That's like asking what is my favorite dessert - there are so many good choices!

While I definitely admire scientists that have done great things, made great discoveries (Marie Curie comes to mind, of course), I also really admire those that have done amazing things in either unusual conditions or non-optimal ones. For instance in my field Marcia Neugebauer was involved in essentially discovering the solar wind - despite not having a PhD and starting off as a fairly junior scientist at JPL. She made huge contributions to the field, including during periods where there were almost no women in the field.
Similarly Peggy Shea - who was told she should drop out of school and stop getting her masters degree because she was a woman. Her original masters project was even taken away from her and given to another student because he was male and expected to continue on in the field. Despite this and many other experiences with sexism, Peggy has continued to make impressive contributions to the fields of energetic particles and space weather.

Christina has some great names in her response, and I have to agree that there are so many great ones to choose from. I still greatly admire Carl Sagan though because he made the Universe so accessible to everyone. That is certainly something I strive for and is indeed the purpose of this forum! :)

Hi Brittani!

In the field of planetary science, Margaret Kivelson who was at UCLA before she retired, is a very important scientist. She is one of the people who helped discover that Jupiter's moon Ganymede has an internal magnetic field, just like Earth does. She also helped show that Jupiter's moon Europa has an ocean under the ice. You can read more about her here: https://en.wikipedia.org/...Margaret_G._Kivelson