Can someone explain the speed of light and how we know things are that far away?

Question

Ok so I am just wonderingg here, how did we come up with the speed of light? Furthermore how do we know things are x number of light years away? I get the general concept but how was it proven and how do we estimate the light year distances?

Answer 1

The first reasonably accurate measurement of the speed of light was done by an astronomer named Fizeau, who noted that the revolution of the moons of Jupiter was occurring at something different than the expected times; he correctly deduced that the effect was due to the finite speed of light and varying distance to Jupiter. Many methods have been used to measure the speed of light since then, giving much improved accuracy. In fact, the accuracy is now so good that the speed of light is used as one of the fundamental constants of physics.

The distances to stars are measured by the following means:
- Triangulation, using the opposite sides of the earth's orbit as one side of a triangle. The other sides can be measured by the parallax; a shift of a star position by one second of arc represents a distance of 3.26 light years and is called a parsec.
- Cepheid variable stars. Some stars change their brightness with a characteristic period which depends on the star's luminosity. By comparing the apparent brightness with the actual luminosity, the distance can be determined.
- Red shift. Distant stars are moving away from us, at a speed which depends on the distance. The Doppler shift resulting from that motion gives the distance.

Answer 2

The speed of light is usually measured by carefully timing how long it takes a flash of light to go to a distant mirror and return.

The distance of stars are measured by triangulation based on the apparent shift in its position as seen from opposite ends of the Earth's orbit.

A light year is just a made up way to talk about long distances. Knowing the speed of light is not necessary to measure the distance of stars.

Answer 3

We estimate distances through triangulation, and we know the speed of light by measuring it.

The speed of light can be measured by observing expected astronomical phenomea when you know the distance. For example we know a lot about the planets in our solar system and their moons, and we can measure how far they are away from us so if we measure the delay between when one of the moons movements is supposed to happen and when you actually see it, then you can measure the speed of light.

Answer 4

the speed of light was first calculated long ago by measuring light coming from a star that was occulted by jupiter. now we can measure it in a labratory.

many distances in space are found by triangulation. nothing to do with the speed of light really, its just used as a unit of measure. further distances in space are measured by other methods such as supernovae or cepheid variables.

Answer 5

There are 2 subject concerns at play right here. First is that as quickly as you talk approximately that products and lightweight shuttle in all guidelines, it could be achieveable for pictures, a minimum of, to truthfully be two times as some distance from one yet another in mild years than the age of the universe, by way of fact they have been vacationing in opposite guidelines for all that element. the 2nd concern is cosmic inflation. Cosmic inflation is a thought the pertains to the enlargement of the very early universe. the main suitable thank you to describe that's to declare that on an analogous time as no longer something can shuttle by using area at a extra physically powerful speed than the fee of sunshine, area itself can truthfully boost speedier than that under particular situations. So it is achieveable for cosmic products to be farther from us in mild years than the age of the universe, yet we heavily isn't waiting to work out them by way of fact they are so some distance faraway from us that no mild from them has reached us yet.