when scientists say a star is 6000 light years away, how do they measure it? i mean, wouldn't it take a laser beam 12000 years to make the round trip so they could measure it?
2007-02-01 06:58:04 · 8 answers · asked by jeffrey m 4 in Science & Mathematics ➔ Astronomy & Space
I can't believe the stupidity of some of the answers that people post on here. I wish that people would not answer if they are not sure they know what they are talking about.
The measurement of the distances to stars began with parallax triangulation. A precise measurement can be taken of the apparent position of a star against the background of stars on a given night, and then the same measurement taken again six months later, when the earth is at the opposite side of its orbit around the sun. This gives a right triangle 93,000,000 miles high.
The angle opposite the right side is obtained by measuring the apparent angular movement of the target star against the background of more distant stars. From this the length of the base of the triangle can be estimated.
After a catalog of star distances has been developed, it becomes possible to determine what characteristics of the visual and/or radio emission spectrum of a given star are indicators of its distance. This enables the star catalog to be greatly enhanced.
At some point investigators will notice the phenomenon called "red shift," which simplifies the distance estimating process even further.
All of these facts are among the most basic in the study of astronomical knowledge. Try an internet search on "astronomy."
2007-02-01 16:22:07 · answer #1 · answered by aviophage 7 · 0⤊ 2⤋
The measurement of stars distances which are not too far away is measured on the same princciple that our eyesee and measure distances. by knowing distance between two point on earth and measureing the angles ,by triangulation the distance can be calculated. There is a limit to this method because we cannot see that far when the angle becomes too smalll. This method is called the method of paralax measurements.
It would be diffucult to send a lazer beam because at lot of pwer in the beam is required. so this type of measurement is not usefull.
Another method would be to use the doppler effect. and another would be to Use intensity measurement of the radiation that the star emmits.
2007-02-01 07:24:27 · answer #2 · answered by goring 6 · 1⤊ 1⤋
A combination of methods can be used.
One method to measure the distances to far-away stars one can look at the "Red Shift" in the light emitted by the stars.
The faster a star is moving away from you, the more the frequency of the light it emits gets shifted toward the red end of the spectrum. By knowing how much the light has been red-shifted, we can figure out a good estimate of just how fast the star is moving away from us. Additionally, the farther away from us a star is, the faster it is receding. So knowing the red-shift will also give us an idea of how far away the star is.
http://hyperphysics.phy-astr.gsu.edu/hbase/astro/redshf.html
http://starchild.gsfc.nasa.gov/docs/StarChild/questions/redshift.html
http://www.wncc.net/courses/aveh/lecture/lecmeas.htm
2007-02-01 07:16:11 · answer #3 · answered by mrjeffy321 7 · 0⤊ 1⤋
They use Trig to solve the problem.
They know the diameter of the Earth (base of the triangle).
They can measure the angle to the Star from the extreme
horizon (Angle One) and later measure the angle to the Star from
the other extreme horizon after the Earth has turned around some (Angle Two).
With a triangle's base, and the two angles of the legs, you can solve for the Altitude of the triangle and get distance.
2007-02-01 07:37:28 · answer #4 · answered by zahbudar 6 · 0⤊ 1⤋
With the moon i beleive they used a effectual laser and timed how long it took to replicate back (using some type of replicate Is hould anticipate) as for planets, sorry mate don't have a clue.
2016-12-16 18:46:00 · answer #5 · answered by andie 4 · 0⤊ 0⤋
when someone says "light years" they mean the amount of time it takes to get some where traveling at the speed of light. so essentially it would take you 6000 years to get to that start traveling at the speed of light which i believe is 299,792,458 m/s. so... that means light travels 17987547480 m/minute, 107,925,848,800 m/hr, 25,902,068,371,200 m/day, 9,454,255,488,000 m/year, 56,725,529,732,928,000,000 m/6000 years. thats how far away the star is. better start walking...
2007-02-01 07:25:11 · answer #6 · answered by orange blossom honey 4 · 0⤊ 2⤋
Hi. They use parallax for the closer stars, brightness and color (temperature) for stars farther away.
2007-02-01 07:16:14 · answer #7 · answered by Cirric 7 · 0⤊ 0⤋
They're just estimates not etched in adamantium.
2007-02-01 07:16:11 · answer #8 · answered by mazaker2000 3 · 0⤊ 2⤋