What's the difference between a light year and an Astronomical unit?
So you're asking what the difference is in miles? That's rather complex for calculators or anything. (186000 times 31536000) minus astronomical unit distance.
(5.865696 * 10^12) - AU
About 5.86 trillion miles minus the distance of an AU.
I think around 5865603000000 miles, or 5.865603 trillion. Not very big in proportion.
What is a light year, how is it equal to 6 trillion miles?
How Far is a Light-Year?
A light-year is a unit of length used by astronomers to measure interstellar distance (the distance between stars). A light-year is defined as the distance that light will travel in a year. If the speed of light is 186,000 miles per second (300,000 km per second), then calculate the distance that light will travel in one year. Express your answer in miles per year. [Note: Cancel similar units above and below the dividing line. This process is known as "dimensional analysis."]
186,000 mi/sec x 60 sec/min x 60 min/hr x 24 hr/day x 365 days/yr
Answer = 6 trillion miles
What is the period of time light travels in one Light Year?
A light year is a measurement of distance like a yard or a mile. A light year is the distance light travels in one year. in miles it is about six and a half trillion miles. And yes if a star is 100 light years away it means it took the light 100 years to get here. Any thing you observe is something that happened 100 years ago.
Indeed, a light year is the DISTANCE light travels in one year, it is not a time.
If you, for reasons unclear to me..., want to know the distance in meters that light travels in one (earth) year, multiply the velocity of light (3 * 10^8 m/s) by the number of seconds in an Earth year (I always remember that that number of seconds is appr. pi * 10^7 seconds ;-)
there are some theories that state that the universe can bend through dimensions, so that basically light can go from one side of the universe to the other in a second. in this theory, we can also say that if we are not within distance of touching something, that object could be on the side of the universe, and if we get closer to it, then we could also have gone to the other side, by way of dimensions. i dont know the names of these theories, but basically they assume that the universe it not flat(but rather bent and can move), and that the universe not only has 3 spatial dimensions + 1 dimension of time, but even more. string theory suggests 26 dimensions.
light is considered masslass, if it were to travel faster than light (like theoretical tachyons) it could rip spacetime and create a wormhole. its all theory.
How can scientists mesure the distances of a light year of Stars in the others galaxies ?
I presume your question is about determining distances to stars, and galaxies.
For relatively near stars, the parallax method is used, where the orbit of the Earth around the Sun, with observations done 6 months apart, will create a very small, but still measurable, apparent motion of nearby stars against a much more distant background.
For more distant stars, the spectral type to luminosity relationship is used. Since the stellar theory provides a relation between stellar type (the color of the star) and how bright it is in absolute term, how bright it appears as seen from here is thus a function of how far away the star is.
For galaxies, yet another couple of techniques are used. One uses the variables stars, the brightness of which is a function of the absolute luminosity; and another one uses supernova, again, theory shows how bright they should be. Of course, this requires a supernova to be observed.
Finally, there is the Doppler effect, as galaxies are usually moving away from one another in the expansion of the universe, the speed a galaxy is moving away from us correlates with how far it is; see about the Hubble constant for more details.
The Earth is 8.3 light minutes from the Sun, these 8.3 minutes is how much time it takes for the light from the Sun to reach us.
A light year is a measurement of distance...the distance of how far a beam of light will travel in one year, and is equal to 5,865,696,000,000 miles.
The speed of light (how far a beam of light travels in one second) is 186,282.4 miles per second.