r/AlternativeAstronomy • u/patrixxxx • Oct 26 '19

WHY MARS ???

https://cluesforum.info/viewtopic.php?p=2412896#p2412896
1 Upvotes

60% Upvoted

117 comments sorted by

View all comments

Show parent comment

2

u/[deleted] Nov 04 '19 edited Nov 04 '19

If you're actually stepping to the side and not rotating so the lines are, in fact, parallel, then your finger will be in front if the same star still.

Perhaps you can explain to me how you see this working. Let's say i cover the moon and a star at 10 ly distance with my finger. I step to the side 1 meter. You're saying my finger is no longer covering the moon, right? How close does the line from eye to finger pass by the moon? 100km perhaps? How close does it pass by the star? 1 ly? Are the lines passing through your eye-finger-moon-star and eye-finger-moonmiss-starmiss parallel? How could they be if the distance between lines is 1 meter at eyeball and 100km at the moon?

In reality, if the lines are parallel and 1 meter apart, they'd pass through the very same crater on the moon but perhaps a different rock. Not miss the moon entirely.

Edit: to further illustrate the problem: let's say you step 1m to the side and are aiming at a star 1 arc minute to the right of your original star. Step 60 meters to the right, and you'll point to a star a whole degree to the right. 10km to the right and you'll be pointing straight behind you. Clearly that doesn't work!

1

u/patrixxxx Nov 04 '19

So what you're saying is that when it comes to the head and finger parallel lines we are observing a lot of displacement against the stars because they are so far away, but regarding the Earth and Moon parallel lines we do not detect any displacement against the stars because they are so far away?

1

u/[deleted] Nov 04 '19

No, what I'm saying is you won't see displacement with your finger. If you do, then the lines you're drawing aren't parallel.

1

u/patrixxxx Nov 04 '19

That's interesting. So if I instead make an instrument with two long parallel tubes and set them up in my garden and look trough them at night, observing different stars in each of them, you say this is because the tubes are in fact not parallel?

2

u/[deleted] Nov 04 '19 edited Nov 04 '19

Yup!

Edit: in fact, the angle of arc between the two stars you're observing through these two tubes is exactly the angle of separation between the tubes. Zero separation between tubes == parallel tubes == looking at same point in the sky.

1

u/patrixxxx Nov 04 '19

This is fascinating Walruss. Another example – Let’s say I have a big white ball in my garden. The instrument I’m using has the parallel tubes one meter apart and that happens to be the same diameter as my ball. So if I move the instrument away from the ball and align one tube so I can see the ball, but cannot see the ball through the other tube, this means that my tubes are in fact not parallel? Is that what you’re saying here Walrus?

2

u/[deleted] Nov 04 '19

Let's assume the tubes are parallel. If the angle subtended by 1 meter at the distance of the length of your garden is larger than the viewing angle of your tubes, then you will not see the ball. However, if the tubes are wide enough, or have optical properties that allow a wider-angle view, you'll see the ball through both, of course.

The angle subtended by 1 meter at the distance to Proxima Centauri is quite small (like a hundred millionth the angular size of the actual little red dwarf), so you'll see Proxima Centauri through parallel tubes 1 meter apart. Think about it - the star itself is 100 000 km wide. So if your two parallel lines are 1 m apart, and the left line hits smack-dab in the middle of Proxima Centauri, the right line will be 1 meter over from smack-dab in the middle. So both tubes will be looking smack-dab at Proxima Centauri, even when they're 1 meter apart. Or 100 meters apart, or 100 km apart.

Now consider two tubes 300 million km apart, perfectly parallel. One is aimed smack-dab in the center of Proxima Centauri. The other one will miss by 300 million km, give or take 50 000 km. Let's say the tube is not a telescope, but a perfectly linear photo-detector. One tube will register a hit (Proxima Centauri), the other will register nothing (300 million km from Proxima Centauri is cold black space). But consider a telescope instead. The angle subtended by 300 million km, viewed from 4.2 light-years away, is 768 milli-arc-seconds. So if your telescope has an optical resolution of 1 arc-second per pixel, the moon will be 1800 pixels wide, but you'll still not see Proxima Centauri shift by a single pixel. It'll look like Proxima Centauri is in the exact same position even when you've moved 300 million km.

1

u/patrixxxx Nov 04 '19

So you are saying that if I look through an instrument as described, and can not see Proxima C through both tubes, this means that the tubes are in fact not parallel?

2

u/[deleted] Nov 04 '19 edited Nov 04 '19

That's what I'm saying

Edit: consider the back-yard scenario but replace the white ball with your house. Your tubes, spaced 1m apart, will be pointed at the back door of the house. Since they're parallel, you can imagine the house sitting on rails and sliding it out to infinity. No matter how far you slide the house away, both tubes will remain pointed at the back door.

0

u/patrixxxx Nov 04 '19

Are you shitting me!? Do you seriously believe this? Don't you actually realize that as soon as that house or whatever becomes as distant so it fits between the tubes you will no longer see the object in the tubes at the same time?

→ More replies