Topic 2.4 - Exoplanets Flashcards
Who discovered the first exoplanet?
Michael Mayor and Didier Queloz of the Observatoire de Genève
When was the first exoplanet discovered?
1995
What are the 3 main techniques for detecting or inferring exoplanets?
- Astrometry
- Transit method
- Radial velocity method (using Doppler shifts)
What is astrometry?
Measuring the precise position of the stars relative to each other, if they wobble it’s likely they have an exoplanet
What is transit method?
Measuring of dips in light of stars to see if a planet has moved in front of it.
What is Radial velocity method (using Doppler shifts)?
The wobbling of a star did to exoplanets gravity can also cause wavelengths to be slightly red-shifted and blue-shifted on a regular time scale as a star moved away from us and towards us Spectroscopy is able to reveal small shifts in wavelength and has been proved the most successful
What limits the accuracy of astrometry?
The turbulence of our atmosphere
What is the problem with the Transit method?
It has to be on the same plane as we are in order to see it moving across
Why can’t rocky planets similar to Earth be found using these methods?
The atmospheric turbulence and the fact that planets with a relatively small mass have less significant effect on their host star
What are the two essential chemical ingredients for life?
Carbon and liquid water
Why is carbon an essential chemical ingredient for life?
It has the ability to make interesting compounds that form the basis of more complex organic molecules, the chemical ‘building blocks’ of life
Why is liquid water an essential chemical ingredient for life?
It is an excellent solvent and transport mechanism for many nutrients, necessary for photosynthesis and essential for breaking down large molecules into smaller ones
What are the two principal origins of water?
- Outgassing of hydrogen and oxygen from volcanoes that combined to produce steam which condensed into water
- It was deposited by comets (containing ice) striking Earth
Why is it easy to see that earth is the most likely planet in our solar system to sustain life?
Mercury and Venus are too hot and Mars and the outer planets are too cold
What is the habitable zone?
A narrow range of distances from the star in which the temperature allows liquid water to exist (sometimes called the Goldilocks zone because it is ‘neither too hot nor too cold’).
Who made the Drake equation and when?
Frank Drake in 1961
What is the Drake Equation?
Combine estimated probabilities of a number of factors That as a result estimate number of civilisations in our galaxy that could communicate with us
Name 3 factors of the Drake Equation?
N- number of civilisations where communication is possible
R*- average rate of star formation per year in our galaxy
L- length of time signals released into space
Name two candidates in our solar system that might possess the correct ingredients for life to exist.
Mars and Jupiters moon Europa
Name 3 techniques used by astronomers to search for sings of life of other planets.
- Space probes
- Spectral analysis of planetary atmosphere
- Analysis of radio waves from space
How do we use space probes to search for signs of life?
Test for microbes or bi-products
How does spectral analysis of planetary atmospheres test for life?
Search for gases such as oxygen and methane that are produced by living organisms
How does the analysis of radio waves help search for life?
Try to detect signals that could have originated from extra terrestrial intelligent forms of life in Galaxy
What are the potential dangers of finding life on other planets?
- Would it be wise to transfer organisms form one environment into a completely different one in which they might become extinct or adapt too well and flourish
- We know nothing of the intent or capabilities of the possible alien life-forms so life on Earth could be threatened
