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In solar physics, a spicule, also known as a fibril or mottle, [a] is a dynamic jet of plasma in the Sun's chromosphere about 300 km in diameter. [1] They move upwards with speeds between 15 and 110 km/s from the photosphere and last a few minutes each [ 1 ] before falling back to the solar atmosphere. [ 2 ]
The Sun is classed as a G2 star, [66] meaning it is a G-type star, with 2 indicating its surface temperature is in the second range of the G class. The solar constant is the amount of power that the Sun deposits per unit area that is directly exposed to sunlight.
From 2007 to 2009, sunspot levels were far below average. In 2008, the Sun was spot-free 73 percent of the time, extreme even for a solar minimum. Only 1913 was more pronounced, with no sunspots for 85 percent of that year. The Sun continued to languish through mid-December 2009, when the largest group of sunspots to emerge for several years ...
NASA defines [2] heliophysics as "(1) the comprehensive new term for the science of the Sun - Solar System Connection, (2) the exploration, discovery, and understanding of Earth's space environment, and (3) the system science that unites all of the linked phenomena in the region of the cosmos influenced by a star like our Sun."
Under this scenario, they claimed the Sun might have contributed 50% of the observed global warming since 1900. [49] Stott et al. estimated that the residual effects of the prolonged high solar activity during the last 30 years account for between 16% and 36% of warming from 1950 to 1999. [50]
Sunspots themselves, in terms of the magnitude of their radiant-energy deficit, have a weak effect on solar flux. [39] The total effect of sunspots and other magnetic processes in the solar photosphere is an increase of roughly 0.1% in brightness of the Sun in comparison with its brightness at the solar-minimum level.
In the long term, the greatest changes in the Solar System will come from changes in the Sun itself as it ages. As the Sun burns through its hydrogen fuel supply, it gets hotter and burns the remaining fuel even faster. As a result, the Sun is growing brighter at a rate of ten percent every 1.1 billion years. [117]
Thus 4 minutes (more precisely 3 minutes, 56 seconds), in the equation of time, are represented by the same distance as 1° in the declination, since Earth rotates at a mean speed of 1° every 4 minutes, relative to the Sun. An analemma is drawn as it would be seen in the sky by an observer looking upward.