- Beta Doradus (stars.astro.illinois.edu)
BETA DOR (Beta Doradus). Among the most important of all stars are the Cepheid variables, named after the prototype, Delta Cephei. Many of them dot the naked- eye starry sky, their number including Eta Aquilae, Zeta Geminorum (Mekbuda), even Polaris, the brightest of them (though Polaris’s variations are too small to be witnessed by eye). Here is another bright one, fourth magnitude (averaging 3.76) Beta Doradus, the second brightest star (after Alpha) in the modern southern constellation Dorado, the Swordfish.
- Chlorine (Wikipedia)
Chlorine is a chemical element; it has symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity on the revised Pauling scale, behind only oxygen and fluorine.