Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2003 October 25
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

Islands in the Photosphere
Credit & Copyright: Gunther Groenez

Explanation: Awash in a sea of plasma and anchored in magnetic fields, sunspots are planet-sized, dark islands in the solar photosphere, the bright surface of the Sun. Before the enlightened(!) age of cameras, solar observers created detailed drawings of sunspots as they changed and progressed across the visible solar disk. But contemporary observers also regularly use this time-honored method of monitoring sunspots. In this sketch from March 6th 2001, astronomer Gunther Groenez has faithfully recorded the intriguing shapes and shades of major visible sunspot groups and labeled them according to their NOAA active region number. Solar north is up and east to the right. Groenez' technical equipment includes H and 2H pencil leads for the sunspot umbra (dark) and penumbra (light) areas respectively. Want to draw sunspots too? Now's your chance as two large sunspot groups are presently making their way across the solar disk. Activity associated with these large sunspots may trigger aurora in the coming days.

Tomorrow's picture: Three Monsters

< | Archive | Index | Search | Calendar | Glossary | Education | About APOD | >

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.