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’).
