why do stars twinkle whereas planets dont????
139013
The main reason that heavenly bodies appear to twinkle is because of materials between them and your eyes - normally it's atmospheric interference which makes them appear to distort and shift. This actually happens with planets as well, but it's less obvious because they appear larger in the sky and so minor distortions don't have such an effect.
625420
A star is any massive gaseous body in outer space, just like the Sun. Unlike a planet, a star generates energy through nuclear fusion and therefore emits light. All stars except the Sun appear as shining points in the nighttime sky that twinkle because of the effect of the Earth's atmosphere and their distance from us. The Sun is also a star, but it is close enough to Earth to appear as a disk instead, and to provide daylight.
356177
In lay man's terms:\n\nA star: a huge ball of fire, emitting heat and light, mostly composed of gasses and the source of the heat is the nuclear reactions happening isnide it due to the massive pressure in its core. An example is the sun, the temperture of its surface if more than 5000 degress centigrade, while the temperature of its core is several million degrees. A star is 'usualy' much larger than planets(thouthands to millions of times larger) . Some stars have planets orbiting around them (e,g, our sun)\n\nPlanets: Intert masses that do not emit light or radiate heat. Planets revolve around stars and are far much smaller than stars(e.g. earth, mars, saturn, jupiter,etc). Some planets have moons(much smaller planets) revolving around them.Mostly planets are solid masses, but sometimes they are made of gases. The temperature of planets is far cooler than stars.
1173785
Stars don't move our sun is a big star it is our planet that orbits our star so that is why it seems like the stars move my lov.
168006
If it doesn't move or twinkle, it is the planet Venus.\n\nThis answer brings me to level 3.  Thanks all!
141087
mainly :\nstars generate light, planets only reflect\nplanets move through an orbit (around stars), stars don't
643905
WHY DO STARS TWINKLE?\n\n\nTwinkle, twinkle, little star,\nHow I wonder ...\nThe scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation). Stars twinkle when we see them from the Earth's surface because we are viewing them through thick layers of turbulent (moving) air in the Earth's atmosphere. \n\nStars (except for the Sun) appear as tiny dots in the sky; as their light travels through the many layers of the Earth's atmosphere, the light of the star is bent (refracted) many times and in random directions (light is bent when it hits a change in density - like a pocket of cold air or hot air). This random refraction results in the star winking out (it looks as though the star moves a bit, and our eye interprets this as twinkling). \n\nStars closer to the horizon appear to twinkle more than stars that are overhead - this is because the light of stars near the horizon has to travel through more air than the light of stars overhead and so is subject to more refraction. Also, planets do not usually twinkle, because they are so close to us; they appear big enough that the twinkling is not noticeable (except when the air is extremely turbulent). \n\nStars would not appear to twinkle if we viewed them from outer space (or from a planet/moon that didn't have an atmosphere).
226086
Even though it is considered a planet Jupiter is almost a star.It doesen't put out light but it does put out heat.If it had been a little bigger it would have become a star.
933426
At the zenith, you can observer an astronomical object through the least amount of Earths atmosphere.\n\nThe more atmosphere that the light from the object passes through before hitting your eyes (or telescope), the more blurry the image. This is what causes stars (and planets to a lesser degree) to "twinkle".  It follows that since you are looking through less air, starlight  is also less affected by dust particles and air currents.\n\nStill, cold, thin air = good seeing. (One reason why most of the major ground based observatories are at high altitudes)
1010582
it is the difference in brightness between the stars and any astronaut, cosmonaut, space shuttle, or international space station.  the stars are just too dim.  a much longer exposure time is needed to photograph dimmer objects.  ask someone who knows about photography.\n\nhttp://en.wikipedia.org/wiki/Photography
12842
Our Sun is a star and is thus made of the same materials (in general) that the rest of the stars are.\n\nBut because of different ages and environments, there are probably no two stars that are exactly alike.
725115
These galactic clouds only glow if there are hot stars to stimulate them. The gas in the cloud  glows in a way similar to the gas inside a fluorescent lamp, but it's ultraviolet light, not an electric current, providing the stimulation.  Typically, it is very hot O and B stars formed within the cloud that provide the stimulation.\n\nPortions of the gas cloud away from these bright stars are dark. You can see this in M42, the great Orion nebula. The dark areas in that nebula are actually parts of the cloud obscuring brighter parts of the same cloud behind them.
51021
No. Planets orbit stars.  The earth is a planet orbitting its star, the Sun.
883747
And because giant planets such as Saturn and Jupiter are mainly gaseous they are probably failed stars. Pretty cool?! Astronomers are watching a surprising storm suddenly appearing in Saturn and wondering what is going on there. Astronomy is a fascinating hobby or profession since there is still so much to learn even about the objects closest to Earth.\n\nJLH
75743
Twertyto's answer is the best! When I was just learning about astronomy I asked the same question. Someone told me a very simple answer that just might work for you:  A planet reflects light and a star creates it. That sounds simple enough for simpler times! But now welcome to the 21st century!!!\nBrown dwarfs are kind of the "animal" that bridges these two seemingly different objects. Astronomy is having a hard (but fun) time right now trying to decide exactly what a planet is- from the very large to the very small. Is an object 75 times the size of Jupiter a planet? 79 times? 81 times? No one seems to know. Do we call them planets or officially name them Brown Dwarfs. On the other side of the issue, is Pluto a planet? They just discovered a larger than Pluto object and several almost-the-size-of-Pluto objects out past Pluto's orbit. Are all of these planets? If Pluto's not a planet, but now has been discovered to have at least 3 moons (two new one's were just discovered recently), then what do we call it? \nThis has been a surprisingly tough answer for Astronomers as well, so not only is it a great question, but you- and everyone else- might have to stick around for a while for the difinitive answer!!!
825270
Planets and stars can both twinkle, its called astronomical scintillation.  In short it is caused by fluctuation in air density and temperature.  Since stars and light both send light to earth (planets reflect a stars light whereas the star produces it's own) the twinkling effect can be seen in either.  And thus if you were standing on another planet, it IS possible that earth would appear to twinkle.  It's not guarenteed, but if the light coming from earth passed through some varying densities and temperatures it could appear to twinkle.  Refer to this article for more on "twinkling":\n\nhttp://en.wikipedia.org/wiki/Scintillation_%28astronomy%29
683582
There are about a couple hundred billion stars in our galaxy. The stars close to the center are not likely to have planets because of dynamical considerations (other stars pass by too frequently to have stable orbits).\n\nThe BIG question is how many planets there are per star on average. Our sun has ten planets and assorted other objects. We have found many other planets orbiting other stars, but most of those stars have only one planet (that we have detected). One has three planets that we know about. HOWEVER, the way we detect these planets favors detecting large planets that are very close to their star. Once you start to ask about planets as small as Saturn, or that are farther away than Mercury is from our sun, the methods don't work so well.\n\nThe upshot is that we really just don't know how many planets a typical star has. Some probably have none. How many have none? We don't know. How many have ten smallish planets? We don't know. At best we can guess, say 4-5 on average. This would give close to a trillion planets in our galaxy. The number could easily be a tenth of this, though.