ASTR 117 FINAL
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Formula to find surface temperature of a planet:
T= 2.898 x 10-3 m. x K ÷ [wavelength of the light being emitted IN METERS!!]
What are some myths about Mars that are transmitted via pop culture?
- -"face" on Mars proves there was civilization
- -canals on Mars were thought as proof of ancient civilization
What are the real conditions on Mars today? What difficulties would Earth life have to overcome to survive there?
- -thin atmosphere
- -both poles covered in ice
- -Jupiter knocks it off axis
About a billion years ago, Mars was very different than what it is today. Compare and contrast conditions on Mars at these two different times.
- -Then: had geological activity, had water gullys, possible oceans, had a mantle, had tectonic plates
- -Now: desert-like landscape, frozen water, has seasons, thin atmosphere, water below surface
How did Mars get to be in its current condition?
- -cooling magnetic core cause less convection and volcanic activity
- -atmosphere thinned out
- -doesn't have moon to keep it on axis
- -solar winds
What have past missions to Mars told us about the existence of life on the red planet?
- -might have been habitable
- -microbes in thing films of water?
- -contains elements of life
- -if axis tilted more, life might exist
In the 1900s, some scientists announced they found signs of life inside a martian meteorite. What was the evidence they put forward? Why do most astronomers today discount this evidence?
They claimed to have found nanobacteria, but it was disproven
Based on all the evidence we have gathered about Mars, could life there have originated the same way it did on Earth? Why or why not?
Yes because there is evidence of canals where water has run and there is still water on Mars but in ice form.
Several Mars missions are active right now and several more are due to be launched soon. Pick one or two of the most interesting-looking ones and discuss why they will try to find or have found already.
*Viking 1 and 2
- -orbiter and lander
- -landers did experiments with Mars soil
- -CO2 incorporating= fail
- -gas exchange experiment= fail
- -labeled release= success (live organisms used gas)
- -gas chromatograph= no organic molecules
What are the general characteristics of the moons around jovian planets and how is this different from the jovian planets themselves?
- The moons range from the size of large asteroids with a potato shape to spheres larger that Mercury. Most are made of rock and ice.
- This is different from the jovian planets because the Jovian planets are made of gases.
Why do we think thyat some of these moons could support life? (address all necessities of life!)
- some have water (ice)
- some have atmospheres and atmospheric pressure
- some may have geological activity/internal heat
- some have magnetic fields
Pick several of the jovian moons and rate their suitability for life based on the unique characteristics of these moons.
- 2) Callisto
- 3) Titan
- 4) Io
Of all the jovian moons you have studied, which one gets the award for most likely to support life?
What is the concept of a habitable zone?
- -region capable for life to exist
- -range of distances with abundance of water on planet
- -varies with each star
Where is the Sun's habitable zone?
between .4AU - 1.78AU
What specific conditions set the inner and outer boundaries of a star's habitable zone?
- -Inner: runaway greenhouse effect and moist greenhouse effect
- -Outer: thinning, cold atmosphere
How are the radical changes that occurred on Venus over billions of years different that those that occurred on Mars? Are any of these changes likely to happen on Earth?
- -Venus' changes were very fast when Mars' changes were a lot slower
- -these changes are not likely on Earth unless the Earth changes its orbit
If a planet is in a star's habitable zone, does that mean the planet will always be habitable?
What will happen to our Sun in about 4 billion years?
- -will exhaust its fuel
- -swell up to 100x size
- -will be 1000x brighter
- -turns red
- -become nebula or white dwarf
How will the changes to the Sun in about 4 billion years affect life on Earth?
- -Earth gets hot
- -water evaporates
- -we're toast
- -maybe engulfed into red giant Sun
- -complete darkness, if still standing
- -survival? if we could migrate...
What methods do climatologists use to measure the Earth's average temperature over decades? Hundreds of years?
- Decades: Measure coldest and hottest and take the average
- Centuries: Time scale
Astronomers have found that our Sun is NOT responsible for the current trend of global warming. According to your research, what is responsible?
- -buildup of CO2
- -increased fossil fuel use
How does the Sun rank in terms of temperature, size, and brightness relative to other stars in the Hertzsprung-Russel diagram?
- -massive and brighter than 80% of stars
- -class G
What else does the Hertzsprung-Russel diagram tell us about the lifetimes of stars?
