Frequently Asked Questions

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Science Questions Astronomy, General What are the differences between stars, planets, and moons? What kinds of star catalogs are there? Astronomy, Measures How old are the stars? What is Fe/H? What does stellar magnitude (visual, absolute, bolometric) mean? What is the difference between parsec and light year? What do spectral type and luminosity class mean? How big is an Astronomical Unit? What is precession of the equinoxes? How do astronomers measure the position of stars in our night sky? Astrophysics Mass and Gravity What is mass? Mathematics What are logrithms and exponents, and how are they used? Stellar Identities What are the names of the stars? How many star catalogs are there? How can you have more than one star in a system? Where do the ADS catalog numbers come from? Where do the DM catalog numbers come from? What does Flamsteed-Bayer mean? What is the Gliese catalog? Where do the HD catalog numbers come from? Where do the HIP catalog numbers come from? Where do the HR catalog numbers come from? Where do the MSDB catalog numbers come from? Where do the SAO catalog numbers come from?