(A) Topic 12 wrongs Flashcards
Define the term proper motion
The motion of the star across the celestial sphere at right angles to the observer’s line of sight
What is gravitational attraction responsible for?
orbits
What is the barycentre?
Centre of mass of two or more bodies which orbit each other and is the point at which bodies orbit
What additional effects does the moon’s tidal effect on earth produce?
Causes moon to lose momentum + moves it further away; also causes moonquakes
What is tidal heating and what does it result in over time?
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
Define orbital resonance
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
What are lagrangian points?
Locations relevant to 2 bodies where a smaller object can maintain a position in orbit
Name an example of an accidental collision
Moon’s significant impact crater near the south pole called the Aitken Basin
What are the effects of solar wind?
- aurorae
- geomagnetic storms
- satellite orbits affected due to high temperatures
- comet tails
Define the Roche limit
The minimum distance to which a large satellite can approach its parent body without being torn apart by tidal forces
How does the interaction between a body’s gravitational and elastic forces affect its shape?
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
What is a ‘hydrostatic equilibrium’?
An object is symmetrically shaped either a spheroid or ellipsoid
What opposing factors determine the presence of an atmosphere?
Body mass and temperature
How were the gas giants formed?
Internal radioactive heating caused cores to melt and less dense materials to rise upwards which creates slushy mantles for the gas giants
Define astrometry
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
Define transit as a method to detect exoplanets
Watching a planet’s transit in front of a star, which can be used to work out the size and orbit of a planet
Define radial velocity
Changes in the movement of a star towards and away from Earth detected using the Doppler effect
Why do scientists believe that life could exist on Titan?
- possesses a substantial nitrogen-rich atmosphere
- has lakes of methane on its surface
- organic compounds discovered on its surface
Why do scientists believe that life could exist on Enceladus?
- spews geysers of water into space from its south polar region
- other plumes include ammonia, carbon dioxide and hydrcarbons
What is the habitable zone?
An area surrounding a star in which a planet can have liquid water at its surface. If water is present, life would be too
What is the Drake equation?
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
What does the organisation SETI do?
Listen to radio waves of the galaxy likely to have the conditions for life
Name 3 benefits and risks of discovering extra-terrestrial life
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
