- Ocean Beach is a beach on the west coast of San Francisco, California, United States, bordering the Pacific Ocean. It is adjacent to Golden Gate Park, the Richmond District, and the Sunset District. The Great Highway runs alongside the beach, and the Cliff House and the site of the former Sutro Baths sit at the northern end. The beach is a part of the Golden Gate National Recreation Area, which is administered by the National Park Service.
- Stellar classification (Wikipedia)
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The spectral class of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere’s temperature.