Hey. Tried searching for this but was unsuccessful.
Now, to preface this, I know absolutely nothing about science. I’ve watched a few documentaries, but that’s as far as my knowledge goes.
I have been wondering about something for a while but whenever I try looking it up, the answers are far too complex for me to understand.
So my question revolves around stars. First, how is distance to stars measured? How do we know that it is reasonably accurate, and not a situation where said star was smaller and closer or bigger and farther away than previously thought?
Second, how is the brightness measured? I’ve heard stuff like “this and that star shines 100x brighter than our sun”. How can that be reasonably accurately measured over the vast distances we’re talking about in space?
Third, how can we measure or calculate mass of a star, given the vast distances?
I suspect those 3 questions might be somewhat linked, so I thought I’d ask all 3 in the same thread.
Now keep in mind, I do not understand calculus or math above algebra, so if anything like that is needed to understand, please dumb it down as much as you reasonably can.
Thankful for any replies helping me wrap my head around these concepts. Thanks in advace!
In: 9
>First, how is distance to stars measured?
For closer stars, we measure their apparent position against the background at different times of the year. Based on the diameter of Earth’s orbit, astronomers can use trigonometry to calculate the star’s position.
>How do we know that it is reasonably accurate, and not a situation where said star was smaller and closer or bigger and farther away than previously thought?
Astronomers use red-shift to calculate distance to farther objects. Since the universe expands at a known rate, objects at certain distances open at particular speeds, which produce certain amounts of redshift.
Knowing the average redshift at particular distances, combined with knowing a star’s composition (see below), and accounting for redshift of its neighbors, scientists can estimate distance and motion of very distant objects.
>Second, how is the brightness measured?
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Knowing what a star is made of (see below) gives us an idea of its mass and how much light it should emit. Physics very clearly lays out what kind of characteristics a star’s matter composition yields.
>Third, how can we measure or calculate mass of a star, given the vast distances?
>
When hot, matter emits light that is absent specific colours depending on its elemental composition. Every element has its own spectral signature. These signatures persist even if the star’s light is redshifted.
Astronomers use these color signatures to determine what a star is composed of, knowledge physicists then use to determine its mass. Stars of certain elements must be of a certain size to actually exist as stars. Measuring the redshift of a star of known composition gives its distsnce.
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