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What are the eras, in order, starting from big bang? Describe the characteristics of each.
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Planck. None of our physical laws apply.GUT. Lasts until end of the grand unifiying force.Electroweak. Lasts until end of EW force.Particle. Matter only slightly > Antimatter.Nucleosynthesis. Matter annihilates antimatter and nuclei begin to form. Nuclei. He forms at 3minutes. Universe is too cool for it to blast apart.Atoms. After 300,000 years atoms form and background radiation is released. (radiation can travel).Galaxies. Form after 1 billion years.
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What is CMB?
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Cosmic Microwave Background radiation. From beginning of era of atoms when radiation could move freely now there is this radiation everywhere not caused by anything recent. it was been crazily redshifted due to expansion of universe.
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What's WMAP?
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Wilkinson Microwave Anisotropy Probe. Makes maps of the early universe's anisotropy.
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Explain He-formation during Big Bang? What is the expected ratio by atomic mass and number of moles?
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P + N = PN + gamma rayPN + PN = PNN + PPNN + PN = PNPN + NFor 14 P's you'll get 12 P's and 1 He = 25% Helium and 75% Hydrogen.
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How does inflation explain critical density?
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It pushes everything out like a balloon, making spacetime less curved.
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Why are refracting microscopes not ideal for astronomy?
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They are top heavy, glass has imperfections, and chromatic aberration causes picture to blur. Too sensitive to environment.
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What is angular resolution? Diffraction limit?
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Minimum angular separation that a telescope can distinguish, ultimately caused by interference of light waves. Larger telescopes have better resolution.Diffraction Limit is minimum angle it can resolve, = 2.5E5(w/D)arcsec.
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What three things do astronomers do with telescopes?
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Imaging, spectroscopy, and timing.
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What characteristics define a good place for ground-based observations?
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-high elevation-remote (no light pollution)-not windy-dry (no clouds)
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What are adaptive optics?
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Use rapidly-deformable mirror and reference beam to counteract the bending of light by the atmosphere.
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Why do we put telescopes into space?
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Reduce affect of ground-based weather, reduce turbulence, reduce light pollution, and because only certain types of light (visible and radio) reach the earth's surface.
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What is special about an X-ray telescope? Gamma ray?
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Because X-rays have such small wavelength they tend to go through things. We use telescopes that use glancing angles to focus the beams gently. Gamma rays cant really be bent. so we just sense whether or not they're there.
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What is interferometry?
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Linking multiple telescopes so they act as one huge one.
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What is gravitational equilibrium? How is it maintained?
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Fusion energy maintains pressure outward while gravity provides contracting pressure to counter. If temperature drops fusion slows and gravity increases to drive pressure back up. Temperature increases meaning and increase in fusion and a decrease in gravity, cooling.
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What are the layers of the sun? Briefly describe them.
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Core. Site of fusion. about 15 million K.Radiation Zone. Energy is moved primarily through radiation/photons randomly bouncing around.Convection Zone. Turbulent boiling and falling of plasma to move energy. Photosphere. Surface of convection zone where sunspots occur. about 6000K.Chromosphere. ten's to hundreds of thousands of K. Middle layer of atmosphere.Corona. a million K. outermost layer.Solar Wind. Flow of charged particles from surface.
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