quite a bit of information on the sun you won't hear elsewhere
Skylab, the first space station, was launched in 1973 specifically to study the sun without atmospheric interference.
Galileo was the first, in the 1600s, to turn a telescope on the sun. He discovered that the sun was not perfect: it had dark spots. And that these rotated. The sun spins on its axis.
About 3 times per decade there is a total eclipse of the sun somewhere on Earth. At these times the corona can be seen from Earth.
Father Angelo Secchi https://en.wikipedia.org/wiki/Angelo_Secchi in the mid-1800s was the first to use spectroscopy to study the sun. By using only the light from a narrow portion of the spectrum he could see detail that otherwise is swamped in the brightness. Spectroscopy also identified that the sun is mostly hydrogen and an element unknown on earth, that was named helium (Helios, god of the sun). There are other elements present in the sun as well. Secchi then used his spectroscope on stars. Same elements. The sun is a star. Secchi discovered this in 1862.
Rockets by the late 1940s got above the atmosphere: instruments detect cosmic rays, x-rays, and ultraviolet light, all from the sun, that our atmosphere shields us from.
The first person to do a spacewalk, outside a space capsule, was Alexi Leonoff.
Skylab captured 160,000 pictures of the sun in 9 months. Images included coronal mass ejections.
Astronomer Hale in 1903 built the Mount Wilson observatory near Pasadena, California. The road to the top wasn't built until 1936. The steel and concrete was packed to the summit using horses. At this observatory, spectrographs show high resolution images of sunspots. In the sunspots, spectral lines widen and split. This is evidence that sunspots are areas of intense magnetic field. In the dark spots, the magnetic field suppresses the emission of plasma, lowering the surface temperature 2000 degrees. There are other areas where the emission is more intense.
The northern and southern lights, the aurora, are due to the interaction of ions from the solar wind with Earth's magnetic field. This was discovered by a Norwegian astronomer before World War I.
Chinese astronomers had noticed comet tails always point away from the sun. Light alone could not do this. The solar wind is 300 km/second to 800 km/second, at all times. This was measured by Mariner 2 on a flight to Venus in 1962, having been predicted 5 years earlier.
The solar wind streams from the sun's equator, which is the plane the planets orbit in. Mercury's atmosphere has been completely stripped by this wind. Venus's atmosphere, 100 times as dense as Earth's, is being blown toward Earth's orbit by the solar wind. Mars has 1/100 the density of Earth's atmosphere.
Solar wind interaction with Jupiter's magnetic field emits radio waves. Same with Saturn, Uranus, Neptune.
Solar wind doesn't continue forever. The key is that interstellar space has hydrogen and helium in it. The solar wind is pushing this interstellar gas away from the sun. There is a point at which the solar wind has lost its force to the point where the interstellar gas pushes back at the same force as the solar wind. This is called the heliopause. It's at about 4 times the radius of Pluto's orbit. When a coronal mass ejection reaches the heliopause, it emits a burst of radio waves. These radio waves are detected 400 days after the coronal mass ejection.
In 1995, the SoHo observatory was launched. It looks at the sun in the x-ray, ultraviolet, and visible spectra, and listens for sounds emitted by the sun! Sound lets scientists discover what's happening below the surface of the sun. There are rivers of plasma beneath the surface, circling around the sun's axis. Every 6 minutes, the sun breathes in and out.
The sun was formed 4.5 billion years ago when a supernova caused a gas cloud to collapse and begin fusing hydrogen into helium.
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