continuous spectra
The Sun -- a typical star
- T = 6000 K
- Peak wavelength 500 nm, green, spot in the middle of the visible wavelengths
- eye was developed through evolution to respond to the light which was present
- other stars also visible to the eye
- planets aren’t, except by reflected sunlight
- Total emission from sun 4 x 1026 W
- huge power
- source of energy nuclear fusion in core of sun
- at earth, solar power ~ 1 kW/m2 (show on board -- inverse sq law)
- basic source of energy for life on earth
- industrialized humans use about 1 kW of electrical power on average