|Posted: 2012-November-07 at 1:00am | IP Logged
True. The "red too red to see" would be infrared, or heat, which was first discovered with a thermometer. A scientist, using a prism to show the Solar spectrum, put his thermometer in the dark area beyond red, and found that there was a lot of energy there. Just like an incandescent light bulb, red stars are most energetic in the infrared.
This has two effects on potentially habitable planets around such stars. First, the habitable zone has to be calculated from the bolometric (literally, "heat"), or total, luminosity, or the planet will be placed too close and will overheat. That means that the visible light will look considerably dimmer than for a Sun-like star, where most of the energy is in visible light.
It also means that, just like the light bulb, the red dwarf will look white to an observer, as long as there is no "true white" light to compare it to. In fact, the average American 100 watt bulb is about the same temperature, and color, as an M6 star. One source says any star over about M8 would look white to a nearby observer. The bright red "red dwarfs" often seen in art wouldn't look that way at all from a nearby planet.