Self luminous planets
Jupiter and Saturn are self-luminous
- expect T from balance
- sunlight absorbed = infrared emitted (~T4)
- find actual T is elevated vg of spectrum
- Radiating ~ 2 x as much as absorbing from Sun
- i.e. if sun turned off
- Earth, etc. would cool way off
- Jupiter and Saturn would remain bright in the infrared
- energy source is trapped heat from formation 4.6 b.y. ago
- during formation, grav’l energy converted to heat
- central T ~ 100,000 K at formation
- currently down to 30,000 K
- heat energy slowly leaks out
- Not a star
- H fusion requires T > 3,000,000 K
- resemble “brown dwarf”
- failed star, M < 0.1 Msun