T2: Lec 15-16 Flashcards
(30 cards)
Key features of Gas Giants?
extended atmosphere with mainly Hydrogen and Helium atmosphere. Very large, thick atmosphere being dominant of the planet, likely a rocky or iron core
(Saturn and Jupiter)
Key features of Ice Gaints?
made with more ice and heavier elements like water, methane, and ammonia. Smaller and thinner atmospheres than gas giants, have rocky or icy cores.
(e.g. Neptune and Uranus)
Describe Jupiter and its key features as a gas giant:
*Most massive star
*Certainly not a failed star - way too small for that (have to be 10-100x larger)
*Massive and large (earth fits in Jupiter’s eye)
*Red spot - hydrogen storm that may or may not be permanent
Explain Saturn and its Key Features as a Gas giant:
Almost as large as Jupiter, but not as massive.
Many rings - some faint some thick and visible → rings come from tidal forces!!
Space rock → Roche Limit → Rings
What is the Roche Limit?
Gravitational Force Pulling an object into another planets orbit that at a certain point (or distance within the gravitational force) becomes too much fro the object to withstand and begins to break apart.
Point at which limit is changes with mass of the object and the planet
This breaking of objects made Saturn’s rings
Why is Uranus on its Side?
Likely due to a large collision with an Earth-sized object taht smashed and flopped Uranus over (similar to giant Impact hypothesis)
Describe Uranus’ key features and discovery as an Ice giant?
*Blue because of Methane atmosphere that absorbs red light
*Found on March 13, 1781 by Willium Herscahl and his sister through a telescope. Saw how slow it was going, so it must be a distant planet
*Turns on its side (97 tilt) - causes “days” to be different from its rotation as the whole hemisphere is on its side, not turning around the whole planet like Earth
*Seasons - whole hemisphere is in summer or winter.
What si tidal heating?
processes where a celestial body’s interior heats up due to flexing and squeezing experienced from gravitational pull from another body from the tidal forces.
how does tidal heating drive processes on Moons in the outer solar system?
Tidal heating causes Jupiter’s Moon, Io, to be geologically active with hundreds of active volcanoes due to its heated interior.
Callisto not affected as its the furthest away
What are small bodies?
objects Sun in space, and aren’t planets nor natural satellites mainly found in Asteroid or Kuiper Belt (these objects can actually move between belts)
Likely left over from planet formation during Solar Nebula Theory that weren’t blasted away by solar wind
why do small bodies typically have strange shapes?
due to having not enough mass to become spherical, with some even having moons of their own (some are in binary asteroid systems)
What are near-Earth objects?
asteroid or comet whose orbit brings it close to Earth’s orbit, but end up not hitting earth (DART - unit helping to redirect asteroids in order to avoid asteroids hitting earth)
What is Planet 9?
the possible 9th planet in the solar system that vary vaguely orbits the sun
shepherds Kuiper Belt objects due to phenomena that orbits faintly and very far away
yet to be found
how did earth get its water?
Origin of earth’s Water and oceans came from impacting asteroids and shit from Kuiper belt or Oort cloud objects that melted on Earth’s surface.
how do meteor showers happen?
Meteor showers - due to comets close to the sun breaking off material that Earth ends up going through. The small bits of rock and debris Earth enters from comet’s tails is burned up in the atmosphere causing meteor showers and more shooting stars visible in the ight sky.
What is an Exoplanet?
a planet that isn’t in out solar system.
First exoplanet (51 Pegasi B) found in 90s orbiting pulsar star (51 Pegasi).
Slightly larger than Jupiter, but hotter, very fast orbit, and very close to sun (likely was pulled closer).
Exoplanet detection techniques and biases:
(just the names)
- Block Starlight
- Transit Method
- Gravitational Microlensing
- Radial Velocity
- Detection Method
Explain the Block sunlight exoplanet Detection method:
blocking star light for direct imaging methods to see planet’s light and movements (kinda difficult)
Bias - easier to find direct detecting methods for larger, massive, and more distant planets from their sun.
You can physically block starlight (using a flower cover) which still allows planet light through.
Explain the Transit Method exoplanet Detection method:
an indirect method that uses starlight graphs and the transit of the exoplanet in front of the star to find them. When planets pass in front of the sun and block starlight, this shows as a dip on the graph, indicating an exoplanet is there.
Bias - easier to detect larger planets as they cause larger dips in the graph. Least biased towards more massive stars
Explain the Radial Velocity exoplanet Detection method:
Looks for gravitational effects of planets on the star (tidal forces). The stars end up moving closer or further away (a wobble in a circular motion) which can be seen as the star oscillates from blueshift to redshift.
Bias - the planet must be massive enough to have strong enough gravitational forces, to cause a wobble to be detectable,
Explain the Gravitational Microlensing exoplanet Detection method:
Mass of planet curves space time between star and earth observation. Pictures of the star from Earth show a change in magnification of the star as the planet would move infront of it, causing a gravitational lens where light is directed twice to Earth around the planet. The lens magnifies and makes the star look bigger and brighter.
Shown as a second peak in the gravitational lens graph thing (idk the name) as the planet passes in front of the star causing the lense.
Biased - towards larger planets as this causes a more noticeable spike in the graph and increase in the gravitational lense and photos taken.
What types of exoplanets have we discovered?
Neptune-like planets (35%)
Gas Giants (30%)
Super earths (31%) - exoplanets that range between earth’s size and Naptune’s size that might be rocky and shrouded in a puffy atmosphere.
Terrestrial (4%)
*Most exoplanets are organized into what we already know - “Hot Jupiters”, “Cold Neptunes.”
What is the Habitable Zone?
he narrow region around a star where liquid water can form depending on the radius of orbit, and relative mass, and temperature of the star.
Hotter stars have a HZ further out. These zones are NOT consistently the same! As the stars evolve the habitable zone changes with the temperature and size.
Being in the zone doesn’t mean the planet is habitable - some don’t have water, some don’t have enough pressure and gravity. (e.g. Kepler)
What are some Possible Challenges with Mars Terraforming?
(name and explain)
- amosphere - rom mars itself, there’s not enough material from CO2 to work with to melt and form an atmosphere. This material would have to come from somewhere else.
- magnetic field - if we somehow made the atmosphere on Mars, it has no protective magnetic field. We would have to engineer an artificial magnetic shield between mars and sun to protect it against solar wind and rays.
- no water ice - even thought there’s ice on Mars, its only CO2 ice caps that form then sublimate
