Starship Asterisk*

Beyond wrote: But how does it emit more light than it receives??

In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible or not.

geckzilla wrote:It's probably not a mistake. I've heard that claim several times and read about it out of curiosity.

Keep this in mind:

In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible or not.

http://en.wikipedia.org/wiki/Light

smitty wrote:
Just as a general comment to the APOD powers that be, if you make a statement which is virtually certain to raise eyebrows (e.g., "Neptune . . . emits more light than it receives from the sun") it would be considerate to provide a link to some generally accepted explanation.

http://en.wikipedia.org/wiki/Neptune#Internal_heating wrote:
<<Uranus only radiates 1.1 times as much energy as it receives from the Sun; while Neptune radiates about 2.61 times as much energy as it receives from the Sun. Neptune is the farthest planet from the Sun, yet its internal energy is sufficient to drive the fastest planetary winds seen in the Solar System. Several possible explanations have been suggested, including radiogenic heating from the planet's core, conversion of methane under high pressure into hydrogen, diamond and longer hydrocarbons (the hydrogen and diamond would then rise and sink, respectively, releasing gravitational potential energy), and convection in the lower atmosphere that causes gravity waves to break above the tropopause.>>

Ann wrote:But most people who visit APOD are probably not physicists, and to them, the term light probably means just visible light. When I googled "Light", I was taken to a wikipedia page about visible light. I think it would have been better to use the term energy instead of light to make people understand that the parts of Neptune that the Sun isn't shining on don't give off their own visible light.

smitty wrote:Thank you, neufer; that's helpful! My original point was simply that this link (or one like it) should have been included in the APOD which sparked all this dialogue. But better late than never. And yes, I know, we can all go out and do our own research to answer such questions, but, again, some spoon feeding of such info would be much appreciated. In general, APOD is good about doing this leg work for us. Thanks again.

Chris Peterson wrote:

Ann wrote:But most people who visit APOD are probably not physicists, and to them, the term light probably means just visible light. When I googled "Light", I was taken to a wikipedia page about visible light. I think it would have been better to use the term energy instead of light to make people understand that the parts of Neptune that the Sun isn't shining on don't give off their own visible light.

That is a reasonable suggestion, but the original statement is still accurate. Representing it as a "mistake" is incorrect.

Shamanomaha wrote:Am I right in believing that Neptune rotates the opposite direction than Earth and all the other planets?

Chris Peterson wrote:

Shamanomaha wrote:
Am I right in believing that Neptune rotates the opposite direction than Earth and all the other planets?

No, the axial rotation of Neptune is prograde (obliquity = 28°). The only planets with retrograde rotation are Venus (177°) and Uranus (98°).

http://en.wikipedia.org/wiki/Triton_%28moon%29#Orbit_and_rotation wrote:
<<Triton is unique among all large moons in the Solar System for its retrograde orbit around its planet (i.e., it orbits in a direction opposite to the planet's rotation). Most of the outer irregular moons of Jupiter and Saturn also have retrograde orbits, as do some of Uranus's outer moons. However, these moons are all much more distant from their primaries, and are quite small in comparison; the largest of them (Phoebe) has only 8% of the diameter (and 0.03% of the mass) of Triton.

Triton is in synchronous rotation with Neptune; it keeps one face oriented toward the planet at all times. Its equator is almost exactly aligned with its orbital plane. At the present time, Triton's rotational axis is about 40° from Neptune's orbital plane, and hence at some point during Neptune's year each pole points fairly close to the Sun, almost like the poles of Uranus. As Neptune orbits the Sun, Triton's polar regions take turns facing the Sun, resulting in seasonal changes as one pole, then the other, moves into the sunlight. Such changes have recently been observed.>>

ta152h0 wrote:two more years and PLUTO !!! Turn the headlights on !!!! seeing this is Sunday and the teacher is taking a break and is out of the room, I am going off-topic. How fast is New Horizons speeding past Pluto relative to Pluto ?

curious_casual_user wrote:This was also the APotD on June 18, 2006. (The full-size images and texts are identical.) Are repeats just uncommon or is this one perhaps a mistake? Not that I'm complaining! I had this as my computer wallpaper for years and don't mind seeing it again.