Hi Bianca,

This depends on your definitions of "astronomy" and "chemistry." Some people may define these sciences a lot differently than I do. I would consider someone to be an astronomer if they study distant objects like stars and galaxies using a telescope. Astronomers often use spectroscopy to help them identify the materials in distant stars. Spectroscopy involves understanding the wavelengths of light that can be emitted by different atoms and molecules. Spectroscopy is one area that has some overlap between physics and chemistry - I remember learning about it in both my physics and chemistry classes. While there is some overlap between the different physical sciences, most of the astronomers I know usually don't include much study of topics that I would consider to be chemistry in their research, like understanding chemical reactions and the structure of different molecules.

Chemistry is more important to studying our own solar system, but I would not call someone who studies objects in our solar system an astronomer. The reason is that most of us have different educational backgrounds from astronomers, and we use different kinds of observations in our research. Many of the people who study the Sun and the Earth's magnetosphere have backgrounds in plasma physics. For example, even though I did study astronomy and chemistry in school, most of my work is in plasma physics. People with my kind of educational background often use data from satellites that take local measurements, as opposed to looking at things from far away through a telescope. There are some plasma physicists who study the magnetospheres of other planets as well. However, planetary scientists (people who study the other planets in our solar system) have backgrounds in geology, atmospheric physics, and even chemistry. When you are studying the surfaces of other planets, it is important to learn about the geological features, the chemical compositions of rocks on the planet, the chemical composition of the atmosphere, and how the materials in the atmosphere react chemically with the rocks on the planet. Planetary scientists sometimes use telescope observations, but obtaining measurements from satellites and the surface of the planet (for example, from the Mars rovers) is vital to their work.

If you are interested in space exploration and really like chemistry, you may find planetary science to or geology to be more interesting than astronomy.

Kris