Sunspots
Sunspots are areas on the sun's surface that are colder than the rest of the sun's surface. Since they are colder, they appear darker. Scientists look at sunspots by projecting a picture of the sun onto a blank surface. Sunspots often come in clusters and some are huge. The diameter of some sunspots is greater than Earth's. They develop in a few days and last for a few weeks or sometimes for a few months.
The Discovery of Sunspots
Scientists have studied sunspots since the early 1600s. One of the earliest to study them was Galileo. He invented the telescope to observe the stars. He was one of the first scientists to deduce that sunspots were actually a characteristic of the sun rather than shadows of planets between the sun and Earth.
In the 1800s, scientists discovered that sunspots appear in cycles. The number of sunspots tends to rise and fall over a period of about 11 years.In 1848, Rudolph Wolf began to count sunspots on the face of the sun. He found more sunspots during the middle of the cycle, called the "solar maximum." During the "solar minimum," which is at the beginning and end of the cycle, there are fewer sunspots.
Earth and the Solar Cycle
How do sunspots affect Earth? Scientists don't have all of the answers, but they have made some interesting observations. From 1645 to 1715, there were far fewer sunspots. At this same time, Earth was very cold. In fact, meteorologists call this period in time the "Little Ice Age."
Scientists around the world, including those at NASA (National Aeronautics and Space Administration), track sunspot activity. An increase in sunspot activity indicates an increase in other solar activity, including solar flares. Solar flares are giant explosions on the sun. These flares bombard Earth with tiny energetic particles. Earth's atmosphere protects us from most of these particles. Still, some of the particles break through. They can disrupt radio and electric signals.
1
Select the correct answer.
Which of these could be caused by an increase in sunspots activity?
A.
A stalled car
B.
A drop in Earth's temperature
C.
A power failure
