which celestial body appears never to move in the night sky?
101906
Right; it's the North Star. The reason it doesn't move is that it's in the direction of the earth's rotation; that is, if you extended a line through the north and south pole, you'd get pretty close to that star. Everything else just rotates around that point.\n\nHere's a neat photo of what this looks like; the North Star is in the center of the swirls:\n\n  http://www.gdargaud.net/Climbing/Utah/StarRotation.jpg\n\n\nYou might want to put this in the Astronomy/Space category, by the way.
327029
I was observing Alpha Orinis (Betelgeuse) through my telescope, and I saw something seem to fly towards it, then head the other direction. I don't know what it is. Thus it was unidentified. It was obviously flying, and I will assume its an object. There you go. A UFO. Therefore, anything that is in the air, and you dont know what it is, is a UFO.
496226
STARS AND NEBULAE.\n\nMost of the things you can see in the night sky are stars: a few thousand are visible to the unaided eye. A star is a hot ball of mostly hydrogen gas; the Sun is an example of a typical, ordinary star. Gravity keeps the gas from evaporating into space, and pressure due to the star's high temperature and density keeps the ball from shrinking. In the core of the star, the temperature and densities are high enough to sustain nuclear fusion reactions, and the energy produced by these reactions works its way to the surface and radiates into space as heat and light. When the fuel for the fusion reactions is depleted, the structure of the star changes. The process of building up heavier elements from lighter ones by nuclear reactions, and adjusting the internal structure to balance gravity and pressure, is called stellar evolution. \nLooking at a star through a telescope can tell us many of its important properties. The color of a star tells us its temperature, and the temperature depends on some combination of the star's mass and evolutionary phase. Usually, observations also allow us to find the luminosity of the star, or the rate at which it radiates energy as heat and light. \nAll stars visible to the unaided eye are in our galaxy, the Milky Way. The Milky Way is system of roughly 100 billion stars, along with a great deal of interstellar material. The galaxy is shaped like a flattened disk embedded in a round, faint halo. Gravity keeps the stars from drifting away, and the motions of the stars keep the system from falling in on itself. The Milky Way has no distinct edge - the distribution of stars tapers off gradually with increasing distance from the center. The SDSS detects stars more than a million times fainter than can be seen with the unaided eye, far enough to see the outer structure of the Milky Way. \nStar Colors and Luminosities: The H-R Diagram\nAstronomers often make plots of the luminosities of stars compared to their colors. The first such charts were made in the early twentieth century, when astronomers took spectra of thousands of stars, then placed the spectra into a sequence based on the appearance of several different features. The classes of stars were given different letters as names; in order of decreasing temperature, they are OBAFGKMLT. The hottest stars are class O, while the coolest are class T. Two astronomers, Ejnar Hertzsprung and Henry Norris Russell, independently started to wonder what would happen if they compared stars' luminosities to their spectral classifications (or, alternatively, to their temperatures). They knew that some stars were hotter and more luminous than the sun, and that others were cooler and less luminous. Hertzsprung and Russell found that 90% of the stars fell into a narrow band they termed the "main sequence." Today, we call this type of plot a Hertzsprung-Russell (or H-R) diagram. \nAstronomers further divide each letter into ten categories from 0 to 9, with 0 being the hottest star in that spectral class and 9 being the coolest. So, a B1 star is hotter than a B2 star, and a B9 star is hotter than an A0 star. Our own sun is at the "hot" end of the G range with a surface temperature of 5,770° K; therefore, it's called a G2 star. \nSpectral classes give us a convenient way to refer to most types of stars - from O0, the hottest at over 25,000° K, down to T9, the coolest failed stars at 1,000° K. Each spectral type of star is associated with a specific color: all G-type stars like the sun are yellow, all M-type stars appear red, and all B-type stars are bluish. Thus, this system of letters and numbers tells us where a star is on the horizontal (color or temperature) axis of the H-R diagram. \nTwo alternative systems tell us approximately where on the vertical (luminosity) axis a star can be found. One system uses absolute magnitude, a measure of luminosity derived from the apparent magnitude, or brightness of the star
757196
Betelgeuse is a constituent of Orion, which should be visible in the evening at this time of year.  Use a star chart to see exactly which star of Orion it is.
