Have you ever been worried about the impact of an asteroid wiping out human life? Well, I have some disturbing news for you: there is another possibility involving the explosion of a massive star that gives rise to a gamma-ray burst (called by astronomers simply a GRB), when the star ends its life producing a black hole.
July 4, 2018 saw the 150th birthday of Henrietta Swan Leavitt (1868 – 1921), one of the most important astronomers of the 20th century. Born in Lancaster, Massachusetts, Leavitt graduated from Radfcliffe College, Harvard, in 1892. She then stayed on at the Harvard College Observatory as a volunteer research assistant. Whilst attempting a graduate degree in astronomy and travelling in Europe, she became ill with grave consequences for her hearing. In 1902, then director, Edward Pickering, invited Henrietta to join the permanent staff at Harvard, where she was assigned to study “variable” stars.