Unit 2 Comets and Meteors

Question 1

What is a comet?

Answer 1

A comet is a ball of rock and ice that have tow tails.

Question 2

What are the two tails of a comet?

Answer 2

The ion tail (points away from the Sun) and the dust tail (points in the direction the comet has travelled from).

Question 3

What are the two categories of comet?

Answer 3

Short period comets (orbital period of less than 200 years and originate from the Kuiper Belt) and long period comets (originate from the Oort Cloud).

Question 4

Name a famous short period comet.

Answer 4

Eg: Comet Halley.

Question 5

Is there evidence for the Oort Cloud?

Answer 5

There is no direct evidence but there is very strong evidence that suggests its existence.

Question 6

What is the Coma of a comet?

Answer 6

The coma is the heated gas and dust that forms around the comet’s nucleus as it approaches the Sun.

Question 7

What is a meteoroid?

Answer 7

Meteoroids are small rocky irregular sized lumps of rock that can range in size from micrometres to several metres. Some may have some iron-nickel content.

Question 8

What does the Royal Astronomical Society propose is the difference between a meteoroid and a small asteroid?

Answer 8

It must be over 10 metres in size to be an asteroid.

Question 9

Give some examples of the origins of a meteoroid.

Answer 9

Broken fragments of colliding asteroids.
Impacts with planets.
Some originate from dust tails of comets forming groups called meteoroid streams.

Question 10

What is a meteor?

Answer 10

A meteor is a meteoroid that has entered the Earth’s atmosphere and produces a short streak of light as it burns up due to friction.

Question 11

What is a fireball?

Answer 11

A meteor with a magnitude of -3 or brighter.

Question 12

What is a meteorite?

Answer 12

A piece of meteor that survives the descent to Earth and lands on the Earth’s surface.

Question 13

What are the 3 classifications of meteorites?

Answer 13

Stones, irons and stoney-irons. It depends upon the ratio of rock to metal.

Question 14

What is a meteor shower?

Answer 14

When the Earth passes through the meteoroid stream in the wake of a comet, the debris enters the Earth’s atmosphere and a meteor shower is the burning up of the dust in the atmosphere.

Question 15

What is the radiant?

Answer 15

The apparent point in the sky that the meteors diverge from during a meteor shower.

Question 16

How are meteor showers named?

Answer 16

By the constellation in which the radiant appears in. Eg: Perseids shower lies in Perseus.

Question 17

What is a PHO?

Answer 17

It is a Potentially Hazardous Object.

Question 18

What is a NEO?

Answer 18

It is a Near Earth Object whose trajectory might bring them within 0.3 AU. In 2008 about 5600 NEOs were known.

Question 19

How close is a PHO?

Answer 19

Less than 0.05 AU. In 2008 about 1000 had been identified.

Question 20

Examples of collisions in the Solar System.

Answer 20

The Moon and other planets have craters.
Venus and Uranus rotate on their axis “backwards” and “sideways” respectively; both are thought to be consequences of gigantic collisions early in the Solar System.
Rock samples of the Moon show that it may be the result of a collision with the Earth.
Chicxulub Crater in Mexico.
Barringer Crater Arizona.

Question 21

True or false, most PHOs have a high chance of inflicting damage on Earth.

Answer 21

False, most PHOs have little chance of inflicting damage. It is PHOs with a diameter greater than 1 km that pose a threat on a global scale.

Question 22

What is the Torino Scale?

Answer 22

It is the scale that is used to categorise the risk posed by a PHO. 0 to 1 is a near miss whilst 10 is a certain impact that could be capable of world-wide devastation.