FAR SIDE OF THE MOON

[ka9q]

It's pretty cool though. The camera is parked at L1 pointing back at Earth from circa a million miles out.

I know I've seen that clip, but I don't remember when it was taken. If DISCOVR was precisely at the L1 point, that would suggest that a total eclipse of the sun occurred. (The moon does cross in front of the sun glint on the earth behind it.)

But spacecraft are never parked precisely at L1 because that would put them in the center of the sun's disc as seen from earth, and that greatly increases the radio noise seen by the ground antennas. Instead they follow a "halo" orbit around L1 in which the spacecraft appears to closely circle the sun over the course of a year.

[ka9q]

By the way, Dr Robert Farquhar, who probably did more than anybody to analyze and promote the use of the libration points (especially L1) by spacecraft, passed away on Sunday. At least I had the honor to meet him last year during the ISEE-3 Reboot Project.

https://en.wikipedia.org/wiki/Robert_W._Farquhar

[Ishkabibble]

All right, I'm just going to give up on proper attribution at this point.  From now on, everyone who isn't me will be called Bob.  Except for Bob. 

Wait, what? What's my uncle got to do with this?

 

[ka9q]

By the way, Dr Robert Farquhar, who probably did more than anybody to analyze and promote the use of the libration points (especially L1) by spacecraft, passed away on Sunday.

Here's a picture of Dr Farquhar and me, taken August 2014 during the ISEE-3 flyby of the Earth-Moon system. (That's Dr. Farquhar on the right. And I now have my hair back.)

https://www.facebook.com/photo.php?fbid=10152829930331486

[Jason Thompson]

You make the same mistake as the rest of their comrades in astrophotography these tricks with the focus not work, you can not make the planet that is in the background looks larger than the one in the foreground

Tarkus, I had some time, so here's some data for you. I collated some easily located data on planetary distances and apparent size. The first two columns contain data on the perihelion and aphelion for each planet in the solar system. The next two show the minimum and maximum separation between each planet and Earth, calculated by simple addition or subtraction of the perihelion and aphelion data. Then we have data on the apparent sizes of the planets when observed from Earth. Finally, the columns in red show the ratio between maximum and minimum separation and maximum and minimum apparent size.



Firstly the data on the apparent sizes of the planets when viewed from Earth contradicts your statement that you can't have a planet in the background looking bigger than one in the foreground when astronomical distances are concerned. You'll notice, for example, that Mars always appears smaller than Jupiter despite being significantly closer to Earth at all times, that Venus does appear larger than Jupiter when at closest approach but appears significantly smaller when at maximum separation from Earth even though it is still 'in the foreground', and Mercury, the closest of all, always appears smaller than Jupiter and Saturn. This, by the way, is something I and several others have personally verified by looking at these planets through telescopes with our own eyes: it is not a result of playing with photographic equipment.

Question 1: Given this, do you still maintain it is impossible for an object in the background to appear larger than one in the foreground?

Secondly, the numbers in red show a clear relationship between distance and apparent size. For example, Venus is nearly seven times closer at closest approach and it appears 7 times larger. This relationship is the same, and the range over which it applies shows it is linear. In other words, if you get twice as close, something will appear twice as large, and if you get twice as far away, something will appear half the size. This relationship also clearly applies at astronomical distances, as here it is derived from astronomical observations of the planets that anyone can make with their own eyes and a telescope.

Question 2: Given this, and that Earth appears to be 2 degrees wide from 400,000km away, how big will it appear from twice as far away, at 800,000km?

Two simple questions. Will you provide two simple answers? If not, why not?

[Edited to correct an error in the first question that is neatly captured by the quoted version later on...]

[onebigmonkey]

This relationship also clearly applies at astronomical distances, as here it is derived from astronomical observations of the planets that anyone can make with their own eyes and a telescope.

Don't even need a telescope - it was glaringly obvious at 6am this morning when I set out to work on my bike.

