Solar physics
11 questions tagged Solar physics — spanning every one of the seven Ws.
Why is the Sun’s corona visible during a total solar eclipse?
The Moon blocks the Sun’s bright disk, revealing the faint outer atmosphere of the Sun, the corona.
What is the Parker Solar Probe?
The Parker Solar Probe is a NASA spacecraft designed to study the Sun up close. It has flown closer to the Sun than any previous spacecraft and samples the corona directly.
Whose spacecraft first measured the solar wind close to the Sun?
NASA’s Parker Solar Probe, named after Eugene Parker, is the first mission designed to repeatedly enter the Sun’s outer atmosphere. It has made the closest-ever approaches to the Sun since 2018.
Why is the Sun’s corona much hotter than its visible surface?
The corona reaches about 1–3 million K, far hotter than the Sun’s surface at roughly 5,800 K, because magnetic fields dump energy into the upper atmosphere.
Why does the Sun have an 11-year activity cycle?
The Sun’s magnetic field reverses roughly every 11 years, creating the familiar sunspot and flare cycle.
What is the Sun’s corona?
The Sun’s corona is its outer atmosphere, a faint halo of extremely hot plasma visible during a total solar eclipse. It can be millions of degrees Celsius.
Which spacecraft first observed the north pole of the Sun from above the ecliptic plane?
ESA and NASA’s Ulysses spacecraft was the first to study the Sun’s polar regions from a high-inclination orbit. It used Jupiter’s gravity in 1992 to tilt its path.
Which force is key to nuclear fusion in the Sun?
The weak nuclear force is key to the first steps of fusion in the Sun. It allows a proton to turn into a neutron in the proton-proton chain.
What is a synoptic map of the Sun?
A synoptic map is a full-surface map of the Sun assembled over time as the Sun rotates. It helps scientists track magnetic activity across the entire solar disk.
Where is the Sun’s north pole observed by spacecraft?
No spacecraft can stay fixed over the Sun’s north pole, but missions like Solar Orbiter observe it from tilted solar orbits. Solar Orbiter has used repeated close passes to view the poles from above and below the solar equator.
Which force allows the Sun to produce energy by fusion?
Fusion in the Sun depends on the strong nuclear force and the weak force. The strong force lets nuclei combine, and the weak force helps convert protons into neutrons in the reaction chain.