Although wives are often remembered as the helpmates of their husbands, sisters are less likely to be given that spotlight. Most male scientists have probably had sisters, but astronomers seem to be the only ones who made their sisters part of their team. Caroline Herschel, for example, helped her brother William Herschel with his observations for many years and was known and honored as a discoverer of planets.

Two centuries before Caroline Herschel made her mark, another younger sister became an important assistant to her astronomer brother. Born in 1556 (or perhaps 1559) Sophia Brahe was the youngest child in a large brood of children born to a noble family in Denmark. Her brother, Tycho Brahe, the oldest child in the family, was ten years older than Sophia. As she grew up, Tycho realized that his youngest sister was unusually curious and loved to learn, so he provided books to help her learn about chemistry and horticulture. He believed that a woman would be unable to become an astronomer so he did not suggest that she learn about heavenly bodies even though that was his major interest. But Sophia was a determined girl. She read astronomy books in German and had Latin books translated so she could study them. Eventually Tycho recognized his sister’s talents and began to make her one of his assistants.

Sophia frequently visited Tycho’s observatory, Uranienborg. Tycho Brahe was the first astronomer to recognize the importance of careful, precise observations of the stars and planets. Sophia Brahe helped him to prepare his observations for his publication De nova stella, or On the New Star. She assisted with a set of observations that led to the discovery of the supernova now called SN 1572, as well as observations of the December 8, 1573 lunar eclipse. She, along with other assistants, made observations that helped Tycho develop his theory of orbits. This work was essential in establishing modern methods to predict the positions of planet.

Today, as we look back on the work of Brahe and his associates, it is hard to believe they could learn so much about the behavior of astronomical bodies without the help of modern instruments like the telescope. It was not until thirty years after Brahe’s observations that a Dutchman, Hans Lippershey, applied for the first patent for a telescope.

Astronomy was only one part of Sophia’s life. In 1579, she married Otto Thott. The couple had one son before Otto died leaving Sophia to raise the son and maintain Thott’s estate until the child came of age. She continued to visit her brother at Urainienborg, but also used her horticultural expertise to design magnificent gardens and develop her son’s estate.

Like most astronomers of the time, both Tycho and Sophia were interested in astrology. Most people believed that accurate predictions about people’s lives could be based on the movements of planets. The desire for astrological predictions was one of the most important reasons why many rulers supported astronomers in their courts. Tycho was more interested in learning about astronomy, but Sophia Brahe devoted much of her time to investigating genealogy and astrology.

In 1602, Sophia Brahe married Erik Lange, an alchemist who devoted much of his fortune into trying to change base metals into gold. Her family, except for Tycho, strongly disapproved of the marriage of Lange and Sophia, so the couple lived in poverty for many years. But her work continued. Besides her studies in astronomy and astrology, Sophia Brahe completed a detailed genealogy of the Danish Royal Family

According to an article in Wikipedia, the poet Johan L. Heiberg proclaimed that “Denmark must never forget the noble woman who, in spirit much more than flesh and blood, was Tycho Brahe’s sister; the shining star in our Danish heaven is indeed a double one.”