Measuring the Universe – 150th birthday of Henrietta Swan Leavitt

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.

Hubble sees a messy Messier

About 100 000 light years across, Messier 66 is the largest galaxy in the “Leo Triplet”, three interacting spiral galaxies about 33 million light years from us. This new Hubble Space Telescope image shows that M66 seems to have been through the mangle. Misshapen with an off-centre core, the galaxy is not a neat spiral. It has been tugged by the gravitational pulls of its neighbours’, NGC 3628 and M65, and indeed may have suffered a close encounter with NGC 3628 a billion years or so ago which ripped away hundreds of thousands of stars.

Located just under the line between Regulus and Denebola, M66 and M65 can be seen with a small telescope or 10×50 binoculars in the spring. Why not go out to see if you can find these distant islands of stars?

(What is a Messier object? You can find out in this issue of Astronotes)