Question 1

If an impact crater on Earth is 2000 m wide, approximately how big would the asteroid fragment have been that survived its passage through the atmosphere?

Accepted Answer

According to the known impact crater size versus asteroid size relationship, the diameter of the asteroid fragment that would create a 2000 m wide crater on Earth would be approximately 10 times the diameter of the crater, which is 200 m. However, not all of the asteroid survives the passage through the atmosphere, so the size would be reduced further. Therefore, the closest answer is B - 100 m.

Question 2

Statistically, an asteroid 1 km in diameter might be expected to strike Earth:

Accepted Answer

Asteroids of this size are expected to strike Earth approximately once every 500,000 years based on statistical models and historical data.

Question 3

Stony meteorites:

Accepted Answer

Stony meteorites are composed of rocks that are similar to terrestrial rocks, specifically igneous and metamorphic rocks. They make up the majority of meteorites that are found on Earth.

Answer: B 
 Some stony meteorites contain carbon and organic compounds such as amino acids, as well as water-bearing minerals. This has led to the hypothesis that these meteorites may have played a role in the origin of life on Earth.

Answer: C 
 Stony-iron meteorites have a combination of solid iron-nickel cores and rocky silicate shells, but stony meteorites do not have solid iron cores.

Answer: D 
 This is incorrect as stony meteorites are not primarily composed of solid iron and nickel. They may contain small amounts of these elements, but they are not the dominant components.

Question 4

Iron meteorites:

Accepted Answer

Iron meteorites are typically composed of 90-95% iron and 5-10% nickel, with small amounts of other elements such as cobalt, phosphorus, and iridium. Carbon is also present in some iron meteorites but not in significant amounts. The high iron content is due to the differentiation and segregation of molten metal from the rest of the solar system's protoplanetary disk.

Question 5

Although there is no official dividing line, a chunk of rock orbiting the Sun is generally considered an asteroid rather than a meteoroid if it:

Accepted Answer

According to the International Astronomical Union, an asteroid is any object in our solar system that is larger than 1 meter across, while a meteoroid is smaller than 1 meter across. Therefore, an object that is larger than 1 m is considered an asteroid, making choice B the correct answer.

Question 6

Some meteorites have been identified as coming from other bodies in our solar system. Which of the following is NOT one of those sources?

Accepted Answer

Meteorites have been identified as coming from the Moon, Mars, and Vesta, but not from Ceres.

Question 7

Which of the following descriptions would allow you tentatively to identify a rock as a fallen meteorite?

Accepted Answer

A solid iron rock with a distinctive crystal structure throughout its interior is one of the characteristics of a fallen meteorite.

Question 8

The Widmanstätten pattern uncovered by acid etching of the surfaces of many iron meteorites consists of:

Accepted Answer

The Widmanstätten pattern is formed by the slow cooling of large crystals in iron meteorites over millions of years, resulting in a distinctive pattern of interlocking crystal structures visible on the surfaces of the meteorites.

Question 9

An iron meteorite, when cut open and etched with acid, often shows a peculiar pattern of nickel-iron crystals called a Widmanstätten pattern. What does the presence of this pattern tell us about the meteorite?

Accepted Answer

The Widmanstätten pattern indicates slow cooling within the core of a large asteroid, suggesting the parent body was at least 200 km in diameter to allow for such cooling rates.

Question 10

An iron meteorite, when cut open and etched with acid, often shows a peculiar pattern of nickel-iron crystals called a Widmanstätten pattern. Through what process was this pattern created?

Accepted Answer

The Widmanstätten pattern is created through slow crystal growth as molten iron cools and solidifies in the interior of a large asteroid. This pattern is a result of the nickel-iron alloy in the meteorite cooling slowly over millions of years, allowing the formation of interlocking crystals of different compositions and orientations.

Question 11

A typical iron meteorite shows a Widmanstätten pattern. This suggests that it is a(n):

Accepted Answer

The Widmanstätten pattern is formed due to the slow cooling of the iron-nickel alloy in the core of a differentiated asteroid. This cooling process creates a distinctive pattern of interlocking crystals of two different mineral species, which is visible on the surface of the iron meteorite. Therefore, a typical iron meteorite showing a Widmanstätten pattern is likely a fragment from the core of a differentiated asteroid.

