Exoplanets

Went for my evening walk re-listening to another astronomy lecture on exoplanets or extra solar planets. At this time there are 307 that have been found. Most exoplanets have been discovered using the Radial Velocity or Doppler Method by studying spectral lines and looking for blue and red shifts as the star and its planets orbit around a common center of gravity called a barycenter that create a wobble- a stars blue shift is coming at us, and the red shift is going away. Astronomers need to use computers to sort this out because the shifts are so minuscule. Then Professor Bloom went on to discuss the formations of planets around protostars that form out of the gas and particles of nebulas. By loosing angular momentum these particles fall into the protostar by the effects of gravity that then creates a flat disk. These particles begin to heat, which causes pressure, and depending on the gasses makeup- heavier particles closer to the central mass and lighter particles in farther orbits and their closeness to the central mass determines when a cohesion process starts to bind them to one another. Astronomers have found these protoplanetary disks in other star systems. I think I got this right.