Calculating the size of the Sun and the Moon from angular size and distance

This demo shows how to calculate the size of the Moon and the Sun, given angular size and distance. It derives the equations necessary.

[joshuaokee]

Thank you from the bottom of my heart. This helped me so much to prep for first astronomy test

[nicolemaesugarcanes]

Thank you. This video demystified angular distance much better than my textbook.

[wrtgs]

How do you calculate x and distance if the only known variable is the angular size of the moon?

[ankitaaarya]

everyone is talking about how did he get the distance of moon, heres my clarification.
he is measuring "the actual size" or "diametre" of the moon. in order to do measure "size" you NEED the distance. point of this video is about measuring the size or diametre of the moon.
thanks you.

if i get it wrong please correct me.

[michaeltebele]

Ahh the transition from sense information to scientific fact. Beautiful

[juandavidquiros]

And where did you get that distance (384000km)? from a book?

[vaanar]

I know that moon is 0.5 degrees and Jupiter is 0.013 degrees. Now I want to know, how many Jupiter could fit in a moon. Can you please do the maths for me🥺👉👈

[Timsful]

The distance isn't known. HOW DO WE FIND THE DISTANCE?

[yhenry]

*???* Let me get this straight, we're now able to calculate the distance to the Moon at over 230, 000 miles? I also read in a leading astronomy magazine, the human naked eye can see an crater (53 miles across) on the Moon? Please, can anyone explain HOW this is possible?

"Tycho is one of the few lunar craters you can actually see with the naked eye. If you stare squarely at it, you'll see a tiny, unresolved bright spot about a quarter of the way in from the southern limb." - Sky and Telescope 2/28/18 by Bob King

[jszlauko]

Great explanation!  I was just researching the equation for determining the angular apparent size of the moon as I ran across a person on the web that thought the moon must be way closer than we think it is due to the size of it as we see it.  I knew that it could be calculated, but the equations I found seemed to be a bit confusing.  You really cleared it all up for me!  I KNOW the distance and size of the moon are accurate, but wanted to basically prove it to a person who doesn't know any better.

[shawneegeek]

This was, by far, the easiest explanation for this I have found... Thank you.

[BrianBlais]

to find "a", the angle, depends on your camera/eye piece and the zoom. many times a device will have the full field of view (in degrees) and you can calculate from there (i.e. the object is 1/2 of my 40 degree field of view, a=20 deg). Or, if you don't know what it is, take a picture of a ruler at a known (much smaller) distance, and work backwards from the above to find the full field of view. then use that to get your "a" in the cases where you don't know the distance.

[vnyeu]

why you dont explain how you get distance

[davidnnn]

How to do some angle by some angle? I want to find out the actual radius. Distance to object is given.

[anthonymoffa]

how would you find out the value of A in a real world example without it being given to you?

[blablaforhknot]

Amazing dude thanks a lot really I was not getting it but now I've mastered it haha

[mikehollis]

Hi Brian, great explanation, easy to follow.
Question, can you confirm the accuracy of the degree when viewing an object at 457 kilometers, whose diameter is apparently 10mm at arms length?
I calculated 3.84 kilometers, but could be smaller, my pinky finger is approx 15mm = 0, 5.
deg.
Should I use 0, 4 deg?
Back story as a matter of curiosity , I witnessed a cylinder rendezvous with the ISS (Space Station)
The dia was approx 10mm at arms length, it's length was +- 3 x the dia.
I know sounds weird, but there is tech up there way ahead of what we know about.
Thanks and regards, Mike.

[DemianOleg]

Hi Brian, what software are you using to write / draw?

[aeb]

This really help me, thank you so much

[thelastcipher]

i was checking if i got my method right, turns out i was using this method. the word problem from my book got me an answer that the sun's diameter is 2, 717, 163.44 miles across however if you google the sun's diameter.. it's only 900, 000 miles