how are we able to see planets that are 100’s of lightyears away? By continually increasing the magnification of a telescope? How do we know anything about the planets atmosphere if it’s that far away? For example, the Corot-7b, we are told it rains rocks there.
In: Technology
The most common method is by watching the host star’s output for telltale signs of variation in it’s brightness and position. A star that wobbles a small fraction tells you that there is some other body’s gravity acting on it. This is done by watching a star’s spectral lines as they change because a star and it’s planet(s) will orbit a common center of mass. A star that moves away from you will have it’s spectral lines shift red, and then blue as it comes toward you.
Additionally if a star dims a small fraction on a periodic basis, then that means an orbital body has moved across it from our perspective.
The size and mass of a star is determined first by watching binary stars. If you determine the size of their orbits around each other and the period (speed) of their orbits, then you can calculate their respective mass as well. Once you know the mass of a pair of binary stars you can apply that knowledge to similar stars not in binary systems. (And the more binary systems you study, the larger the range of single stars you can size)
Once you know the size of the individual star, you can calculate the mass of the orbital body and it’s orbit by the parents star wobble and changes in luminosity.
What the planet is made up of can be seen in general terms from watching the transmission spectrum coming from the system, and the spectral lines will tell you what materials are present.
Latest Answers