WHAT IS OUR SUN MADE OF? 94 % Hydrogen – the most abundant gas in the universe and 6 % Helium All the other elements make up just 0.13% (with oxygen, carbon, and nitrogen the three most abundant “metals”---they make up 0.11%). In astronomy any atom heavier than Helium is called a metal. If you use the percentage by mass, you find that hydrogen makes up 78.5% of the Sun's mass, helium 19.7%, oxygen 0.86%, carbon 0.4%, iron 0.14%, and the other elements are 0.54%.

How do we know what our sun is made of? SPECTROSCOPY: Spectroscopy uses white light and scatters it using a prism or diffraction grating. When white light passes through heated gases, as in the Sun, it is scattered at different wavelengths. Atoms and molecules can be identified by their signature wavelength numbers or color.

History and study of Spectroscopy "Spectroscopy is the science of using spectral lines to figure out what something is made of. That is how we know the composition of distant stars!" In the 1660's Isaac Newton had shown that sunlight can be separated into separate chromatic (color) components via refraction through a glass prism. (splitting apart white light)

History and study of Spectroscopy In 1817, Joseph von Fraunhofer, independently rediscovered the 'dark lines' in the solar spectrum noticed 15 years earlier by William Hyde Wollaston. Fraunhofer pursued the matter mainly because he saw the possibility of using the lines as wavelength standards to be used to determine the index of refraction of optical glasses. Other physicists, however, were quick to realize that the Fraunhofer lines could be used to infer properties of the solar atmosphere, as similar lines were being observed in the laboratory in the spectrum of white light passing through heated gases. This discovery is what later lead to some of the more important advances in solar physics.

How we use Spectroscopy today: Astronomers commonly refer to stars by their ‘spectral type’ – or color determined by temperature and chemical gas composition of the star. The OBAFGKM classification –O = 28,000K to 50,000K – Blue stars - Hottest –B = 10,000K to 28,000K –A = 7,500K to 10,000K –F = 6,000K to 7,500K – Yellow stars –G = 5,000K to 6,000K (Our Sun) – White star –K = 3,500K to 5,000K –M = 2,500K to 3,500K – Red stars - Coolest

Spectroscopy in Astronomy: today, most information gathered on the Sun and stars is obtained through spectroscopic means.

Layers of the Solar Atmosphere at different wavelengths:

~The Lesson Activity:~ Solar Spectra: A look into temperatures and elements present on the Sun Students will learn to interpret graphs showing emission and absorption lines of atoms in the solar atmosphere. ***Teachers please see entire lesson for: student prerequisites, opening activities, day by day tasks, purpose, objective, assessment, vocabulary list, website links and related lessons. As well as an explanation of an emission and absorption graphs.

Understanding the Graph:

Lab Group Duties: Work Together! Choose one person to be each of the following – (1) Leader (2) Timekeeper (3) Note taker (4) Recorder - description of each in full lesson plan under ‘assessment’.

6/11/ What is expected of you? 1. For you to work together with your group. –One person should NOT be doing all the work! 2. To complete the lab chart and worksheet Each group member must do their own! –(Although only one lab chart needs to be turned in for your group’s grade – each student must fill out the chart to keep in their notes!) 3. Ask questions if you need help!