Astronomers used early telescopes to study the sun. Now spacecraft study the star at the center of our solar system.
Transcript:Hello and welcome. I'm Jane Houston Jones at NASA's Jet Propulsion Laboratory in Pasadena, California
2009 is International Year of Astronomy. Each month this year we’ll take you on a tour of one of the best celestial objects on view. This month, it’s our star, the Sun!
Galileo and Englishman Thomas Harriott both observed the sun and sunspots in 1610, but they weren’t the first.
Chinese and Korean astronomers wrote about sunspots almost three thousand years ago. John of Worcester, who was an English monk, made the earliest existing drawing of sunspots in 1128 .
Galileo’s solar observations of 1612 were made at the same time of the day every day, and so the motion of the spots across the Sun can easily be seen. This motion allowed early astronomers to estimate the Sun's rotation period, which is about 27 days.
The early astronomers soon projected the Sun's image through the telescope onto a piece of paper, or through a pinhole projector. This made it possible to study the Sun in detail without damaging their eyes.
Many other astronomers in the 17th century including Scheiner, Gassendi and Hevelius also recorded their solar observations.
More than two dozen past and present NASA missions explored the Sun-Earth System.
The Ulysses spacecraft, which launched in 1990, studied the Sun before, during and after the last solar maximum in 2001. After more than 18 years in flight, Ulysses returned a wealth of data that led to a much broader understanding of the global structure of the Sun's environment.
The TRACE spacecraft launched in 1998, and it studies the magnetic structures which emerge through the photosphere or the visible surface of the Sun.
The Genesis spacecraft collected samples of the solar wind, a stream of charged particles from the Sun. The samples were returned to Earth in 2004 and are now being studied in a special lab at NASA’s Johnson Space Center.
STEREO, which launched in 2006, uses two observatories, one ahead of Earth in its orbit and one behind, to study the structure and evolution of solar storms as they blast from the sun and move out through space.
SOHO, the Solar and Heliospheric Observatory, has been keeping a watch on the sun since 1996. It can warn the Earth of approaching coronal mass ejections that could disrupt communications.
Never look directly at the sun or you might damage your eyes. Contact your local amateur astronomy club and join them for safe solar observing.
And remember to view Saturn this month. The rings offer a different view. They almost appear to be edge-on.
You can read all about the Sun on NASA's IYA website
And you can learn all about NASA's missions at
Thanks to the following for submitting images: Jane Houston Jones, Morris Jones, Pete Goldie, Sarah Szczechowicz Goldie.
That's all for this month. I'm Jane Houston Jones.