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For example, with an axial tilt is 23°, and at a latitude of 45°, then the summer's peak sun angle is 68° (giving sin(68°) = 93% insolation at the surface), while winter's least sun angle is 22° (giving sin(22°) = 37% insolation at the surface). Thus, the greater the axial tilt, the stronger the seasons' variations at a given latitude.
Ulysses's observations of solar wind speed as a function of helio latitude during solar minimum. Slow wind (≈ 400 km/s) is confined to the equatorial regions, while fast wind (≈ 750 km/s) is seen over the poles. [1] Red/blue colors show outward/inward polarities of the heliospheric magnetic field. An illustration of the structure of the Sun
The heliosphere, the tenuous outermost atmosphere of the Sun, is filled with solar wind plasma and is defined to begin at the distance where the flow of the solar wind becomes superalfvénic—that is, where the flow becomes faster than the speed of Alfvén waves, [87] at approximately 20 solar radii (0.1 AU). Turbulence and dynamic forces in ...
The slow solar wind has a velocity of about 400 kilometres per second (250 mi/s), a temperature of 2 × 10 5 K and a composition that is a close match to the corona. The fast solar wind has a typical velocity of 750 km/s, a temperature of 8 × 10 5 K and nearly matches the photosphere's.
The solar wind plasma which is moving roughly "upstream" (in the same direction as the Sun's motion through the galaxy) is compressed into a nearly-spherical form, whereas the plasma moving "downstream" (opposite the Sun's motion) flows out for a much greater distance before giving way to the ISM, defining the long, trailing shape of the heliotail.
Researchers were unsure exactly where the Alfvén critical surface of the Sun lay. Based on remote images of the corona, estimates had put it somewhere between 10 and 20 solar radii from the surface of the Sun. [5] On April 28, 2021, during its eighth flyby of the Sun, NASA's Parker Solar Probe (PSP) encountered the specific magnetic and particle conditions at 18.8 solar radii that indicated ...
The Sun rotates slowly enough that a spherical, non-rotating model is close enough to reality for deriving the rotational kernels. Helioseismology has shown that the Sun has a rotation profile with several features: [47] a rigidly-rotating radiative (i.e. non-convective) zone, though the rotation rate of the inner core is not well known;
The Sun' light influences all life and processes on Earth; it is an energy provider that allows and sustains life on Earth. 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.