Topic 12 - Formation of planetary systems Flashcards
What is gravitational attraction?
It produces regular motion, including the orbits of planets and moons.
What are some effects of tidal gravitational forces?
Ring systems, asteroid belts, internal heating.
What do we know about planetary ring systems?
The combined gravitational effects of Jupiter and its moons keeps the rings stable.
What do we know about the asteroid belts?
It has enough material to form small planets buts the tidal forces of Mars and Jupiter prevent anything larger than Ceres forming.
What is internal heating?
- Tidal forces stretch and compress a planet
- This creates tidal heating which creates synchronous rotation
What is special about Io?
- It is volcanically active due to the forces from Jupiter
- It’s average surface temperature is -130°C but it’s volcanoes reach 1650°C
What is chaotic motion?
Gravitational forces mean that interactions between more than two bodies can lead to unpredictable and chaotic behaviour.
What are resonances?
Planets and moons orbit with their orbit times in constant motion.
What do resonances do?
It makes planetary orbits more stable and reduces collisions.
Pluto and Neptune’s Resonance:
Pluto makes two orbits of the Sun for every three of Neptune ( makes it impossible for Pluto and Neptune to collide)
Jupiter’s Moons’ Resonance:
Io, Europa and Ganymede are in a 4:2:1 orbital resonance with each other
What are Lagrange Points?
Locations relative to two bodies where a smaller object can maintain a stable position.
List the Lagrange Points in order, clockwise and inwards.
L4, L2, L1, L5, L3
List evidence of collisions:
- Uranus’ extreme orbital tilt
- Impact craters on moons
- Earth’s axial tilt (23.5°)
- Venus’ retrograde spin
What does solar wind cause?
- Planets to lose their atmosphere
- Causes Aurorae
- Causes ion tails on comets
- Forms the heliosphere
What is the Roche Limit?
- The minimum distance a large moon can approach a planet without being torn apart
- 2.5 times the planet’s radius
What has to occur for a planet or moon to have an atmosphere?
- It has a high enough gravitational field
- It isn’t too hot for gases to escape into space
- It isn’t exposed to a strong solar wind
List the methods for discovering exoplanets:
- Transit Method
- Astrometry Method
- Radial Velocity Method
What is the Transit Method?
- When an exoplanet moves in front of its star, it blocks light
- This tells us the planet’s size and distance from its star
What is the Astrometry Method?
An exoplanet will cause its star to wobble. Powerful telescopes can detect this.
What is the Radial Velocity Method?
An exoplanet will cause its star to wobble.
By observing the light, the shift in wavelength will tell us if the star is wobbling.
What is the Goldilocks (Habitable) Zone?
Region where liquid water can be found on the planet’s surface.
What does SETI stand for?
Search for Extra-Terrestrial Intelligence
What is the Drake Equation?
N = R* x fp x ne x fl x fi x fc x L
