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View Full Version : Who's wrong? Lightwave Mathematics or NASA?



silviotoledo
07-15-2017, 01:21 PM
Take a look at this NASA image

https://www.nasa.gov/sites/default/files/moon_and_earth_lroearthrise_frame_0.jpg

I modeled the Earth and the Moon with the correct sizes and used Lightwave lens to try to simulate the image.

Moon Radius 1.737 km
Earth Radius 6.371 km
Distance from Earth to the Moon 384.400 km

The problem is that the Moon only start to appear as some small pixels on an HD resolution when lens is 4000 mm.
Maybe the NASA picture is wrong ( fake )

So how do we see the moon from earth with our eyes ( 50 mm lens ) ?

Is the NASA/Astronomy distances incorrect or is Lightwave math incorrect?

silviotoledo
07-15-2017, 01:52 PM
137383

Dexter2999
07-15-2017, 02:19 PM
You do see that the NASA picture is one from the moon pointing at the earth? And your simulation is one from earth pointing to the moon?
The earth will obviously be larger in the NASA pic than the moon is from the earth because it is a photograph of a larger object from a smaller object.
And I wouldn't call the image "faked" but a zoom lens can seem to increase the scale of the earth (or moon) because it flattens the distance between objects and magnifies the foreground image. So you can trick the eye, like this https://www.dodho.com/wp-content/uploads/2013/11/Man-on-the-Moon-Australia-960x700.jpg

But, yeah, I think your simulation has some kinks in it.

Danner
07-15-2017, 05:27 PM
The NASA image is also a render, so they could have used any zoom they wanted. Go outside, take a picture of the moon with your phone. tell me how big it looks in that image. (spoiler: very small)

ccclarke
07-15-2017, 06:36 PM
If you want to duplicate the (non-fake) NASA image, you also need to determine the focal length of the lens used to create the original picture.

The diameters of and distances between both bodies are established facts.

This follows the time-proven rule: Garbage in = Garbage out. Configure Lightwave properly and you will be successful.

CCC

RudySchneider
07-15-2017, 10:49 PM
I'm not completely sure I understand your issue, silviotoledo, but you got my curiosity up, so I decided to do a bit of simulation myself. The Earth has a mean diameter of 7917 Miles, the moon has a diameter of 2159 miles, and is 238,900 miles away. The Apollo 8 was in a circular orbit 60 miles above the surface of the moon. So, my Earth and Moon objects are 791mm and 216mm, respectively, and I've separated them by 23.89 meters. The 60 mile orbit means the "Camera" is parented to and at (216 + 12 (60 mile above moon means 120 miles added to diameter) =) 228mm above the center of the "Moon."

Here's a 50mm focal length shot of "Earth" from "Moon's" orbit. I simply rotated the "Moon" until the "Earth" came into view.

Fun exercise.

Sensei
07-15-2017, 11:14 PM
1737 km radius * 2 = 3474 km diameter of sphere/circle

384400 km distance to the Moon * 2 * PI = 2415256 km full 360 degrees view.

3474 km / 2415256 km = 0.0014379 = 0.144% of the full 360 degrees view.
* 360 degrees = 0.517 of single degree.

RebelHill
07-16-2017, 07:05 AM
yeah... sensei's right about the angular measurement... its easiest.

If you measure the sky in degrees, the the horizon on one side to that on the other is (obviously enough) 180deg... the appearance of the moon is about 0.5 deg across... In LW, make a moon of correct size/scale, at corresponding distance, zoom your camera in till it has 0.5deg field of view... moon fills the frame.

Slartibartfast
07-16-2017, 02:25 PM
The appearent size of the moon is smaller than people think. When asked "how big is the moon compared to an object at arms length?" many people answers "like a tennisball". The fact is you can cover the moon with your little finger's nail. Which is about 0.5 degrees as previously mentioned ;-)

Dexter2999
07-16-2017, 02:38 PM
http://picayune.uclick.com/comics/ch/1989/ch890730.gif

Slartibartfast
07-16-2017, 03:17 PM
Lol!
Here is a pic I took before It set in Arizona last year. Can you spot Mercury?
137397

danielkaiser
07-16-2017, 06:26 PM
Lol!
Here is a pic I took before It set in Arizona last year. Can you spot Mercury?
137397

Upper left hand. What kind of filter, camera, and settings did you use?

Slartibartfast
07-16-2017, 11:52 PM
Upper left hand. What kind of filter, camera, and settings did you use?

That's right. Except when watching the image from my iPhone, which rotates the image. Then it's the directional kind of right. Anyways, I shot it with an iPhone through the eyepiece of a 750 mm 6" telescope with a sun filter. Can't remember wich eyepiece I used at that moment, but I think 9mm. Or 17.

50one
07-17-2017, 05:58 AM
There's also atmosphere magnifcation factor to consider...

Ernest
07-17-2017, 06:37 AM
There's also atmosphere magnifcation factor to consider...

Oh that's a good point, so what would the moon look like from above the atmosphere?
http://universe-beauty.com/Space-photos/Other/iss-moon-rise-7784p.html/(mode)/search/(keyword)/normalearth-rise
Not quite 1 pixel but it does look pretty small.

ianr
07-17-2017, 08:54 AM
ask the 'Sky @ Night' T.V. team they are preety

clued into Astro & Nasa, c/o (care of) BBC 4