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The Sunspot Number (SSN) is the number of sunspots on the Sun's photosphere in visible light on the side of the Sun visible to an Earth observer. The number and total area of sunspots are related to the brightness of the Sun in the EUV and X-ray portions of the solar spectrum and to solar activity such as solar flares and coronal mass ejections.
However, the Sun also produces streams of high energy particles known as the solar wind, and radiation that can harm life or alter its evolution. Under the protective shield of Earth's magnetic field and its atmosphere, Earth can be seen as an island in the universe where life has developed and flourished. [6] [7]
In astronomy, coordinate systems are used for specifying positions of celestial objects (satellites, planets, stars, galaxies, etc.) relative to a given reference frame, based on physical reference points available to a situated observer (e.g. the true horizon and north to an observer on Earth's surface). [1]
Meteorology (Greek: Μετεωρολογικά; Latin: Meteorologica or Meteora) is a treatise by Aristotle. The text discusses what Aristotle believed to have been all the affections common to air and water, and the kinds and parts of the Earth and the affections of its parts.
Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not begin until the 18th century. The 19th century saw modest progress in the field after weather ...
For an observer on the ground, the amount of the arc that is visible depends on the height of the sun above the horizon. It is a full semicircle with an angular radius of 42° when the sun is at the horizon. But as the sun rises in the sky, the arc grows smaller and ceases to be visible when the sun is more than 42° above the horizon.
The Sun has also undergone periodic changes in luminosity that can have a significant impact on the Earth. [108] The Maunder minimum, for example, is believed to have caused the Little Ice Age phenomenon during the Middle Ages. [109] At the center of the Sun is the core region, a volume of sufficient temperature and pressure for nuclear fusion ...
Astronomy – studies the universe beyond Earth, including its formation and development, and the evolution, physics, chemistry, meteorology, and motion of celestial objects (such as galaxies, planets, etc.) and phenomena that originate outside the atmosphere of Earth (such as the cosmic background radiation).