Welcome to the Stars

Are all stars like the Sun?

The answer to this basic question has driven the field of astronomy and astrophysics for nearly 100 years.

Explore the answer here by observing stars and comparing their features to those of the Sun - by classifying stars. Your participation will be a major contribution, observing stars never before classified. You can be the very first person to measure the temperature of a star never before measured! This is discovery in the purest sense of the word.

  • To explore with us, click on To Take Part.
  • Learn more about stars, spectroscopy, and the data in this project by clicking on The Science.
  • If you have any questions, please do not hesitate to contact us.  We are very interested in your comments.

We hope you enjoy your visit and decide to work with the astronomers at the Astronomical Photographic Data Archive (APDA) at the Pisgah Astronomical Research Institute (PARI).

APDA is a collection of astronomical photographic plates taken over a period of nearly 100 years and safely archived at PARI.  Roughly 33,000 of the plates contain information on the spectra of more than 1,000,000 stars (estimated).  The plates were taken by generations of astronomers at many of the major observatories in the world.  You can join this group of astronomers and explore the stars!

The Sun

The Sun

  • Surface Temperature: 6,000 C
  • Composition: 73% Hydrogen and 25% Helium and 1.6% other by mass
  • Diameter (photosphere): 1,391,980 km
  • Mass: 1.99 x 1033 g
  • Average Density: 1.41 g/cm3
  • Luminosity: 3.83 x 1033 erg/sec
  • Rotation Period: 25 days (equator)
The Sun's Spectrum

"Beyond the stars of the sixth magnitude you will behold through the telescope a host of other stars, which escape the unassisted sight, so numerous as to be almost beyond belief, for you may see there more than six other differences of magnitude, and the largest of these, which I may call stars of the seventh magnitude, or of the first magnitude of invisible stars, appear with the aid of the telescope larger and brighter than stars of the second magnitude seen with the unassisted sight."

-Galileo Galilei. in Sidereus Nuncius. March 1610.