[bknight]

You make the same mistake as the rest of their comrades in astrophotography these tricks with the focus not work, you can not make the planet that is in the background looks larger than the one in the foreground

Tarkus, I had some time, so here's some data for you. I collated some easily located data on planetary distances and apparent size. The first two columns contain data on the perihelion and aphelion for each planet in the solar system. The next two show the minimum and maximum separation between each planet and Earth, calculated by simple addition or subtraction of the perihelion and aphelion data. Then we have data on the apparent sizes of the planets when observed from Earth. Finally, the columns in red show the ratio between maximum and minimum separation and maximum and minimum apparent size.



Firstly the data on the apparent sizes of the planets when viewed from Earth contradicts your statement that you can't have a planet in the background looking bigger than one in the foreground when astronomical distances are concerned. You'll notice, for example, that Mars always appears smaller than Jupiter despite being significantly closer to Earth at all times, that Venus does appear larger than Jupiter when at closest approach but appears significantly smaller when at maximum separation from Earth even though it is still 'in the foreground', and Mercury, the closest of all, always appears smaller than Jupiter and Saturn. This, by the way, is something I and several others have personally verified by looking at these planets through telescopes with our own eyes: it is not a result of playing with photographic equipment.

Question 1: Given this, do you still maintain it is impossible for an object in the background to appear larger than one on the background?

Secondly, the numbers in red show a clear relationship between distance and apparent size. For example, Venus is nearly seven times closer at closest approach and it appears 7 times larger. This relationship is the same, and the range over which it applies shows it is linear. In other words, if you get twice as close, something will appear twice as large, and if you get twice as far away, something will appear half the size. This relationship also clearly applies at astronomical distances, as here it is derived from astronomical observations of the planets that anyone can make with their own eyes and a telescope.

Question 2: Given this, and that Earth appears to be 2 degrees wide from 400,000km away, how big will it appear from twice as far away, at 800,000km?

Two simple questions. Will you provide two simple answers? If not, why not?

Nice comparisons.

[tarkus]

You make the same mistake as the rest of their comrades in astrophotography these tricks with the focus not work, you can not make the planet that is in the background looks larger than the one in the foreground, and much unless a spacecraft is able to perform such tricks, as well, why do such a thing? only is a poor way to not accept the obvious: that animation is horrifying.

So you still think that a Moon in front of a planet will always look bigger than the planet?
Explain this image then?



Two of Jupiter's moons in front of Jupiter (you can tell they are in front as their shadows are on Jupiter's surface).  Why do the moons look SMALLER than Jupiter even though they are closer to us on Earth than Jupiter is?  Do you accept that if were you hovering close to one of those moons surfaces that the moon would look big and Jupiter (relatively!) small.  It's all down to basic geometry again - please go and buy an introduction to geometry book. And while you are there you could buy a beginners guide to photography so you can learn about focus, focal length and exposure. Perhaps the college library has some books you could borrow?

No, I do not speak of "a moon" but "Moon" Jupiter's moons are very small relative to the planet, they are not a comparable case. And the debate about whether it is possible or not the focal trick is endless, in any case the question is what would a probe such manipulation ... getting smaller and darker to the Moon:



NASA used the same horrible image of Google Moon for animation.
And although it seems joke, NASA collaborates in this way in the confusion between "far side" and "dark side".

[JayUtah]

And the debate about whether it is possible or not the focal trick is endless...

Every debate with you is endless because you simply ignore or sidestep everything that proves you wrong.  Do you seriously think other people can't see what you choose to ignore?

You've been shown demonstrations that thoroughly disprove what you claim would be the case.  Do you even pay attention them?

[tarkus]

The first image is from the Apollo 15 Metric Mapping Camera:

http://www.lpi.usra.edu/resources/apollo/catalog/metric/revolution/?AS16RTE

Number 3021 to be precise, taken after TEI.