Question 12

The fact that there are several distinct and different types of meteorites (stony, stony iron, and iron) is probably indicative of:

Accepted Answer

The differentiation of asteroids, where heavier materials sink to the center and lighter materials rise to the surface, results in the formation of separate layers of iron, stony iron, and stony meteorites. The fragmentation of these differentiated asteroids could explain the existence of different types of meteorites.

Question 13

Widmanstätten patterns uniquely identify samples as iron meteorites. Why is this?

Accepted Answer

Widmanstätten patterns are formed by the slow cooling of iron meteorites over millions of years, resulting in the growth of interlocking crystals. This process is unique to iron meteorites and does not occur on Earth.

Question 14

A meteorite is a solid object reaching Earth's surface after plunging through our atmosphere. A meteorite might have originally been a part of any of the following EXCEPT:

Accepted Answer

The Van Allen radiation belt is made up of charged particles trapped by Earth's magnetic field, and is not a source of meteorites. A, B, and D are all potential sources of meteorites.

Question 15

The Tunguska event of 1908 was probably caused by a stony body. Why was so little obvious evidence of meteoric impact found at the scene?

Accepted Answer

The stony contents of the Tunguska event were distributed widely over the ground, but after a few years of weathering, they became indistinguishable from ordinary rocks. This is why little obvious evidence of meteoric impact was found at the scene.

Question 16

A stony meteorite might show evidence of each of the following EXCEPT ONE. Which is the EXCEPTION?

Accepted Answer

Stony meteorites do not show Widmanstätten patterns; these patterns are characteristic of iron meteorites.

Question 17

Which of the following biochemical materials has been found and identified in rocks recovered from outer space (e.g., meteorites)?

Accepted Answer

Amino acids have been found and identified in rocks recovered from outer space, specifically in meteorites. While viruses, living cells, lichens, and mosses are all living organisms or structures, none of them have been found in space rocks.

Question 18

The half-life for the decay of ²⁶Al into ²⁶Mg is 720,000 years. Suppose a meteorite was formed 4.6 billion years ago that contained ²⁶Al. How much ²⁶Al does it contain now?

Accepted Answer

The half-life of ²⁶Al is 720,000 years, meaning the amount of ²⁶Al halves every 720,000 years. Over 4.6 billion years, this process would have occurred approximately 6389 times (4.6 billion / 720,000), leaving almost none of the original ²⁶Al.

Question 19

A meteorite is seen to impact upon Earth and is found to contain significant amounts of ²⁶Mg, the stable decay product of radioactive ²⁶Al. What conclusion can be drawn from this observation?

Accepted Answer

The presence of significant amounts of ²⁶Mg, the stable decay product of radioactive ²⁶Al, suggests that an energetic nuclear event occurred near the Sun, possibly a supernova, at about the time that this meteorite was formed. This is because ²⁶Al is produced by the decay of unstable aluminum isotopes that are formed in such energetic events. This finding is not explained by options A, C, or D.

Question 20

What evidence do we have from meteorite studies that suggest that the formation of our Sun and solar system might have been triggered by a supernova explosion?

Accepted Answer

The discovery of the decay products of short-lived radioactive elements within some meteorites suggests that the materials that formed our solar system were exposed to an intense burst of radiation, which could have been caused by a nearby supernova explosion. This supports the theory that a supernova triggered the formation of our solar system. The other options (A, B, and C) do not directly support this theory.

Quiz 15: Asteroids, Comets, and Impacts

If an impact crater on Earth is 2000 m wide, approximately how big would the asteroid fragment have been that survived its passage through the atmosphere?

Statistically, an asteroid 1 km in diameter might be expected to strike Earth:

Stony meteorites:

Iron meteorites:

Although there is no official dividing line, a chunk of rock orbiting the Sun is generally considered an asteroid rather than a meteoroid if it:

Some meteorites have been identified as coming from other bodies in our solar system. Which of the following is NOT one of those sources?

Which of the following descriptions would allow you tentatively to identify a rock as a fallen meteorite?

