Question 1

Why does the plasma tail of a comet always point away from the Sun?

Accepted Answer

The solar wind, which is a stream of charged particles emitted by the Sun, interacts with the ions in the comet's plasma tail, causing it to always point away from the Sun.

Question 2

What part of a comet points most directly away from the Sun?

Accepted Answer

The plasma tail is the part of a comet that points most directly away from the Sun. This is because the plasma tail is made up of charged particles which interact with the magnetic field of the Sun, causing the tail to be swept away from the Sun in a straight line. The other options (nucleus, coma, jets of gas, and dust tail) may also have some directional components but not as direct as the plasma tail.

Question 3

When was Pluto discovered?

Accepted Answer

Pluto was discovered on February 18, 1930, by astronomer Clyde Tombaugh.

Question 4

Primitive meteorites can be distinguished from other meteorites and terrestrial rocks because they

Accepted Answer

Primitive meteorites contain a noticeable fraction of pure metallic flakes, which distinguishes them from other meteorites and terrestrial rocks.

Question 5

Which of the following does not lend support to the idea that Pluto is a Kuiper-belt object?

Accepted Answer

The fact that Pluto is regarded by many to be a planet does not necessarily support the idea that it is a Kuiper-belt object. In fact, it was originally classified as a planet before being reclassified as a dwarf planet, which is also a type of Kuiper-belt object. The other options all provide support for the idea that Pluto is a Kuiper-belt object, including its cometlike composition and density (A), the presence of moons around asteroids (C), its more eccentric orbit than other planets (D), and the existence of other Kuiper-belt objects that are large (E).

Question 6

In the asteroid impact theory of the extinction of the dinosaurs some 65 million years ago,the dinosaurs (and over half of all the other species on Earth at that time)died off largely because

Accepted Answer

The dust injected into the stratosphere from the impact absorbed visible light from the Sun, causing global temperatures to plummet. This led to a dramatic cooling of the planet and disrupted the food chain, ultimately leading to the extinction of the dinosaurs and many other species.

Question 7

Where did comets that are now in the Kuiper belt originally form?

Accepted Answer

Comets in the Kuiper Belt are believed to have formed near their current orbits, just beyond Neptune, in the cold outer regions of the early solar system. This location provided the conditions necessary for the accumulation of ice and rock, characteristic of Kuiper Belt objects.

Question 8

Processed meteorites with low metal content probably are

Accepted Answer

Processed meteorites with low metal content are likely chunks of a larger asteroid that was shattered by a collision, as they have undergone differentiation and processing, which reduces metal content.

Question 9

Where did comets that are now in the Oort cloud originally form?

Accepted Answer

Comets in the Oort cloud are believed to have originally formed near the jovian planets and were later ejected to the distant Oort cloud by gravitational interactions.

Question 10

In order to have a comet named after you,you have to

Accepted Answer

According to the regulations of the International Astronomical Union (IAU), a comet is named after the first three discoverers who report it to the organization. Calculating its orbit, publishing a picture of it, or being a well-known astronomer are not requirements for having a comet named after you.

Question 11

Most meteorites are

Accepted Answer

Most meteorites are composed of rocky materials and are considered "primitive" because they are unchanged since their formation in the early solar system. While there are some carbon-rich meteorites, they are less common than the rocky ones. Additionally, meteorites that have undergone significant processing or alteration are also less common.

Question 12

Halley's comet is named after the English scientist Edmund Halley because he

Accepted Answer

Edmund Halley was responsible for calculating the orbit of the comet and predicting its return in 1758. This prediction was based on his study of previous comet sightings and his belief that they were all part of the same comet returning on a regular cycle. His prediction was proven correct when the comet that came to be known as Halley's comet returned as predicted.

Question 13

Comets with extremely elliptical orbits,like comets Hyakutake and Hale-Bopp,

Accepted Answer

Comets with extremely elliptical orbits, like Hyakutake and Hale-Bopp, are believed to come from the Oort Cloud, which is a hypothetical cloud of icy objects surrounding the Solar System beyond the Kuiper Belt. These comets can be influenced by the gravitational pull of nearby stars, causing their highly elongated orbits to bring them close to the Sun.

Question 14

The number of comets in the Oort cloud is probably about

Accepted Answer

The Oort Cloud is believed to contain around a trillion comets. It is a theoretical cloud of predominantly icy objects that is thought to surround the Sun at a distance of up to 100,000 astronomical units. This vast number of comets contributes to the reservoir from which long-period comets originate.

Question 15

Why won't Pluto collide with Neptune?

Accepted Answer

Pluto and Neptune are in a 3:2 orbital resonance, meaning for every three orbits Pluto completes around the Sun, Neptune completes two. This resonance stabilizes their orbits, preventing them from colliding despite their orbits crossing paths.

Question 16

Meteorites can come from

Accepted Answer

Meteorites can come from the cores of asteroids, the Moon, Mars, and comets. Therefore, the best choice is E, which includes all of the mentioned sources.

Question 17

When do comets generally begin to form a tail?

Accepted Answer

Comets generally begin to form a tail inside of Jupiter's orbit, where the Sun's radiation is strong enough to sublimate the comet's ices into gas, which then gets blown away by the solar wind, creating a tail.

Question 18

What is Charon?

Accepted Answer

Charon is known as the largest moon of the dwarf planet Pluto.

Question 19

What characteristic distinguishes a meteorite from a terrestrial rock?

Accepted Answer

All of the above characteristics distinguish meteorites from terrestrial rocks. Meteorites are usually covered in a dark crust from the heat of entering Earth's atmosphere, they often have high metal content, they contain different isotopes of certain elements compared to terrestrial rocks, and they may contain rare elements not found in terrestrial rocks.

Question 20

What is the typical size of comets that enter the inner solar system?

Accepted Answer

Comets that enter the inner solar system typically have nuclei around 10 km in size, although they can vary.

Quiz 12: Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts