IN SIMPLE TURNS HOW DO SCIENTIST KNOW HOW FAR a STAR IS FROM THE EARTH????????

Question

REFER TO ABOVE, AND BE SIMPLE, ME NO COLLEGE////

Answer 1

Distance to nearby stars can measured by the parallax method. Basically you look at the same star on two dates 6 months apart so you are seeing it from opposite sides of the Earth's orbit. You measure the angle to the star at each observation and use that information to draw a triangle with one side equal to the diameter of Earth's orbit, which we already know, and two known angles. High school math can then be used to calculate the length of the other two sides of the triangle.

For more distant stars the angles are too small to measure so they rely on a number of less direct methods, most of which depend on somehow figuring out how much total light the star is emitting and comparing that to its apparent brightness as seen by us.

Answer 2

Lasers would have no effect.... Shooting a laser at the moon works because the men who've walked there placed mirrors thar reflect the light.

Parallax, as mentioned above, works great on nearby stars. Watching the degree with which a star seems to 'move' when Earth is on one side of it's orbit as compared to another is fairly accurate.

Red Shift is another method for measuring distance, however, that usually only applies to galaxies. The light from a galaxy moving away is shifted toward the red, whereas the light from a galaxy moving towards us is shifted toward the blue. Generally, the farther away an object is, the faster it's moving AWAY from us, and consequently, the more it's light is shifted toward the red of the spectrum.

Answer 3

The most simple way to explain stellar parallax, is that if you know the length of one side of a triangle and two angles using math you can find out the length traveled before the two lines meet. You get the angles by taking measurements from earths orbit since the orbit is fixed and known you have one side, the two measurements taken at intervals during the orbit give you two angles. Once you have the triangle you use a simple formula

p"= (1AU^d) x 180 x (3600^pi {3.14159}) in arc seconds

if the parallax is 1", then the distance is

d = (1AU) x 180 x (3600^3.14159) = 206,265 AU = 3.2616 lyr = 1 arc seconds, when the distance is given in parsecs.

Answer 4

Parallax is used for stars closer than about 150 light years distance, as stated previously.

Stars further from us are more difficult. Astronomers determine the spectral type of the star, and from that they estimate how bright it really is (it's absolute magnitude). From it's absolute magnitude and it's apparent magnitude it's distance can be determined....unless there is dust and gas in between us and the star (the gas or dust will make the star look dimmer, and therefore, more distant).

Another method is by use of proper motion. Proper motion is the actual motion of a star, taking into account various abberations of light. If a star is KNOWN to be moving at some velocity toward or away from us (by use of spectral methods) then the amount IN OUR SKY it moves over a certain amount of time can be used to determine distance.

Some stars, called cepheid variables, have an absolute magnitude that can be determined by the amount of time between its variation in brightness. Once the brightness is determined it's distance can be found as well (unless, again, there is a lot of gas or dust between us and the star).

Answer 5

Where simple geometry/parallax shift fails, 2 more methods pick up--standard candles and redshift.

Certain types of stars are known to have a certain absolute brightness. If you compare how bright a star looks from earth with how bright you know it is, you can come up with distance. These stars are called standard candles.

Another method is to measure the redshift. We have observed that the universe is expanding. Everything is moving apart from most everything else. Stuff that is further away from us moves away faster. Light from a source that is moving away from us looks redder than it ought to. This is called a doppler shift. We can measure the doppler shift, calculate how rapidly the object is moving away from us, and infer how far away it is.

Answer 6

There are a number of different techniques used, but one of them is simple geometry.

The process called parallax used the geometry of triangles to determine the distance -- the diameter of the earth's orbit is the base of the triangle, and astronmers very precisely measure the angles at the two ends to the target object.

If you remember your geometry, you can draw any triangle if you have angle-side-angle, and they can do this arithmetically, and get a good value of the distance.

The farther the object is, the harder it is to measure the angles precisely, so parallax is only good out just so far, and then they have to use other methods.

Answer 7

Its basically because of global-warming.... and since the earth's temperature is rising of course the ice would melt as well.... lets take a example places like tuvalu, its obvious to see cause that place is going to sink some how because of the amount of sea water rising (due to the ice melting in the poles)

Answer 8

I'm pretty sure they use lasers. They shoot lasers toward the star, and time it. When the laser gets back, they divide the time in two, then find the distance using the speed of light.

Answer 9

using a astrolobe

Answer 10

They use lasers from Probes that are in space then all that info is then calculated and then it gets sent to the Labs. and thats how they know.