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
Hold your finger out in front of you, sticking straight up. Look at it. Now close your right eye. Still see it? Now close your right eye and open your left eye at the same time. See it move? Keep doing that.
Camera one, camera two. Camera one, camera two.
This effect is called “parallax”. The position of the thing you’re looking at seems to move based on the angle you’re seeing it from. Instead of looking at your finger, if you look at something across the street, it won’t appear to move as much. The difference in angle isn’t as big. If you look at something really really far away (like a mountain range, or the Moon), it won’t appear to move at all. This is very obvious if you hold up your finger, and behind that finger you can see the house across the street, and behind that house you can see a mountain range in the background. Now when you do it, your finger seems to move a lot, the house only a little, and the mountain not at all.
We can do the same “camera one, camera two” trick from Earth, when looking at the stars. But to make the angle as big as possible, you need a lot of distance. The easiest way to do that is to wait six months. In June, the Earth is on one side of the Sun. In December, it’s all the way on the other side of the Sun. So you take pictures six months apart, and compare them, and see which stars have moved and by how much.
Stars that are closer to us will appear to move a lot more than stars that are farther away. For closer stars, we can use trigonometry to measure their distance. We know how much they appeared to move, and we know how far away they would need to be to move that same amount. The better your telescopes, the more precise your measurements, and the better your distance calculations can be.
We have done this *a lot*. Lots of people and lots of telescopes, and everybody checking each other’s work to make sure they didn’t screw up. Lots and lots, on every star even kind of close enough to measure.
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