Alex Filippenko
66) Understanding the Universe: An Introduction to Astronomy, 2nd Edition: Our Sun's Brilliant Future
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As it gradually uses up the hydrogen in its core, fusing it to helium, the Sun will expand to form a red giant star. Through a series of relatively nonviolent eruptions, it will expel its outer layers of gas, producing a beautiful, glowing nebula around the dying core.
67) Understanding the Universe: An Introduction to Astronomy, 2nd Edition: Light-The Supreme Informant
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Astronomers obtain most of their information through the analysis of light. This lecture introduces the electromagnetic spectrum and the technique of spectroscopy, in which light is dispersed into its component colors, as in a rainbow.
70) Understanding the Universe: An Introduction to Astronomy, 2nd Edition: The Fingerprints of Atoms
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Electrons jumping between different energy levels in atoms emit and absorb photons in a characteristic way for each element. Thus, astronomers can use the light from distant objects to deduce their chemical compositions.
75) Understanding the Universe: An Introduction to Astronomy, 2nd Edition: Active Galaxies and Quasars
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The central regions of many galaxies go through an active, very luminous phase early in their development. The most powerful of these active galaxies, called quasars, shine like beacons across billions of light years of space.
76) Understanding the Universe: An Introduction to Astronomy, 2nd Edition: Asteroids and Dwarf Planets
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Under a new definition adopted in 2006, planets are more narrowly defined and a new class called dwarf planets has been created, which includes Pluto, Eris (a Kuiper-belt object larger than Pluto), and Ceres (the largest asteroid).
79) Understanding the Universe: An Introduction to Astronomy, 2nd Edition: Enigmatic Gamma-Ray Bursts
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Roughly once per day, somewhere in the sky, there is a short, intense burst of gamma rays. Most of these events originate in very distant galaxies, making them among the most powerful explosions in the Universe-but they are not evaporating black holes.