Astro is an apparatus, a procedure, and a state of the mind, that, when you take a big stone and repeatedly and with force smashes into your forehead ... eeh, no, ... eeh, forget it! (The physicians will complain)
How to observe the colors of the stars
editPiece of cake! Just go out and observe the stars without adapting your eyes to darkness. Dark adapted eyes have pushed on the night vision system, and that vision system is color blind. So: go out directly from the brightness inside, to the outside, take a big binocular, if you have one, and observe bright star without adaptions. You will see the colors easily, but the more you try to see, the more darkadapted your eyes become, so the colors will disappear, or rather be overwhelmed by the night vision black-and-white. The more you google, the less color you will see - in order to see colors, shut off the night vision and take a hasty glance. The first impression is the color.
It also might work to blind ones left or right (not both!) eyes by lighting a strong pocket light into the one eye you don't want to use to see the colors, I just tested, although I'm a little unsure how well it works.
One tripfall is having an open door behind you, where light streams out, I managed to see many many green stars by such a trick, by letting out yellow-red light from behind. If it's pitch black where you observe, then there will be no color distortions. Just see that you keep your night vision off by regularly blinding it.
The colors of the stars
editDespite what any color computation say, I've seen the following colors: white (Deneb), blue white (Vega), bluish white (Rigel), yellowish white (Capella), orange (Aldebaran), pink (Betelgeuse) and everything inbetween. Other colors reported, that I haven't seen: red (f.ex. TV Piscium/Y Canum Venaticorum), sky blue, greenish white (β Librae). Other colors that color computations indicate may exist: purple (WC:s), bright green (some early O:s). All greenness seems to be connected with surrounding nebulosity. What color is then that star? It depends if you would observe the star from it's own surface, or from just outside, or from Earth. Seen from Earth or from just outside, green stars seem to exist.
Planet
editI have my own definition:
- a planet is a celestial body as large (by mass) as Mercury, or upwards, but not as heavy as to produce energy by nuclear fusion, like brown dwarfs and stars.
A very very easy definition.
- Anything lighter than Mercury but as heavy as Vesta or heavier, is a sub-planet.
What those IAU speaks about when speaking about "dwarf planets" are irregular orbit subplanets and irregular orbit planets. There's nothing "dwarf" with sub-planets, a "subplanet" is by language rules too small to be a planet, while a "dwarf" is a small specimen of something, so that a "dwarfplanet" is a small planet. There's nothing "dwarf" with irregular orbits, and there's nothing "sub" with irregular orbits either. "Dwarf" and "sub" is about size.