Exoplanets Flashcards
Describe the three main methods used to find exoplanets.
- Astrometry (When stars wobble, When the exoplanet’s gravity affects them) - Transit method (When exoplanets move across the star the brightness is reduced) - Radial Velocity (Regular Patterns of blueshift and redshift. Because of the attraction between the star and the exoplanet)
What is a “Hot Jupiter?”
Large planets orbiting at extremely close distances to the parent star.
What is the main problem with the current methods used to find exoplanets and why?
We cannot find rocky, Earth-like exoplanets using the current methode: -Because of atmospheric turbulence. -Small mass > smaller effect on host star.
What is the Kepler Spacecraft?
-NASA space observatory -Aims to discover earth sized planets in habitable zone -Transit method > Only instrument is photometer (measures variations in light as planets pass in front of their host star).
What are the problems of using the Transit Method?
We must be in the plane of the exoplanet’s ecliptic to detect changes in light.
What are the two essential chemical ingredients for life?
-Carbon Makes interesting compounds / Organic molecules (“Building blocks” of life) -Liquid water Solvent / Transport Medium / for Photosynthesis / for Hydrolysis / Break down of molecules
Where is water on Earth thought to have come from?
-Deposited by ice containing comets striking Earth. -Out-gassing of Hydrogen and Oxygen from volcanoes.
How do we plan to determine if it is likely that substantial amounts of water were delivered to Earth by comets?
-ESA Rosetta -Launched 2004 -Heading for comet 67p (Churyumov- Cerasimenco) -Ptolemy (one of its instruments: Analyse water content, Check to see what Isotopes are present (are they similar to Isotopes in Earth water?)
What is the habitable zone?
-Narrow range of distances from star -Temperature allows liquid water to exist -Goldilocks Zone (neither to hot or to cold)
Draw a graph to describe how the mass of a star affects the habitable zone.
Who was Frank Drake?
Frank Drake was an American Astronomer Came up with drake equation in 1961
What is the Drake Equation?
The estimated probability of life existing elsewhere in our Galaxy. Also known as Green Bank equation. N = R* fp ne fl fi fc L
List some of the factors considered in the Drake Equation.
-Number of stars in our galaxy -Fraction of stars with planetary systems -Number of planets capable of sustaining life -Fraction of life forms that are intelligent -Fraction of these that can and wish to communicate -Fraction of planet’s lifetime of which such civilisations can live.
Where else in our solar system is life most likely?
Europa (one of Jupiter’s moons)
Name 3 techniques astronomers use to search for signs of life on other planets.
-Space probes. Viking/Curiosity and Mars Huygens and Titan (Saturn’s largest moon) -Spectral analysis of planetary atmospheres of rocky planets. Looking for oxygen, methane etc. -Analysis of radio waves. Intelligent communications.
