and near the city of Chelyabinsk, , in 2013 injured more than 1,000 people, mostly by flying glass; the force of the object shattered windows.

Russia

Which of the following are types of meteorites?

Stony-iron Stony Iron

How big is an impact crater compared to the size of the NEO that created it?

The crater is 10 to 20 times larger than the NEO.

Why is the current search for NEOs that might impact Earth concentrated on those over 1 kilometer in diameter?

They are large enough to create global-scale catastrophes.

Which of the following describe long-period comets?

They originate in the Oort Cloud. They have irregular elliptical orbits. They can have orbital periods into the thousands of years.

What sized objects are being targeted and identified in the current search for NEOs?

Those over 1 kilometer in diameter

The scale is used to assess the risk from impact events.

Torino

What is the name of the scale used to assess the potential risk from impact events?

Torino

True or false: Impact events can be prevented.

True

What factors affect the size of an impact crater? Multiple select question.

Velocity of the NEO Composition of the NEO Composition of the impact site Size of the NEO

What is the primary difference between a meteor and a meteorite?

Whether or not it strike the earth

If a meteorite the size of the one that created the Chixchulub crater hit Earth today, what is the estimated damage?

about billion people will die

Scientists can determine the age of a crater by determining the of the surrounding, disturbed rock.

age

While most of the physical results of impact cratering are macro in scale, extreme pressures can create ______ at the microscopic level.

altered minerals, i.e. shocked quartz

The source location of asteroids is the ______; its located between the planets Mars and Jupiter and is about 1 AU wide.

asteroid belt

Name one type of natural object that would create an impact crater upon collision with a terrestrial planet.

asteroid, comet, or meteorite

If a meteorite the size of the one that created the Chicxulub Crater hit Earth today, the damage would be ______.

catastrophic and worldwide

The Chicxulub impact in Mexico is associated with the mass extinction event that occurred at the end of the Mesozoic approximately 65 million years ago.

crater

Short-period comets are called that because they ______.

have orbital periods of 200 years or less

Asteroids leave their stable orbits within the asteroid belt because ______. Multiple choice question.

of the gravitational influence of Jupiter

Most impact craters on terrestrial planets and their moons were created ______. Multiple choice question.

over 3.1 billion years ago

The size of an impact crater is determined by the and velocity of the NEO and the compositions of both the NEO and the impact site.

size or diameter

How easy is it for scientists to detect NEOs approaching Earth, most of which are asteroids?

very hard

As comets contain a significant amount of ice and the early Earth was buffeted with comet impacts, these may have served as a source of ______.

water for the ocean