How can scientists know how far away a star or galaxy is?

Question

How can they measure and know that some star is like, 12,000 trillion miles away?

Answer 1

They usually know this stuff by means of bouncing lights off objects. How ever long it take for a light to bounce back to earth they can determine exagerated distance.

Answer 2

All the answers which are mentioned above have their root in the phenomena called "Doppler Effect", The Red shift which someone mentioned before is due to doppler effect.

The further the galaxy is away the less frequency it will have. Thus it will be towards the Red side of the spectrum.

The lesser the frequency the further away it is from the measuring point

Opposite is called the blue shift......

by the way Red and blue are the extremeties of the spectrum

Answer 3

Red shift only tells you how fast a distant galaxy is moving away from us. In order to relate that to distance, you need to know the Hubble Constant, which tells you how fast the universe is expanding. Hubble discovered that distant galaxies are *all* moving away from us, at a speed proportional to their distance. But you need to already know the distance to some galaxies before you can use this to tell the distance to the rest. So let's back up and start closer to the beginning.

We can measure the distance to relatively nearby stars by using parallax - measuring how much they appear to shift back and forth relative to more distant stars as the Earth moves around the Sun. With certain variable stars, we can tell how bright they are from how fast and how much they vary. An object like this whose brightness is known is referred to as a "standard candle". If you know how bright something really is, you can calculate how far away it is based on how bright it *appears* to be. The standard candles known as Cepheid variables were what first enabled astronomers to estimate the distance to other galaxies. Some of these galaxies have had type Ia supernovae in them. These exploding stars are another form of standard candle, and a very bright one that can be seen across enormous distances. Measuring the red shift of distant supernovae provided astronomers with the information needed to calculate that Hubble Constant, which lets them estimate the distance to any far-away galaxy by its red shift.

Answer 4

One way that I heard of is triangulation, basically the same way your eyes judge distances. They look at the star while they are on one side of the earth, then after the earth rotates 180(or is on the other side of its orbit) they look at it from that side and judge the distance from that. However, like our own eyes, it is only a judgement, and as far as I know, there aren't any solid ways to measure EXACT distances.

Answer 5

I believe it's a measurement called red shift. "A cause of redshift is the expansion of the universe, which explains the observation that the redshifts of distant galaxies, quasars, and intergalactic gas clouds increase in proportion to their distance from the earth."

Answer 6

calculating it's light years. that is how much time is taken for a ray of light to reach the star or galaxy is.example sun light takes about 8.3 light minutes to reach the earth.a light is 300000 * 365 * 24 * 60 * 60 = 9460800000000 km

Answer 7

interior a similar way that surveyors degree distances of uncharted land, by using arising 3 factors of a triangle, astronomers degree the distances of the celebrities. Mathematically, using trigonometry, in case you already know the dimensions of the baseline of a triangle and the arc of two of its angles, you'll be certain the gap to the third area of the triangle, and as a consequence the arc of the third perspective. by way of fact stars are so some distance away, the triangles mandatory to compute their distance could be super. Astronomers use the common diameter of Earth’s orbit around the sunlight, ninety 3 million miles x 2, or 186 million miles, by way of fact the baseline of their celestial triangle. They pinpoint a action picture star interior the sky one night, and then returned precisely 6 months later, while Earth is on the different factor of its annual orbit around the sunlight. this supplies them the concepts mandatory to be certain the action picture star’s distance and parallax, or degree of perspective between the two facets of the triangle stemming from the baseline. as quickly as the parallax is desperate, astronomers decrease it in 0.5. This equals the parallax perspective using the radius, no longer the diameter, of Earth’s orbit by way of fact the baseline of their triangle. To degree the gap to a action picture star, astronomers create an imaginary triangle between Earth, the action picture star, and Earth returned, while it has performed one-0.5 of its orbit. understanding the two base angles, they calculate the third, or parallax perspective. From the perspective measurements, they compute the gap to the action picture star.

Answer 8

my boyfriend says its measured in light years. but how many light years to the end of the galaxy or outerspace?

Answer 9

There are too many methods to measure celestial distances to list here.

Try these websites ==>http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/981102a.html
==>http://hyperphysics.phy-astr.gsu.edu/hbase/astro/distance.html