exoplanets Flashcards
What are exoplanets and why are direct observations difficult?
Planets that are not within our solar system.
Direct observations are difficult as the light is often obscured by the star they orbit.
Also they tend to be too close together for a telescope to resolve them.
Radial velocity method
A star and a planet orbiting their common central mass, meaning that the star will show tiny variations in its distance from earth, shown by tiny red/blue shifts in its spectrum
Transit method
Involves observing the intensity of the light output of a stat.
If a planet crosses in front of a star (‘transits’), the intensity dips slightly.
If the intensity of a star dips regularly, could be a sign that there is an exoplanet orbiting it.
However, this method is limited since it only works if the line of sight to the star is in the plane of the planet’s orbit, which is more likely for planets with small orbits. This is because most orbits are inclined.
