Reference Article

from Wikipedia, the free encyclopedia

Sunspot

A sunspot is a region on the Sun's surface (photosphere) that is marked by a lower temperature than its surroundings and intense magnetic activity, which inhibits convection, forming areas of low surface temperature.

Although they are blindingly bright at temperatures of roughly 4000-4500 K, the contrast with the surrounding material at some 5700 K leaves them clearly visible as dark spots.

If they were isolated from the surrounding photosphere they would be brighter than an electric arc.

Sunspot numbers have been recorded since 1700 AD and estimated back to 11,000 BP.

The recent trend is upward from 1900 to the 1960s, then somewhat downward.

The Sun was last similarly active over 8,000 years ago.

Note: This article excerpts material from the Wikipedia article "Sunspot", which is released under the GNU Free Documentation License.

See the following related content on ScienceDaily:


Related Stories


Share This



Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins