Sunspots are dark because they are much cooler than the surrounding portions of the sun, according to Cool Cosmos, a joint project by the National Aeronautic and Space Administration’s Jet Propulsion Laboratory and California Institute of Technology’s Infrared Processing and Analyses Center. These sunspots usually have temperatures of approximately 6,300 degrees Fahrenheit, while the surrounding portions of the sun are approximately 10,000 degrees Fahrenheit.Know More
As explained on SpaceWeather.com, scientists count and catalog these planet-sized cool spots. According to the Marshall Space Flight Center, the abundance of sunspots varies in time. During the late 17th century and early 18th century, sunspot activity was very low. Concurrently, with this reduction in solar spot frequency, the Earth’s temperature dropped significantly. This period is often referred to as the “little ice age,” as many rivers and snowfields remained frozen longer than normal. There is some evidence that similar cool periods occurred in the more distant past as well.
According to Windows to the Universe from the National Earth Science Teachers Association, the sun’s magnetic field causes the sunspots. Once formed, the sunspots may last as briefly as a few hours or as long as a few months. Sunspots typically fluctuate through an 11-year cycle. Even though sunspots appear dark against the surface of the sun, the areas are still almost as bright as the full moon, and if moved away from the sun, they would be luminous.Learn more about Stellar Astronomy
Most stars cannot be seen during daylight hours because light from the sun is brighter than the relatively faint light from the other stars. This is largely a result of the Earth's atmosphere scattering the sun's light so that every point in the sky seems brighter than distant stars.Full Answer >
Auroras are formed when charged particles that are emitted from the sun hit the Earth's magnetic field and the atoms in the atmosphere. This interaction causes the gases in the atmosphere to give out photons of different energies, which can be seen from Earth as light.Full Answer >
The two types of stars that end with supernovae are white dwarfs and massive stars that are at least eight times the mass of the sun. Each of these types of stars undergoes a thermonuclear reaction at the end of its life.Full Answer >
Sirius, commonly referred to as the "dog star" is said to be twice as massive as the sun, with a diameter of 1.5 million miles. Its comparatively tiny companion star, called Sirius B, is only 98 percent of the sun's mass, with a diameter of 7,500 miles.Full Answer >