(A) Topic 12 wrongs

Question 1

Define the term proper motion

Answer 1

The motion of the star across the celestial sphere at right angles to the observer’s line of sight

Question 2

What is gravitational attraction responsible for?

Answer 2

orbits

Question 3

What is the barycentre?

Answer 3

Centre of mass of two or more bodies which orbit each other and is the point at which bodies orbit

Question 3

What additional effects does the moon’s tidal effect on earth produce?

Answer 3

Causes moon to lose momentum + moves it further away; also causes moonquakes

Question 4

What is tidal heating and what does it result in over time?

Answer 4

Increase in the thermal content of a planet or moon associated with the differential gravitational force between 2 bodies in orbit. Results in a synchronous orbit

Question 5

Define orbital resonance

Answer 5

2 or more bodies orbiting another larger body have orbital periods that have a gravitational effect on one another so their orbital periods use a time ratio

Question 6

What are lagrangian points?

Answer 6

Locations relevant to 2 bodies where a smaller object can maintain a position in orbit

Question 7

Name an example of an accidental collision

Answer 7

Moon’s significant impact crater near the south pole called the Aitken Basin

Question 8

What are the effects of solar wind?

Answer 8

• aurorae
• geomagnetic storms
• satellite orbits affected due to high temperatures
• comet tails

Question 9

Define the Roche limit

Answer 9

The minimum distance to which a large satellite can approach its parent body without being torn apart by tidal forces

Question 10

How does the interaction between a body’s gravitational and elastic forces affect its shape?

Answer 10

If the body doesn’t build enough mass, it will not be able to combat the elastic forces and therefore will not form a sphere

Question 11

What is a ‘hydrostatic equilibrium’?

Answer 11

An object is symmetrically shaped either a spheroid or ellipsoid

Question 12

What opposing factors determine the presence of an atmosphere?

Answer 12

Body mass and temperature

Question 12

How were the gas giants formed?

Answer 12

Internal radioactive heating caused cores to melt and less dense materials to rise upwards which creates slushy mantles for the gas giants

Question 13

Define astrometry

Answer 13

Measuring the position of a star very carefully and any minute wobbles in the star’s position can be due to the tiny pull of a planet on the parent star

Question 14

Define transit as a method to detect exoplanets

Answer 14

Watching a planet’s transit in front of a star, which can be used to work out the size and orbit of a planet

Question 14

Define radial velocity

Answer 14

Changes in the movement of a star towards and away from Earth detected using the Doppler effect

Question 15

Why do scientists believe that life could exist on Titan?

Answer 15

• possesses a substantial nitrogen-rich atmosphere
• has lakes of methane on its surface
• organic compounds discovered on its surface

Question 16

Why do scientists believe that life could exist on Enceladus?

Answer 16

• spews geysers of water into space from its south polar region
• other plumes include ammonia, carbon dioxide and hydrcarbons

Question 17

What is the habitable zone?

Answer 17

An area surrounding a star in which a planet can have liquid water at its surface. If water is present, life would be too

Question 18

What is the Drake equation?

Answer 18

Model for scientists to estimate the probability of life and intelligent civilisations that use at least the same technology as us elsewhere in the galaxy

Question 19

What does the organisation SETI do?

Answer 19

Listen to radio waves of the galaxy likely to have the conditions for life

Question 20

Name 3 benefits and risks of discovering extra-terrestrial life

Answer 20

pros: - lead to cures for existing illnesses
- may share knowledge about science
- may share advances in technology
cons: - create a new bacteria capable of killing all life
- dependence on them for knowledge prevents human advancement
- hostile + set out to invade earth forms