The Widmanstätten pattern uncovered by acid etching of the surfaces of many iron meteorites consists of:

An iron meteorite, when cut open and etched with acid, often shows a peculiar pattern of nickel-iron crystals called a Widmanstätten pattern. What does the presence of this pattern tell us about the meteorite?

An iron meteorite, when cut open and etched with acid, often shows a peculiar pattern of nickel-iron crystals called a Widmanstätten pattern. Through what process was this pattern created?

A typical iron meteorite shows a Widmanstätten pattern. This suggests that it is a(n) :

The fact that there are several distinct and different types of meteorites (stony, stony iron, and iron) is probably indicative of:

Widmanstätten patterns uniquely identify samples as iron meteorites. Why is this?

A meteorite is a solid object reaching Earth's surface after plunging through our atmosphere. A meteorite might have originally been a part of any of the following EXCEPT:

The Tunguska event of 1908 was probably caused by a stony body. Why was so little obvious evidence of meteoric impact found at the scene?

A stony meteorite might show evidence of each of the following EXCEPT ONE. Which is the EXCEPTION?

Which of the following biochemical materials has been found and identified in rocks recovered from outer space (e.g., meteorites) ?

The half-life for the decay of ²⁶Al into ²⁶Mg is 720,000 years. Suppose a meteorite was formed 4.6 billion years ago that contained ²⁶Al. How much ²⁶Al does it contain now?

A meteorite is seen to impact upon Earth and is found to contain significant amounts of ²⁶Mg, the stable decay product of radioactive ²⁶Al. What conclusion can be drawn from this observation?

What evidence do we have from meteorite studies that suggest that the formation of our Sun and solar system might have been triggered by a supernova explosion?

Quiz 15: Asteroids, Comets, and Impacts

If an impact crater on Earth is 2000 m wide, approximately how big would the asteroid fragment have been that survived its passage through the atmosphere?

Statistically, an asteroid 1 km in diameter might be expected to strike Earth:

Stony meteorites:

Iron meteorites:

Although there is no official dividing line, a chunk of rock orbiting the Sun is generally considered an asteroid rather than a meteoroid if it:

Some meteorites have been identified as coming from other bodies in our solar system. Which of the following is NOT one of those sources?

Which of the following descriptions would allow you tentatively to identify a rock as a fallen meteorite?

The Widmanstätten pattern uncovered by acid etching of the surfaces of many iron meteorites consists of:

An iron meteorite, when cut open and etched with acid, often shows a peculiar pattern of nickel-iron crystals called a Widmanstätten pattern. What does the presence of this pattern tell us about the meteorite?

An iron meteorite, when cut open and etched with acid, often shows a peculiar pattern of nickel-iron crystals called a Widmanstätten pattern. Through what process was this pattern created?

A typical iron meteorite shows a Widmanstätten pattern. This suggests that it is a(n) :

The fact that there are several distinct and different types of meteorites (stony, stony iron, and iron) is probably indicative of:

Widmanstätten patterns uniquely identify samples as iron meteorites. Why is this?

A meteorite is a solid object reaching Earth's surface after plunging through our atmosphere. A meteorite might have originally been a part of any of the following EXCEPT:

The Tunguska event of 1908 was probably caused by a stony body. Why was so little obvious evidence of meteoric impact found at the scene?

A stony meteorite might show evidence of each of the following EXCEPT ONE. Which is the EXCEPTION?

Which of the following biochemical materials has been found and identified in rocks recovered from outer space (e.g., meteorites) ?

The half-life for the decay of 26Al into 26Mg is 720,000 years. Suppose a meteorite was formed 4.6 billion years ago that contained 26Al. How much 26Al does it contain now?

A meteorite is seen to impact upon Earth and is found to contain significant amounts of 26Mg, the stable decay product of radioactive 26Al. What conclusion can be drawn from this observation?

What evidence do we have from meteorite studies that suggest that the formation of our Sun and solar system might have been triggered by a supernova explosion?

The half-life for the decay of ²⁶Al into ²⁶Mg is 720,000 years. Suppose a meteorite was formed 4.6 billion years ago that contained ²⁶Al. How much ²⁶Al does it contain now?

A meteorite is seen to impact upon Earth and is found to contain significant amounts of ²⁶Mg, the stable decay product of radioactive ²⁶Al. What conclusion can be drawn from this observation?