Sculptor Galaxy, discovered by Caroline Herschel [photo: David Attie, Sky at Night magazine]

Drawings, animations, holidays, celebrations of outstanding individuals – all with the Google logo woven into them. If you've used the Google search engine, you've probably noticed the Doodles. I'm glad to see that they include homage to some women in astronomy. Here are four of them.

Caroline Herschel (1750-1848)
A 2016 Doodle celebrated Herschel's 266th birthday. She was the first woman to get credit for discovering a comet, and altogether she discovered eight comets and an assortment of deep sky objects. Her brother William, a musician who'd moved to England from Germany, brought her to England to train her as a singer. When he became an astronomer, he trained Caroline in astronomy too.

For her work as William's assistant, the King of England gave Caroline a salary, making her one of the first women professional astronomers. In addition to her discoveries and her work with William, she published an index to a major astronomical atlas, including correction of errors and making good on omissions in the original. Later work earned her a gold medal from the Royal Astronomical Society.

Maria Mitchell (1818-1899)
Maria Mitchell's Doodle in 2013 celebrated her 195th birthday. Mitchell was the second woman to credited with the discovery of a comet, and receiving a gold medal for her discovery from the King of Denmark enhanced her astronomical reputation.

Caroline Herschel may have been the first woman professional astronomer in England, but Maria Mitchell was the first in the USA. In her late forties she became the professor of astronomy at newly established Vassar College in New York. She could have done astronomical research, but chose to concentrate on the education of young women. Mitchell also traveled widely, and she was acquainted with many prominent scientific and literary figures in America and Europe.

Annie Jump Cannon (1863-1941)
In 2014 a Doodle celebrated Annie Cannon's 151st birthday.

Cannon worked at the Harvard College Observatory, and became a renowned expert on the light spectra of stars. She revised the existing Harvard classification scheme, refining it using a more recent understanding of the physics. With some modification, her system is still in use.

During her working life, Canon classified nearly a quarter of a million stars for the Henry Draper Catalog. Following the death of the director of the observatory, she also oversaw the publication of the Draper catalog.

Overcoming the dual handicap of hearing impairment and being female, Annie Cannon achieved an international reputation. Among the many honors she received was the first honorary doctorate awarded to a woman by Oxford University. When she was 74, Harvard University finally gave her a permanent faculty position.

Beatrice Tinsley (1941-1981)
Unless you're a New Zealander, there's a good chance you haven't heard of Beatrice Tinsley. And since the 2016 Doodle commemorating Beatrice Tinsley's 75th birthday didn't extend to many places, you probably missed that too.

Yet this least-known member of our stunning stellar quartet was the most accomplished. Beatrice Hill was born in England as the bombs of World War II fell, but she grew up in New Zealand, and her astronomical work was done in the USA. She started her career late and died at the age of forty. Nonetheless her work output was prodigious, amounting to around a hundred papers. Some were co-authored, but most of them were written solely by her.

Beatrice was a superb linguist, talented musician, good athlete, and excellent writer. However what really interested her was astrophysics. That wasn't offered at the University of Canterbury in New Zealand, so as an undergraduate she studied mathematics, physics and chemistry, and then completed a master's degree.

She married Brian Tinsley, and they moved to Austin when he was offered a job at the University of Texas. Beatrice was a fish out of water there, since a faculty wife was expected merely to be supportive of her husband's career. They weren't supposed to be academics themselves, be more brilliant than their husbands or want to pursue astrophysics, which wasn't a subject that ladies did in Texas.

She taught herself the basics of astronomy, and was (reluctantly) accepted to do a PhD in Austin. She got top marks in everything and completed the degree in record time. Despite a growing reputation elsewhere, she continued to be ignored by the astronomy department in her own university.

Beatrice Tinsley was one of the great minds of 20th century astronomy. Her radical approach to galaxies and star populations was to consider them in an evolutionary sense. Her pioneering work, using data modeling, helped to lay the foundation for our understanding of galaxies. This in turn is essential to cosmology, because it relates to the origin and the future of the Universe.

By 1975, the year she was employed by Yale University, she had divorced her husband and left Texas. Sadly, in 1978 she was diagnosed with a highly malignant form of cancer. Even that didn't stop her work, which she continued until her death in 1981. Her papers are still cited by astronomers, and the encouragement she gave her students and colleagues is still remembered.