4 ms·

Pick a random azimuth you want to go. Keep walking while having sun always at the same position and you'll be walking in the straight line. Pick random azimuth

by dvh 4y ago

Pick a random azimuth you want to go. Keep walking while having sun always at the same position and you'll be walking in the straight line. Pick random azimuth you want to go. Keep walking while having street lamp always at the same position and half of you will be spiraling away from the lamp, and the other half will be spiraling towards the lamp forever.

canadianfella 4y ago
[dead]
MauranKilom 4y ago
This paper specifically provides strong evidence against this explanation: > We also do not observe logarithmic spirals toward the centre of the light source, a key prediction of celestial compass entrapment.
mkl 4y ago
The key finding of the research in this article is that this is not what is happening. See the "Flight path manipulation via light switching" section and the Discussion section.
toss1 4y ago
>>Pick a random azimuth you want to go. Keep walking while having sun always at the same position and you'll be walking in the straight line. Not quite. That's a good way to get lost in a hurry. Let's pick North as our azimuth, right around sunrise in my location in New England. The sun is rising 77° to the right at 06:00, as I face North and start walking. But the sun moves in the sky, so if I keep the sun 77° to the right of my nose as I walk, by 12:15, the sun is at 167°, and I am now walking due East... I'll be walking in a curve following your guidance here, not a straight line, and the radius will depend on my walking/riding/sailing speed. The same failure occurs for the Moon or any other astronomical object other than the polestar. This is why the invention of portable accurate timepieces was so critical.
- LorenPechtel 4y ago
  It works well enough over a reasonably short duration, it doesn't work very well near sunrise/sunset. During the middle part of the day (say 10a-2p) I can be confident that if I'm walking into my shadow that I'm heading approximately north--not perfect but good enough that for gross navigation I'm not going to bother to pull out my phone and look at the map. (I would never be out in the wilderness without *having* map/GPS/satellite texting/headlamp, but that doesn't mean I always *use* them.)
  - toss1 4y ago
    Of course, on a small enough area, short enough time, and rough enough goal, it's fine. The same applies to the earth being round or flat. I don't compensate for the curvature of the earth when figuring out area of bricks for a front walk, or building a shed. So what? With your example, if I'm just trying to walk roughly north in the middle of the day and I know that my destination is just west of mountain slope that I'll see when I get near, then it'll work to just keep our shadows roughly in front of us. But, let's take finding a point on a functionally featureless plain or desert. It's 8 miles away, due North, so a bit over a two hour brisk walk. Local noon (w/DST) is 12:45, so we start at 11:45, and the sun's azimuth is 154°. By the time we get close-ish two hours later (say 7mi at 3.5mph), the sun's azimuth is 207°. So, we started out walking North, but we've been bending to the East, and are now off course by 53° to the East, and our average path is 26° off. After 2 hours at 3.5mph, we should be 1 mile away, due South, and set to arrive in 17 minutes more walking. Instead, we're 3.2 miles away from our objective, and walking 53° in the wrong direction. The zone where this works is really pretty small, and we're probably using landmarks instead. And if you're trying to do this on water without compensating for the earth's rotation, you'll soon be in trouble...
    - LorenPechtel 4y ago
      It's not nearly that bad. You start heading too far east and bend back. After your two hours you are exactly on the right direction but have gone a bit farther than you needed to and are 26 degrees off course. I've never encountered any large, featureless terrain; rarely am I moving in a direction that's not either with the nature of the terrain or nearly directly across the terrain--it's easier to go a bit farther while minimizing the terrain fighting.
NoPicklez 4y ago
I read this too and they went on to say the following. Other mechanisms might contribute to the arrival of insects at nocturnal light sources over longer ranges. For instance, insects do use celestial compasses for nocturnal navigation, and artificial light sources may interfere with these heading cues. But even at long distances artificial light sources often remain brighter than the night sky and may cause dorsal tilting that would also steer an insect towards a light source. But I thought I interpreted their earlier point that this isn't the reason they're drawn the light. I recently read a book which said that Moths use the moon for the navigation and artificial light throws off that process, becoming entrapped.