- -how long of a life based on mass
- -what kind of brightness
- -how it will die
- -the stages it will go through
- -how fast it will use up its hydrogen
How do the lifetimes of stars affect the possibility of habitable planets around that star?
- -they affect where the habitable zone is
- -a short lifetime star means that it will be huge and might not be around long enough for life to develop
Which kinds of stars are most likely to have life-bearing planets?
Stars in the category G
What are exoplanets? Why has it taken us so long to find any?
- -exoplanets are planets outside our solar system that orbit a different star
- -it's difficult to detect the movement of stars influenced by planets and a precise method took a long time to be developed
List the 4 most successful methods for exoplanet detection and carefully explain one of more of them.
- -astronomy method
- -transit method
- -direction detection and imaging
- -doppler spectroscopy: studies spectrum to find if a star is moving; appearing as small shifts in wavelengths of spectral lines if they move
How are exoplanets similar to and different from the planets in our own solar system?
- -similar: many like Jupiter with a gaseous composition and massive size
- -different: don't look like Earth and have an eccentric orbit very close to the host star
In your opinion, what are some of the key discoveries made in the subfield of exoplanet detection thus far? (individual planets, groups of planets, detection techniques, new theories, etc.)
-exoplanet Gliese 876 d is a very good candidate for supporting an atmosphere and liquid water
Describe the Drake Equation and explain all the variables used in it. Which of the variables represent whole numbers and which represent fractions?
- -used to calculate the number of radio communicative civilizations (N)
- -Nhp= number of habitable planets
- -flife= fraction of life with interstellar communication
- -fciv= fraction of civilizations in past
- -fnow= fraction of civilizations still in existence
Which of the variables in the Drake Equation can we pin down relatively easily? Which one(s) do we know least about?
We know a lot about the number of habitable planets, but not so much about the fraction of flife and fnow
How likely is it that an average life-bearing planet would give rise to an intelligent species? Make sure you have lots of evidence to back it up.
- -Life is rarely to arise
- -10% – .01%
- -complex evolution
- -complex life arose late on Earth
If an alien species is intelligent, but not technologically-oriented, would we still be able to talk?
Yes through math
What is SETI and what is it's history?
- -Search for ExtraTerrestrial Life
- -started with Russian satellite Sputnik in 1959
- -made Americans curious about other life forms in space
How are SETI and METI different?
SETI listens for messages, METI sends them
What are the characteristics of messages that would show the sender was intelligent? Is there any universal language that we could use of common ground we could find in communicating?
- -strong signal
- -narrow bandwidth
- -mathematical in nature (common ground of communication)
- -Universal language= math!
What are some modern projects involving SETI? Pick one and explain it in detail.
- *-Project Ozma: listened at 1 channel (1420mHz), neutral H (abundant in stars), scanned 400kHz of bandwidth for 1 week
- -National radio astronomy observatory
- -examined Tau Ceti and Epsilon Eidani
- -Drake Equation
- -Allen Telescope array
How long would it take to send a spaceship from our solar system to some of the nearby stars?
closest star: 50 years!
What would it take to keep humans happy and alive if we were to send them to some of the nearby stars?
- -food, water, clothing
- -gravity needed!
Futurists have already imagined some ways in which we might travel between stars. Review some. Which seems most useful once you have weighed such elements as cost, top speed, and human ability to produce this kind of technology.
- -Fission engine: efficient; dangerous and damaging
- -Fusion engine: more powerful that fission; tech doesn't exist
- -Nuclear pulse rocket: A-bomb blows up and propels rocket from the blast, very fast; but it's a nuke!
- -Ramjet engine: fast continuous thrust
- -Ion Engine/Plasma engine: slow, continuous stream; speedy, won't take us to stars
- -Solar sail: can be fast, but weak when far from Sun.
- -Antimatter engine: near light-speed, very expensive
- BEST= Ramjet
What is a Von Neumann Probe and how might we use it to explore space?
a self-replicating probe that can explore worlds, replicate, explore, and repeat that process.
Are there any ways to go faster than the speed of light?
As far as we know, it's not possible because anything faster is breaking the laws of physics and the only thing that can travel that fast is light.
What is the Fermi Paradox?
- -question asked by Enrico Fermi during a conversation with friends.
- -Contradiction over evidence of extraterrestrial life
- -"we're not that special and unique"
What are some possible answers to it?
- -we are truly alone
- -civilizations are common, but they haven't contacted us yet
- -there are civilizations that don't want to contact us because we're too simple for them and aren't ready yet.
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