Question 1

Why were asteroids not discovered until the 19th century?

Accepted Answer

Asteroids are generally small in comparison to planets and require a good telescope and patient searching to spot them. This is why they were not discovered until the 19th century when telescopes became more advanced and astronomers began focused searches for them.

Question 2

According to astronomical tradition, who gets to suggest the name for a newly discovered asteroid?

Accepted Answer

According to astronomical tradition, the discoverer of the asteroid gets to suggest the name for the newly discovered asteroid. This tradition has been in place since the early 1800s.

Question 3

One reason we know more about the surface composition of the asteroid Vesta than about most other members of the asteroid belt is that

Accepted Answer

Pieces of Vesta have landed on Earth as meteorites, which have been studied in detail and provide information about Vesta's surface composition.

Question 4

More than 75% of the known asteroids:

Accepted Answer

More than 75% of the known asteroids can be found in the asteroid belt between Mars and Jupiter.

Question 5

The Shoemaker-NEAR spacecraft explored two asteroids, Mathilde and Eros. A big difference between them is that:

Accepted Answer

Mathilde appears to be a pile of "rubble" composed of separate rocks, while Eros is a solid asteroid. This difference is believed to be due to their different histories of formation and evolution.

Question 6

Why do astronomers today think that we have an asteroid belt and not a planet between Mars and Jupiter?

Accepted Answer

Jupiter's strong gravity disrupts the formation of a planet between Mars and Jupiter. This gravitational disruption causes asteroids to continuously collide with each other and break apart, preventing them from forming into a planet.

Question 7

In the far future, an entrepreneur with a large fleet of space ships decides to capture and bring to Earth some valuable asteroids. If at that time, there is a shortage of usable metals on Earth, what type of asteroids should his employees search for?

Accepted Answer

M-type asteroids are metallic and contain high concentrations of metals like nickel and iron, making them valuable for mining when there is a shortage of usable metals on Earth.

Question 8

The fact that some asteroids cluster in what are called asteroid families is probably the result of:

Accepted Answer

Collisions which broke up larger bodies into a number of smaller ones is the most widely accepted theory for the formation of asteroid families. This theory suggests that the asteroid belt was once populated by larger bodies, which collided and broke up into smaller fragments that we observe today. These fragments can sometimes share common orbits and form asteroid families. Resonances with the jovian planets and comets passing through the asteroid belt can also affect the orbits of asteroids, but they are not responsible for the formation of asteroid families. Strong magnetic fields found in some asteroids are not sufficient to form asteroid families. Random chance is also unlikely to be the sole reason for the clustering of asteroids into families.

Question 9

When the Dawn spacecraft explored the largest asteroid Ceres, it discovered white spots that appear to be salt and volcanic mountains made of water ice. This led astronomers to which of the following ideas:

Accepted Answer

The discovery of white spots that are likely salt and volcanic mountains made of water ice suggest that Ceres may have (or may have had) a liquid ocean under its crust, making C the best choice. Options A, B, and D are not supported by the discoveries on Ceres. Option E is a humorous distractor.

Question 10

In 2013, a small stony asteroid collided with the Earth above the Russian city of Chelyabinsk. What was the result?

Accepted Answer

The collision resulted in a fireball brighter than the Sun that could be seen in the sky.

Question 11

Two small moons in the solar system, known since the 19^th century, turn out to be captured asteroids. These two moons are:

Accepted Answer

Phobos and Deimos are the only two moons in the solar system that are believed to be captured asteroids.

Question 12

Astronomers have realized that the surface of Ida is older than the surface of Gaspra. How do they measure this?

Accepted Answer

Astronomers can measure the age of a planetary body's surface by counting the number of impact craters. The more craters a surface has, the older it is, since more time has passed for objects to come crashing into it. Ida has more craters on its surface than Gaspra, indicating that it is older.

Question 13

A baseball pitcher wants to impress his girl-friend with how strong his throwing arm is. On which of the following bodies would the pitcher be MOST likely to be able to throw a baseball (a fast ball) so fast it would actually go into orbit?

Accepted Answer

The ability to throw a baseball into orbit around a celestial body depends on the body's gravity and escape velocity. Asteroid Ida has significantly lower gravity and escape velocity compared to Earth, Mars, Ganymede, and Titan, making it the most likely place where a human could throw a baseball fast enough for it to go into orbit.

Question 14

If there are at least a million asteroids, how did spacecraft like Galileo survive their trip through the asteroid belt?

Accepted Answer

Although there are many asteroids in the belt, they are widely spaced out, and therefore spacecraft can safely navigate through the belt without colliding with any asteroids. The spacecraft can also be guided along a specific path to avoid any potential collisions. Option A is not entirely accurate as NASA spacecraft do not always travel above or below the asteroid belt, and can fly through the middle of the belt as well. Option B is not a current technology used by spacecraft to maneuver through the asteroid belt. Option D is not entirely accurate as some asteroids in the belt can be much larger than a centimeter across. Option E is also not accurate as NASA has not lost a dozen spacecraft to collisions with asteroids.

Question 15

The two asteroids from which close-up images and data have been returned by the Galileo spacecraft are:

Accepted Answer

The Galileo spacecraft returned images and data of two asteroids named Ida and Gaspra during its mission.

Question 16

The first asteroid to be discovered (which is also the largest one) is called

Accepted Answer

Ceres was the first asteroid to be discovered, on January 1, 1801 by Italian astronomer Giuseppe Piazzi. Ceres is also the largest asteroid in the asteroid belt between Mars and Jupiter, with a diameter of about 590 miles (940 kilometers).

Question 17

How have astronomers learned what different asteroids are made of?

Accepted Answer

Astronomers examine the spectrum of the sunlight that reflects from the asteroid to determine its composition. Different chemical elements absorb and reflect different wavelengths of light, creating a unique spectral fingerprint that can be used to identify the asteroid's composition.

Question 18

The first asteroid confirmed to have a satellite (moon) was

Accepted Answer

Ida was the first asteroid confirmed to have a satellite (named Dactyl) in 1993 by the Galileo spacecraft.

Question 19

A main difference between asteroids and comets is that asteroids are mostly made of rock and comets are mostly made of

Accepted Answer

Comets are mostly made of ice, along with dust and small rocky particles. This is why they have a "tail" when they get close to the sun - the ice sublimates (turns from solid to gas) and carries dust and particles with it. Asteroids, on the other hand, are mostly made of rock and metal.

Question 20

Different asteroids reflect different percentages of the light falling on them. This is due to the fact that they have different:

Accepted Answer

The composition of an asteroid affects how much light it reflects, as some materials are more reflective than others. The other choices are not directly related to light reflection.

Quiz 13: Comets and Asteroids: Debris of the Solar System