Topic 8 How To Find Life On Exoplanets Flashcards
(10 cards)
How can we determine if a planet has a biosphere?
- we could perform direct sampling and imaging at its surface. Unfortunately, this is more than a century off.
- we can analyse the electromagnetic radiation that we receive from the planet. 
What can the infrared spectrum from a planet reveal?
-The planets surface temperature if we can see to the surface and if not atmospheric temperature.
-The atmospheric composition.
If water vapour and CO2 are found and its surface temperature is within the range for liquid water and complex carbon compounds then the conditions would probably be suitable for carbon liquid water surface life.
What would be indicated by strong ozone absorption lines?
Strong absorption lines of 03 would suggest that there are considerable quantities of oxygen (O2), such as could be sustained readily by oxygenic photosynthesis.
If the planet has long been geologically inactive then oxygen can be produced by the photolysis of water. this could create an environment which appears to be supporting life that is actually not supporting life.
What would be considered strong evidence for life on an exoplanet?
Stronger evidence of a biosphere would be provided by redux pairs far from their chemical equilibrium with each other such as O2 (as indicated by 03) and CH4 in the earths atmosphere.
Would the detection of oxygen be required for life?
Lack of abundant oxygen in the atmosphere would not necessarily imply absence of a biosphere. Alien biology may be able to use other elements to perform bodily functions such as sulphur.
Can visible light spectrum be used to search for life?
The Visible and near infrared spectrum of an EXOplanet might also reveal habitability or a biosphere by detecting atmospheric gases or the effects associated with chlorophyll and other biological substances, or the variability of the light curve
What can be detected in the visible light spectrum that cannot be detected in the infrared spectrum? .
Molecular oxygen has strong absorption lines in the visible light spectrum however is not detectable in the infrared spectrum.
How can we measure the spectra from exoplanets?
When an XO planet transits across it star we can subtract the stars of Spectra leaving behind the light that has passed through the planets atmosphere at the edge of the planetary disc. This requires a telescope with a very high spectral resolution.
These planets are commonly gas giant and it is increasingly difficult to do on terrestrial planets.
What is the difference between an absorbent spectrum and reflective spectrum?
An absorption spectrum is what is detected in the infrared as part of the spectrum when light passes through your planets atmosphere and certain wavelengths are absorbed.
A reflective spectrum is when visible light is reflected by a planet showing what wavelengths were absorbed in the visible spectrum.
Why are interstellar probes unlikely any time soon?
Due to fast distances it would take a probe approximately 40 years to reach our nearest star system Proxima century at 10% the speed of light. This does not count for acceleration and the deacceleration times which would make the journey even longer.
