How is star distance, brightness and mass calculated/measured?

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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!

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8 Answers

Anonymous 0 Comments

Astronomers use an effect called parallax to measure distances to nearby stars. Parallax is the apparent displacement of an object because of a change in the observer’s point of view.

the brightness of these stars using the magnitude scale. The magnitude scale seems a little backwards. The lower the number, the brighter the object is; and the higher the number, the dimmer it is. This scale is logarithmic and set so that every 5 steps up equals a 100 times decrease in brightness.

The formula 𝑀 = 4𝜋²𝑟³/𝐺𝑇² can be used to calculate the mass, 𝑀, of a planet or star given the orbital period, 𝑇, and orbital radius, 𝑟, of an object that is moving along a circular orbit around it.

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