## Astrophysics Formulas and Astronomy Formulas

Welcome to *Astrophysics Formulas*. Here you will find astrophysics formulas and astronomy formulas presented in a way that is more than just a bunch of equations. The idea is to provide *practical* forms as far as possible. Forms that are *directly* useful and that foster developing intuition for the nature of the relations represented by the equations, and for the underlying physics. Choose *Astrophysics Formulas* from the menu or this link, or use the search box in the right-hand sidebar.

Use the button or link above to access a free pdf download containing an extended summary of astrophysics formulas which we hope will be a useful off-line quick reference (even though the pdf has more than 50 pages). The website entries have more detail and more explanation than the entries in the pdf file, but currently the pdf file is ahead of the website entries in the number of entries. Please check back soon for updates. If you sign up to the mailing list in the right-hand sidebar you will be informed when substantial new material has been added to the site.

*Tip* on unit conversions: Google is pretty clever and typing even some of the most obscure unit conversion questions into a Google search box will give you something sensible. However, there are some particular things that are not handled very well and these will be handled in *astrophysics formulas* (for example, keV to Kelvin, meV to kg, etc.).