by dvh 4y ago

canadianfella 4y ago

[dead]

MauranKilom 4y ago

This paper specifically provides strong evidence against this explanation: > We also do not observe logarithmic spirals toward the centre of the light source, a key prediction of celestial compass entrapment.

mkl 4y ago

The key finding of the research in this article is that this is not what is happening. See the "Flight path manipulation via light switching" section and the Discussion section.

toss1 4y ago

>>Pick a random azimuth you want to go. Keep walking while having sun always at the same position and you'll be walking in the straight line. Not quite. That's a good way to get lost in a hurry. Let's pick North as our azimuth, right around sunrise in my location in New England. The sun is rising 77° to the right at 06:00, as I face North and start walking. But the sun moves in the sky, so if I keep the sun 77° to the right of my nose as I walk, by 12:15, the sun is at 167°, and I am now walking due East... I'll be walking in a curve following your guidance here, not a straight line, and the radius will depend on my walking/riding/sailing speed. The same failure occurs for the Moon or any other astronomical object other than the polestar. This is why the invention of portable accurate timepieces was so critical.

LorenPechtel 4y ago
It works well enough over a reasonably short duration, it doesn't work very well near sunrise/sunset. During the middle part of the day (say 10a-2p) I can be confident that if I'm walking into my shadow that I'm heading approximately north--not perfect but good enough that for gross navigation I'm not going to bother to pull out my phone and look at the map. (I would never be out in the wilderness without *having* map/GPS/satellite texting/headlamp, but that doesn't mean I always *use* them.)
- toss1 4y ago
  Of course, on a small enough area, short enough time, and rough enough goal, it's fine. The same applies to the earth being round or flat. I don't compensate for the curvature of the earth when figuring out area of bricks for a front walk, or building a shed. So what? With your example, if I'm just trying to walk roughly north in the middle of the day and I know that my destination is just west of mountain slope that I'll see when I get near, then it'll work to just keep our shadows roughly in front of us. But, let's take finding a point on a functionally featureless plain or desert. It's 8 miles away, due North, so a bit over a two hour brisk walk. Local noon (w/DST) is 12:45, so we start at 11:45, and the sun's azimuth is 154°. By the time we get close-ish two hours later (say 7mi at 3.5mph), the sun's azimuth is 207°. So, we started out walking North, but we've been bending to the East, and are now off course by 53° to the East, and our average path is 26° off. After 2 hours at 3.5mph, we should be 1 mile away, due South, and set to arrive in 17 minutes more walking. Instead, we're 3.2 miles away from our objective, and walking 53° in the wrong direction. The zone where this works is really pretty small, and we're probably using landmarks instead. And if you're trying to do this on water without compensating for the earth's rotation, you'll soon be in trouble...
  - LorenPechtel 4y ago
    It's not nearly that bad. You start heading too far east and bend back. After your two hours you are exactly on the right direction but have gone a bit farther than you needed to and are 26 degrees off course. I've never encountered any large, featureless terrain; rarely am I moving in a direction that's not either with the nature of the terrain or nearly directly across the terrain--it's easier to go a bit farther while minimizing the terrain fighting.

NoPicklez 4y ago

I read this too and they went on to say the following. Other mechanisms might contribute to the arrival of insects at nocturnal light sources over longer ranges. For instance, insects do use celestial compasses for nocturnal navigation, and artificial light sources may interfere with these heading cues. But even at long distances artificial light sources often remain brighter than the night sky and may cause dorsal tilting that would also steer an insect towards a light source. But I thought I interpreted their earlier point that this isn't the reason they're drawn the light. I recently read a book which said that Moths use the moon for the navigation and artificial light throws off that process, becoming entrapped.