what are the 2 ways that scientists can tell how far away from earth a star is?

Answer 1

One way is through the measurement of parallax, that is, the apparent displacement of nearby stars with respect to background stars due to the rotation movement of Earth. This is the most direct way, and it does not make any assumptions about the particularities the the stars being studied or the medium through which light travels. See, e.g., http://en.wikipedia.org/wiki/Parallax.
Another is through the relation between absolute and apparent magnitude as a function of distance. See, e.g., http://en.wikipedia.org/wiki/Absolute_magnitude.

You should notice that redshift does NOT indicate distance, only relative velocity. Stars in our galaxy are not receeding away from us, but circling the centre of the galaxy. Redshift is used to measure distance to distant galaxies, not individual stars in our galaxy. It's not even useful to some galaxies - for example, the Andromeda galaxy is moving in the direction of the Milky Way, which means its redshift is blue! Also, cepheid measurements have limited use - they can only be used to set distance to these stars, and by extension to their home galaxies.

Answer 2

You have lots of good answers already, but I would say that Parallax measurements accurately tell us how far off NEAR stars are.
You can do a classic, simple demo of parallax by holding a pen upright at arms length in front of you. Close one eye and align the pen with some fixed object further from you, say a corner of the room or a doorway. Now open your eye and close the other. You will see that the pen is no longer aligned to the background reference point. Now repeat with the pen held farther from you and observe the variations of the parallax effect.

Distant stars may be measured if you can identify what type of star you are observing, for example a star known to be a main sequence star similar to our sun will have an absolute brightness related to its distance from any point using Newton's inverse square law. (This method makes many assumptions about the interstellar or intergalactic medium seperating us from the star!)

As mentioned Cephid variable stars have theoretical brightnesses and these are good to use when measuring Galactic distances.

Also, as mentioned, redshift is related to distance using somth called the "Hubble constant", and implies that redshift and relative velocity ARE related. So, knowing the degree of r-shift of any object, gives a measure of distance.
Good luck.
MM

Answer 3

One way is parallax. This is where you look at an object from two different locations and see how that object's apparent position changes with respect to its background. (If you look at an object with one eye closed, and then with the other eye closed, you can see this effect). This is very difficult to measure because the stars are so far away and the parallax is so small, even if you use the extremes of the Earth's orbit around the Sun as the points you observe from.

The other way is to look at the apparent magnitude of the star (i.e. what brightness it appears to be) in comparison with its absolute magnitude (i.e. what brightness it actually is, which is determined by the type of star that it is). The brightness drops off as the star gets further away.

Answer 4

How can scientist see mild years away? : this is a dumb question. with out realising it, your bare pair of eyes (under perfect circumstances with '0' city-lights furniture to mild up the exterior) you will locate 1000000000 mild years. If the products are a million situations extra luminous you will locate them too. enable's no longer get into 'expansion' of Universe, Hubble's paintings & postulates and all that. the invention is approximately that the article being considered is a million or ten million mild years away. Telescopes by potential of amassing extra mild than what a human eye scholar can do have delivered out some extra (a million situations extra) products that a human eye can purely detect (see) as dark unlit sky. Or degree that some distance? : over the years (for the final century & a 0.5) a bunch of concepts have been (see different solutions) progressed, sophisticated & mastered that it turns right into a ordinary activity for an Astronomer to "degree that some distance". Such celeb is approximately a million,000 lightyears away, with a view to locate that estimate wouldnt it take us 2,000 lightyears to get comments? : Your question presupposes sending a mild or Radio (Radar) sign to there and anticipate it to bounce back to realize us. The technical issues in touch are too in touch and unsurmountable at situations. with out your presupposition even, the mild we acquire from a definite merchandise is a 'mine' of suggestions from which we are able to get all the suggestions. The Electromagnetic spectrum (in one length) is great. The everyday element (none has guessed how some distance it might increase on the two facets) itself spans around 30 octaves (an Octave is a ratio of two:a million) of which the seen element (unfold as VIBGYOR, first by potential of Newton) is hardly an Octave. approximately ninety 9% of (mild)suggestions we've has been won by using this slender window. Radio waves too are EM waves with which it shares many useful factors the 1st of them being the 'speed' (of sunshine) that people are so prepared on quoting as 186,000 miles/2d jointly as we, the plebeians say 3 hundred,000,000 metres/2d.

Answer 5

Another way to gauge distance to galaxies (and stars, by extension) is to measure the luminosity of a Cepheid variable. Absolute luminosity is directly proportional to the periodicity of the variable, thus the distance can be determined by the apparent luminosity.

Answer 6

Doppler Affect and Luminosity.

And yes, the speed of an object can tell us how far something is since objects farther away move faster. Therefore you can easily derive an equation given one or the other.

Answer 7

1. Stellar Parallax measurements

2. Interferonomy

The doppler effect (Red shift) also helps

Answer 8

Red shift is one clue. The other is the color of the star's light and how bright it is. I could give you the math formulas but it would your brain might explode.

Answer 9

We can bounce radar waves off the Moon and the nearby planets., The sound waves emitted by the PULSAR are pushed closer together by its motion,
THAT i read in a book radar waves,be interesting to know the other.

Answer 10

they do it in light year as they can calculate the speed of light. uor closest star the sun is apporoximatly 8 mins away