As Tarkus can find out when TEI was, he can find out where the lunar terminator should be.

You can make a start on that little mission on this page of mine:

http://onebigmonkey.com/apollo/sides/sideways.html

Where I have used the image in question.

As it was after TEI, it also will bear no relation to the terminator's position during the surface based part of the mission.

Another slight problem Tarkus has is that he is supplying an image taken by Apollo in a position that can only have been done in the proximity of the moon to prove that Apollo was nowhere near the moon.

Duh!

As for the garbage about the view of Earth, the clouds do move:



The hurricane in that was a weather feature observed from LEO satellites too.

Tarkus' contention that the moon is the wrong size is provably false, and easily done with all sorts of free astronomical software

Try again.

Thanks for the link to the mosaic of images taken by the Apollo 16, he had not seen. A little serious because about half of the images work are "burned" ... what happened?



I asked this question but I saw the answer: why the hidden face was lit during the Apollo 16 mission?

[AtomicDog]

Never picked up a camera, have you?

[bknight]

You make the same mistake as the rest of their comrades in astrophotography these tricks with the focus not work, you can not make the planet that is in the background looks larger than the one in the foreground, and much unless a spacecraft is able to perform such tricks, as well, why do such a thing? only is a poor way to not accept the obvious: that animation is horrifying.

So you still think that a Moon in front of a planet will always look bigger than the planet?
Explain this image then?



Two of Jupiter's moons in front of Jupiter (you can tell they are in front as their shadows are on Jupiter's surface).  Why do the moons look SMALLER than Jupiter even though they are closer to us on Earth than Jupiter is?  Do you accept that if were you hovering close to one of those moons surfaces that the moon would look big and Jupiter (relatively!) small.  It's all down to basic geometry again - please go and buy an introduction to geometry book. And while you are there you could buy a beginners guide to photography so you can learn about focus, focal length and exposure. Perhaps the college library has some books you could borrow?

No, I do not speak of "a moon" but "Moon" Jupiter's moons are very small relative to the planet, they are not a comparable case. And the debate about whether it is possible or not the focal trick is endless, in any case the question is what would a probe such manipulation ... getting smaller and darker to the Moon:



NASA used the same horrible image of Google Moon for animation.
And although it seems joke, NASA collaborates in this way in the confusion between "far side" and "dark side".

Moved those goal posts again, tarkus face it as one moves away from the moon as you described in one of your posts the relative angular sizes can be computed and you will find that yes the moon being in the foreground will be smaller than the earth in the background.  It is simple trig. nothing fancy  the reason we have solar eclipses is the4 moon covers the sun's disk w3hile being in excess of 90 million miles from the sun.

[onebigmonkey]

I asked this question but I saw the answer: why the hidden face was lit during the Apollo 16 mission?

Seriously, really??

Because this happens, every month:

[Jason Thompson]

And the debate about whether it is possible or not the focal trick is endless,

Tarkus, it is not a focal trick, it is a simple case of perspective. I notice your failure to address the table of actual data I provided. Why would that be?

[ka9q]

No, I do not speak of "a moon" but "Moon" Jupiter's moons are very small relative to the planet, they are not a comparable case.

Sure it's comparable! All of Jupiter's moons are smaller than the planet, and our one moon is smaller than our planet. If it wasn't, it would be the planet and we would be on its moon.

Only you seem to be confused about the distinction between the "far" and "dark" sides of the moon. In the DISCOVR pictures, taken from the direction of the Sun, we see our moon just as it is beginning another cycle (from "old" to "new" moon). At that time the "far side" (from the earth) faces DISCOVR and is fully lit, just like the earth behind it. The "dark side" of the moon at that time is the "near side" that always faces the earth, but which faces away from DISCOVR in this photograph.

And yes, the relative brightness is correct. The moon is much darker than the earth; it has no atmosphere, clouds or bodies of water to scatter and reflect sunlight.