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The second half of the course begins, focusing on black holes and relativity. In introducing black holes, Professor Bailyn offers a definition, talks about how their existence is detected, and explains why (unlike in the case with exoplanets where Newtonian physics was applied) Einstein’s Theory of Relativity is now required when studying black holes. The concepts of escape and circular velocity are introduced. A number of problems are worked out and students learn how to calculate an object’s escape velocity. A historical overview is offered of our understanding and discovery of black holes in the context of stellar evolution.

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Class begins with a problem on transits and learning what information 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. A short summary is given on the three methods astronomers use to identify exoplanets. Class ends with an overview of upcoming space missions and the hope of detecting the presence of biological activity on other planet.

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The class begins with a discussion on transits – important astronomical events that help astronomers to find new planets. The event occurs when a celestial body moves across the face of the star it revolves around and blocks some of its light. By calculating the amount of light that is being obscured astronomers can obtain important information about both star and planet, such as size, density, radial velocity and more. The concept of planetary migration is explained in order to better understand the dramatic differences between bodies in the Inner and Outer Solar System. Finally, potential problems in the Solar System that may occur as a result of migration are addressed.

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Professor Bailyn talks about student responses for a paper assignment on the controversy over Pluto. The central question is whether the popular debate is indeed a “scientific controversy.” A number of scientific “fables” are discussed and a moral is associated with each: the demotion of Pluto (moral: science can be affected by culture); the discovery of 51 Peg b (morals: expect the unexpected, and look at your data); the disproof of pulsation as explanation for the Velocity Curves (moral: sometimes science works like science).

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The formation of planets is discussed with a special emphasis on the bodies in the Solar System. Planetary differences between the celestial bodies in the Inner and Outer Solar System are observed. Professor Bailyn explains how the outlook of our Solar System can predict what other star systems may look like. It is demonstrated how momentum equations are applied in astronomers’ search for exoplanets. Planet velocities are discussed and compared in relation to a planet’s mass. Finally, the Doppler shift is introduced and students learn how it is used to measure the velocity of distant objects, such as galaxies and planets.