Do stars shine all the time or only at night ?
824822
They only shine at night. During the day the space gnomes turn them off to save energy.
17005
Stars seem to "twinkle " because of heat waves in the atmosphere .  They twinkle less in cold weather than in warm .
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
885615
"Shine" is an adjective. Shine must be viewed.\n\nWhile, logically, one would say the sun is shining at night, though at the other end of the world, for half of the world, it is not shining at all.\n\nThe answer is yes and no.\n\n- 16 yo Pagan
471007
Because stars are not very bright. In the day time, scattered sunlight makes the sky a bright blue, brighter than the stars. Even bright streetlights are enough to overwhelm the dim starlight.
1094079
It is most likely a satellite. Several can usually be seen every evening, if you look for them. Satellites shine by reflecting sunlight, so early evening or early morning are the best times to see them, since the sun is not in the sky for you on the ground but is in the sky for the satellite at it's high altitude.
931172
Because we are really close to our star, the sun.  The light from it drowns out the other lights from stars.  The same way a very small light in a room is drowned out by turning on a much larger one.  At night, we are completely turned away from it, so we can now see other lower light sources.
999350
Well, in a very general sense, it's best to view stars and *some* planets between 10pm and midnight.  You'd have to look up the positions of each planet (or the major ones, anyway) to figure out when all of them are in sight.
814528
The best time= at night
752575
The 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). \n\n\n---------------------------------------------------------------------------------\nStars, except for the Sun, although they may be millions of miles in diameter, are very far away.  They appear as point sources even when viewed by telescopes.  The planets in our solar system, much smaller than stars, are closer and can be resolved as disks with a little bit of magnification (field binoculars, for example).\n\nSince the Earth's atmosphere is turbulent, all images viewed up through it tend to "swim."  The result of this is that sometimes a single point in object space gets mapped to two or more points in image space, and also sometimes a single point in object space does not get mapped into any point in image space.  When a star's single point in object space fails to map to at least one point in image space, the star seems to disappear temporarily.  This does not mean the star's light is lost for that moment.  It just means that it didn't get to your eye, it went somewhere else.\n\nSince planets represent several points in object space, it is highly likely that one or more points in the planet's object space get mapped to a points in image space, and the planet's image never winks out.  Each individual ray is twinkling away as badly as any star, but when all of those individual rays are viewed together, the next effect is averaged out to something considerably steadier.\n\nThe result is that stars tend to twinkle, and planets do not.  Other extended objects in space, even very far ones like nebulae, do not twinkle if they are sufficiently large that they have non-zero apparent diameter when viewed from the Earth.\n-------------------------------------------------------------\n\n\nI can be more specific, sure. Remember that just like a computer screen, your eye is composed of a certain number of "pixels," each represented by a single light-receptor cell in your retina. If two (or more) points of light are close enough such that they are focused on the same receptor cell in your eye, you will experience them as a single point of light. This is referred to as the "resolution" of your eye, or any telescope for that matter. \n\n\nNow, a star on the sky is in a true sense a single point of light. All the light comes through the atmosphere in exactly the same direction, through exactly the same atmospheric turbulence, and thus is bent in exactly the same way. So when it gets to your eye, the amount of light you see coherently varies. It also strikes (primarily) only a single receptor in your eye. \n\n\nOn the other hand, light from a planet is different. Each of a few receptors in your eye sees a large number of light rays coming f
231023
This is caused by thermic convection of the air. In the deserts you normally have high differences in temperature between day and night, so hot air is rising rapidly while cold air is moving downwards after sunset. This different densities in the air makes the light bend and the stars seems as if they are dancing, just as if you were looking through an irregular glass. \nIt's a bad night for astronomers.
28842
it depends on your place in space. are you in a straight line with a planet and sun,  then there is night and vice versa
970874
In your context brightness and luminosity do mean the same thing, and that is the total amount of light given off by the star.\n\nHowever brightness can sometimes mean surface brightness, which is luminosity per unit area of the star. So a red giant has a low surface brightness, but the large surface area of the star gives a large total luminosity for the star as a whole.
650511
None, they up in the Sky, best seen at night. The Earth does revolve around a Big Star that can actually be seen in the day and not night. Make for a good Word Play/Riddle question. ;-D
37735
Stars are like our Sun. Not comets at all. Comets are dirty, big snowballs that have no light at all. The twinkling comes from heat radiating from earth which makes the light spectrum shift in different colours. Symbols that represent something doesn't often look like the original. Take the symbol for a heart for example. But it's easy! :) Try to draw a immensly huge boiling, burning piece of gas that throws tons of particles out from it in lightning speed and see if anyone understands what you drew. Now try to make it into a character that you can type on a keyboard :)
166889
I live in a small town in the midwest and make it a point to go out and do some stargazing.  The street lights do wash out some of the dimmer stars, but there are still a lot of stars to see.  Going out into the countryside will reveal a lot more stars.  Not only the stars though, in the last week I have also seen Mars, Venus, Saturn, Jupiter and Mercury..and the most fantastic cresent moon in the early morning.  If a person can get up into the mountains at night (no mountains where I am at), the sky is very full of stars...way too cool.
178092
Not necessarily.  A star is only a sun if it has planets around them.  But all stars look like suns.