Solar minimumSolar minimum is the regular period of least solar activity in the Sun's 11-year solar cycle. During solar minimum, sunspot and solar flare activity diminishes, and often does not occur for days at a time. On average, the solar cycle takes about 11 years to go from one solar minimum to the next, with duration observed varying from 9 to 14 years.
Solar maximumSolar maximum is the regular period of greatest solar activity during the Sun's 11-year solar cycle. During solar maximum, large numbers of sunspots appear, and the solar irradiance output grows by about 0.07%. On average, the solar cycle takes about 11 years to go from one solar maximum to the next, with duration observed varying from 9 to 14 years. Large solar storms often occur during solar maximum.
Coronal loopIn solar physics, a coronal loop is an ill-defined arch-like structure in the Sun's atmosphere made up of relatively dense plasma confined and isolated from the surrounding medium by magnetic flux tubes. Coronal loops begin and end at two footpoints on the photosphere and project into the transition region and lower corona. They typically form and dissipate over periods of seconds to days and may span anywhere from 1 to 1,000 megametres (621 to 621,000 mi) in length.
SunspotSunspots are temporary spots on the Sun's surface that are darker than the surrounding area. They are regions of reduced surface temperature caused by concentrations of magnetic flux that inhibit convection. Sunspots appear within active regions, usually in pairs of opposite magnetic polarity. Their number varies according to the approximately 11-year solar cycle.
Modern MaximumThe Modern Maximum was found by Sami Solanki, Ilya G. Usoskin and colleagues as the period of unusually high solar activity which began with solar cycle 15 in 1914. It reached a maximum in solar cycle 19 during the late 1950s and may have ended with the peak of solar cycle 23 in 2000, as solar cycle 24 is recording, at best, very muted solar activity. Another proposed end date for the maximum is 2007, with the decline phase of Cycle 23.
PhotosphereThe photosphere is a star's outer shell from which light is radiated. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately 2⁄3, or equivalently, a depth from which 50% of light will escape without being scattered. Stars, except perhaps neutron stars, have no solid or liquid surface. Therefore, the photosphere is typically used to describe the Sun's or another star's visual surface.
Solar flareA solar flare is a relatively intense, localized emission of electromagnetic radiation in the Sun's atmosphere. Flares occur in active regions and are often, but not always, accompanied by coronal mass ejections, solar particle events, and other eruptive solar phenomena. The occurrence of solar flares varies with the 11-year solar cycle.
SunStar at the centre of the Solar SystemThe Sun is the star located at the centre of the Solar System. It is a massive sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light and infrared radiation with 10% at ultraviolet energies. It is the main source of energy for life on Earth.
AuroraAn aurora (pl.aurorae or auroras) is a natural light display in Earth's upper atmosphere caused by charged particles from the Sun colliding with atoms in the atmosphere. These collisions excite oxygen and nitrogen, which then emit light of different colours such as green, red, and purple. When observed in high-latitude regions they are called polar lights and aurora polaris.
SunlightLight emitted by the SunThe Sun, as seen from low Earth orbit overlooking the International Space Station. This sunlight is not filtered by the lower atmosphere, which blocks much of the solar spectrum.Sunlight shining upon two different sides of the U.S. state of New Jersey. Sunrise on the Jersey Shore at Spring Lake, Monmouth County (above), and sunset on the Shore at Sunset Beach, Cape May County (below).
Outer spaceVoid between celestial bodiesFor other uses, see Outer space (other).Being essentially empty, outer space allows the earliest (redder) galaxies to be viewed without obstruction, as in the Webb's First Deep Field image.Outer space, or simply space, is the expanse that exists beyond Earth's atmosphere and between celestial bodies.
Periodic functionA periodic function is a function that repeats its values at regular intervals. For example, the trigonometric functions, which are used to describe waves and other repeating phenomena, are periodic. Many aspects of the natural world have periodic behavior, such as the phases of the Moon, the swinging of a pendulum, and the beating of a heart. The length of the interval over which a periodic function repeats is called its period.*As an Amazon Associate I earn from qualifying purchases.