<p>The obvious answer is to use a telephoto lens -- or any other magnification scheme.  As an extreme example, if you had a post 1 km tall, the shadow of its top (think sundial) would move pretty clearly.  If you re-image a short post, or just re-image the sun itself, which enough magnification, you'll see the motion.  </p>

<p>This is kind of the same as trying to observe a celestical object with a high-power telescope. If you don't have an equatorial mount, everything in your field of view will move quite noticeablly.</p>

CC BY-SA 3.0
2017-01-04T14:32:05.733Z
What do you mean by re-image? Project object's light onto a screen?
Ruslan
CC BY-SA 3.0
2017-01-04T15:20:25.230Z
Sure. Or project onto anything you want :-)
Carl Witthoft
CC BY-SA 3.0
2017-01-05T13:12:49.123Z
OK, just tried with a newly-purchased telescope. The image of the Sun on the ceiling, with diameter of the image of about 30 cm, is indeed quite visibly moving, despite all the noise of atmospheric refraction.
Ruslan
CC BY-SA 3.0
2017-01-05T13:41:01.930Z
Good to hear.  Now all you need is a video recording of the image :-)
Carl Witthoft
CC BY-SA 3.0
2017-01-05T14:16:05.183Z
I do have recorded it, but the quality is poor, since it's done with a Nokia N95's camera in a hurry 30 minutes before sunset :). If you really want to have a look, [here it is](https://youtu.be/Gfrw7YHZlbY).
Ruslan
CC BY-SA 3.0
2017-01-04T13:43:38.603Z
2017-01-04T13:43:38.603Z
Carl Witthoft
<p>Another way that can be cheaper than getting a telescope or a telephoto lens is to view the Sun almost directly: using eclipse glasses. Stand in such a way that the solar disk is partially behind a building, a road sign or a similar fixed object with a sharp edge. Make sure the object is far enough away, like a dozen of meters, to avoid parallax shifts due to slight movements of your head. Look through the eclipse glasses, and you should be able to notice the motion.</p>
<p>Even easier, without any equipment at all, is to watch the Moon instead of the Sun. The process is the same as described above, but without any glasses, since the Moon is safe to watch with the naked eyes.</p>

CC BY-SA 4.0
2023-04-18T16:18:41.490Z
2023-04-18T18:31:19.360Z
2023-04-18T18:31:19.360Z
Ruslan
<p>Each time I look at a shadow cast by a sunlit object it seems as if the shadow doesn't move at all. But if I look at it after say 5 minutes, I can notice that the shadow has actually moved a bit. This allows to say "yes, the Sun has moved in the sky". But this doesn't make it all that obvious that "the Sun is continuously moving all the time".</p>

<p>So I'd like to make some optical configuration which would allow me to watch a spot of sunlight or a shadow moving much faster — say, 1 mm/s — still being from the Sun, not from an artificial light source. I've tried doing this with a cylindrical silvery surface like that of a kitchen rail system, sticking black tape on it and leaving only a lateral strip of reflecting surface, then then letting Sun rays to hit it almost tangentially, and to observe the reflection. But either this doesn't give good enough magnification to make Sun's motion apparent, or the reflected spot just becomes too faint for the naked eye.</p>

<p>So, what can I do to effectively magnify angular motion of the Sun to observe it (almost) directly at the scale of seconds? I's OK if it could be visible for e.g. a minute and required me to adjust my instrument to view the next piece of motion. But I'd like to do it as simply as possible, without too expensive hardware.</p>

<the-sun><amateur-observing><apparent-motion>
How to make motion of the Sun more apparent at seconds scale?
Ruslan
# How to make motion of the Sun more apparent at seconds scale?

(Asked by: username_0 on 2017-01-04)

Each time I look at a shadow cast by a sunlit object it seems as if the shadow doesn't move at all. But if I look at it after say 5 minutes, I can notice that the shadow has actually moved a bit. This allows to say "yes, the Sun has moved in the sky". But this doesn't make it all that obvious that "the Sun is continuously moving all the time".

So I'd like to make some optical configuration which would allow me to watch a spot of sunlight or a shadow moving much faster — say, 1 mm/s — still being from the Sun, not from an artificial light source. I've tried doing this with a cylindrical silvery surface like that of a kitchen rail system, sticking black tape on it and leaving only a lateral strip of reflecting surface, then then letting Sun rays to hit it almost tangentially, and to observe the reflection. But either this doesn't give good enough magnification to make Sun's motion apparent, or the reflected spot just becomes too faint for the naked eye.

So, what can I do to effectively magnify angular motion of the Sun to observe it (almost) directly at the scale of seconds? I's OK if it could be visible for e.g. a minute and required me to adjust my instrument to view the next piece of motion. But I'd like to do it as simply as possible, without too expensive hardware.

**Tags:** the-sun, amateur-observing, apparent-motion


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## 2 answers

### Answer by username_1 on 2017-01-04. Score: 3 | Accepted answer

The obvious answer is to use a telephoto lens -- or any other magnification scheme. As an extreme example, if you had a post 1 km tall, the shadow of its top (think sundial) would move pretty clearly. If you re-image a short post, or just re-image the sun itself, which enough magnification, you'll see the motion.

This is kind of the same as trying to observe a celestical object with a high-power telescope. If you don't have an equatorial mount, everything in your field of view will move quite noticeablly.

> **Comments:**
> **username_0**: What do you mean by re-image? Project object's light onto a screen?  
> **username_1**: Sure. Or project onto anything you want :-)  
> **username_0**: OK, just tried with a newly-purchased telescope. The image of the Sun on the ceiling, with diameter of the image of about 30 cm, is indeed quite visibly moving, despite all the noise of atmospheric refraction.  
> **username_1**: Good to hear.  Now all you need is a video recording of the image :-)  
> **username_0**: I do have recorded it, but the quality is poor, since it's done with a Nokia N95's camera in a hurry 30 minutes before sunset :). If you really want to have a look, [here it is](https://youtu.be/Gfrw7YHZlbY).  

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### Answer by username_0 on 2023-04-18. Score: 4

Another way that can be cheaper than getting a telescope or a telephoto lens is to view the Sun almost directly: using eclipse glasses. Stand in such a way that the solar disk is partially behind a building, a road sign or a similar fixed object with a sharp edge. Make sure the object is far enough away, like a dozen of meters, to avoid parallax shifts due to slight movements of your head. Look through the eclipse glasses, and you should be able to notice the motion.

Even easier, without any equipment at all, is to watch the Moon instead of the Sun. The process is the same as described above, but without any glasses, since the Moon is safe to watch with the naked eyes.


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