346966
Greetings,\n\nIt was probably Sirius the Dog Star.  One of the closer stars to us and when it twinkles it appears red, blue, green, and is really big for a star.\n\nIt was NOT a planet, as planets don't twinkle.  Jupiter is bright, but it's not very high up in the sky at 8:00 pm.  Venus is currently only up in the morning.  Saturn is a dim yellowish star in Gemini.  Mars is a dim orange star between Taurus and the Pleides.\n\nSo to sum up, it was most likely Sirius.\n\nYou can use the link provided for a interactive star chart that is easy to read and use.  Simply plug in your city and state and the time of day/night you want to see and most of the visible stars will show up along with the planets, comets, and a few other deep space objects.\n\n-matt
279860
natural sattelite :the moon\nbiggest body and gravity :the sun, it keeps all the planets in out solar system\n\n~Brendon
438834
If you mean an official spaceship or saucer, well...no. \n\nBut if you mean "Unidentified Flying Object," then I did see a triangular shape (three dull orange lights) flying very, VERY fast across the horizon of Utah once. I learned later it might have been a stealth bomber moving from one base to another, but MAN that thing was quick. It's exact identity was never confirmed.
585811
This question may be interpreted in two ways.  First, why is the sky not blue at night?  The answer for that is that the sky appears blue during the day because it scatters high energy sunlight.  The atmosphere scatters high energy starlight as well, but there isn't enough of that to make the sky appear blue.\n\nThe other interpretation is why is the sky not totally lit by stars?  That is actually a very important question that was pondered by famous astronomers.  It is called the Dark Night Sky Paradox, or Olbers' Paradox, and was contemplated by such notables as Halley and Kepler as well as the eponymous Heinrich Wilhelm Olbers.  If the universe is of infinite age (as was once assumed) and static, and the stars have had eternity to shine, shouldn't the sky be lit?  \n\nSome people hypothesized that the stars did not appear randomly in all directions.  (So the stars are arranged in straight lines with the Earth at the center so that starlight piles into intervening stars, and there are empty gaps?  Even before Hubble proved that "dark sky" is teeming with distant galaxies, that sounded stupid.)  Others said that dust in the way absorbed starlight.  But after an eternity of absorbing starlight, wouldn't the dust glow as well, and light up the night sky?\n\nThe fact that space is dark turns out to be proof in part that the Universe is not infinite, eternal, and static.  That in fact it had a beginning point in time and space and the Universe is changing.
515493
The galaxy is everything you see at night when you look up in the sky. Stars, planets, moons, asteroids, meteors, comets, or any other terrestrial body. I think there's just one black hole at the middle of the galaxy.
46281
Saturn is a gas giant, so it has no surface.
48781
kinda, but it isn't a star. it's fragments of space debris, meteors etc, burning up whilst passing thru the earth's atmosphere. From the ground it appears like a star shooting across the sky, hence it's name.
254255
1 for every star.  Even if a star has no accompanying rock debris, it still has a "solar system" associated with it, just that it's empty.
1166968
There are many differences.\n\nBy the wording of your question, it sounds like you are speaking about the movement of celestial bodies.\n\nMost stars (except the sun, seem to stay in the same position in relation to one another.  The sun, moon and   the planets, change their position against the background of the "fixed" stars.  \n\nThis is because the objects in our solar system are close to us, so their change in position is much easier to see.  The fixed stars are so much further away, that their motion is harder to detect.\n\nThis is similar to the experience of riding in a car.  If you look at a distant mountain,  the appearance of it doesn't change very quickly.  But as you come close to a street or a building, the appearance changes dramatically. \n\nThe reason is that if you measure apparent motion by an angle,  an object twice as far from you must move twice the distance across your Field of vision to have the same apparent motion.
184318
Mercury, Venus, Mars, Jupiter, Saturn AND Uranus (many people forget this one)\n\nWith a magnitude of 5.8, Uranus is visible with an unaided eye.\n\nIt is so faint, and moves so slowly, however, that it wasn't identified as a planet until after the telescope was invented.\n\nHowever, on a very dark night and if you know exactly where to look (and have good vision), Uranus is visible with the naked eye.
39095
No. \n\nStar:\nA self-luminous celestial body consisting of a mass of gas held together by its own gravity in which the energy generated by nuclear reactions in the interior is balanced by the outflow of energy to the surface, and the inward-directed gravitational forces are balanced by the outward-directed gas and radiation pressures\n\nPlanet:\nA nonluminous celestial body larger than an asteroid or comet, illuminated by light from a star, such as the sun, around which it revolves.\n\nSo, stars are self-luminous (have their own light) and are stationary. Planets don't produce their own light and revolve around a star.
624353
gravity is everywhere - even in space.  what do you think holds everything together, keeping jupiter from sailing off towards alpha-centauri?  \n\non to your question - shooting stars are not stars, they are meteorites - varying sized "rocks" that are orbiting whatever has them stuck in a gravitational orbit until they encounter the earth's atmosphere, and burn up, which is what you see and call a "shooting star."  most never hit the ground, but when they do, look out!
506536
It's the only object outside our own galaxy visible with the naked eye. But you have to be in a very dark area, i.e. well away from any major cities.