Which object emits more infrared radiation: the Sun or Jupiter? Why ?

Question

I know that Jupiter radiates about 1.6 times as much infrared energy as it receives from the Sun but does the Sun emit more infrared radiation than Jupiter? Why or why not? Is it a trick question?

Answer 1

It's sort of a trick question when you include that statement comparing Jupiter's emitted vs. received IR energy. Yes, Jupiter receives less IR energy from the sun than it emits, but after all, Jupiter is about 7.79E11 m away from the sun and has a radius of ~7.15E7 m, so it intercepts only about 8.4E-9 of sun's total emitted IR energy. (The ratio is calculated as that of the disk surface area of Jupiter to the surface area of a sphere of radius = Jupiter's distance.) So the sun actually emits ~1.2E8/1.6 = 7.5E7 times the IR power of Jupiter.

Answer 2

Everything that is warm emits infrared radiation. A star like the Sun emits most of its radiant energy as visible (yellow) light. Redder and cooler stars at half the Sun’s temperature have a peak emission at near-infrared wavelengths. Infrared radiation emanating from the outer planets and their moons reveals much about their temperatures and compositions. Jupiter emits more infrared radiation than expected from absorption of sunlight, indicating that it has an internal source of heat energy. Since Jupiter is cooler than the sun, it emits more energy from the sun. Therefore, Jupiter.

Answer 3

I would guess the Sun because of one simple reason, its a lot bigger. If its bigger it emits more energy, thus more infrared radiation.