Astronomy
The Sun and space weather
Solar structure, spots, flares and CMEs.
Basics
The Sun
Core fusion of hydrogen, then radiative and convective zones, then photosphere. Sunspots are magnetically strong and relatively dark. Cycle ~11 years. Flares and CMEs send particle and electromagnetic disturbances.
Space weather
The solar wind hits Earth’s magnetosphere — aurora. Strong storms can rattle satellites, grids, and HF radio. Forecasts watch coronagraphs, fields, and particles.
Formulas
Solar constant (sketch)
About 1366 W/m² at Earth orbit, above the air. Season and atmosphere change the ground value.
Symbols
-
L_⊙solar luminosity -
aEarth–Sun distance
Key table
| Photosphere temperature | about 5800 K |
|---|
In this field
Solar system
Planets, Kepler, gravity, escape speed.
Stars
HR diagram, fusion, lifetimes, magnitude.
Galaxies and cosmology
Galaxies, Hubble, redshift, black holes.
Observing basics
Celestial sphere, coordinates, telescopes, spectra.
Exoplanets and life
Detection, habitable zone, a SETI sketch.
Moon, tides, and eclipses
Lunar phases, tides, and solar and lunar eclipses.
Magnitudes and spectra
Apparent and absolute magnitude, distance modulus, colour and spectral type, Wien’s law.
Galaxies and Hubble
Galaxy shapes, rotation curves, the Hubble–Lemaître law, and a standard-candle sketch.
Telescopes and light
Aperture, diffraction limit, collecting area, seeing versus space telescopes.
Stellar death
Red giants, supernovae, and sketches of white dwarfs, neutron stars, and black holes.