Class begins with a problem on transits and learning
astronomers obtain through observing them. For example, radii of stars can be estimated. Furthermore, applying the Doppler
shift method, one can find the mass of a star. Finally, a star's density can be calculated. A second method for identifying
planets around stars is introduced: the astrometry method. The method allows for an extremely accurate assessment of a star's precise position
in the sky. Special
features of the astrometry method are discussed and a number of problems are solved.