<p><a href="https://sciences.utsa.edu/physics-astronomy/eclipse.html" rel="nofollow noreferrer">This webpage</a> answers my question completely. Even a 99.9% block of the sun belongs to a partial eclipse, you can not experience any of the following:</p>
<ul>
<li>temperature &amp; wind changes</li>
<li>dramatic brightness changes</li>
<li>sunset colors around horizon</li>
<li>bright stars and planets</li>
<li>corona, diamond ring effects, and others</li>
</ul>
<p>So a 99.9% eclipse will not be enough at all. You need a 100% eclipse to enjoy those experiences.</p>

CC BY-SA 4.0
2024-03-24T00:24:33.140Z
@EZhang *Welcome to Stack Exchange!* It's always OK to answer your own question, and to accept the answer if it's the best one. However we really avoid *changing the question* once answers start to be posted. Try to avoid doing that in the future, *thanks!*
uhoh
CC BY-SA 4.0
2024-03-24T00:38:20.447Z
@EZhang I also find it frustrating when answers suggest the question is not the right question to ask. It happens occasionally, I just ignore it. Sometimes answer posts are written more for the benefit of future readers, or general interest, than they are the question author's specific interest. I call this [uhoh's lemma #3](https://meta.stackexchange.com/q/377004/303080) Stack Exchange is BOTH a floor wax, AND a desert topping :-)
uhoh
CC BY-SA 4.0
2024-03-22T19:40:29.987Z
This may be the answer you wanted, but it is not an actual answer to your *stated question* of what "night hour" or "evening/morning hour" has equivalent darkness. My [answer](https://astronomy.stackexchange.com/a/57234/32118) does address that.
nanoman
CC BY-SA 4.0
2024-03-23T01:33:06.507Z
No, it answers exactly what I want to know. It says that no dramatic brightness changes, no sunset colors around the horizon, and no bright stars and planets under the 99.9% eclipse, which means people can not really experience the change of daylight and night even under the 99.9% eclipse.
E Zhang
CC BY-SA 4.0
2024-03-22T18:34:30.470Z
2024-03-22T18:34:30.470Z
E Zhang
<p>I agree with James K's observation that the main point of a total eclipse is not the darkness but the visibility of the corona.</p>
<p>However, to answer your original question, blocking 99.5% of the Sun* would reduce the daytime <a href="https://en.wikipedia.org/wiki/Lux#Illuminance" rel="noreferrer">illuminance</a> by a factor of 200, roughly from 20,000 lux (full <a href="https://en.wikipedia.org/wiki/Daylight" rel="noreferrer">daylight</a>) to 100 lux. Even so, this would not feel very dark, because our eyes have a very wide dynamic range.</p>
<p>At dawn or dusk (in the absence of an eclipse), natural illuminance of 100 lux occurs during <a href="https://glossary.ametsoc.org/wiki/Civil_twilight" rel="noreferrer">civil twilight</a> shortly before sunrise or shortly after sunset. You can still see well. For additional context, this is <a href="https://en.wikipedia.org/wiki/Lux#Illuminance" rel="noreferrer">comparable</a> to a day with very heavy overcast clouds, or to the indoor lighting in an office building.</p>
<p>So the change in general brightness during a 99.5% eclipse is noticeable, but not dramatic. Even if the eclipse is covered by clouds, there would be a much bigger perceived change in brightness where the eclipse is total. And if the eclipse can be viewed clearly, then of course there is no comparison.</p>
<p>* A technicality: The most commonly quoted measure of a partial eclipse, the &quot;magnitude&quot;, is the maximum fraction of the Sun's apparent <em>diameter</em> (not <em>area</em>) that is covered by the Moon. So for a precise answer, you would need to ensure which number you read. I will assume here that 99.5% is the fraction of area, known as the &quot;obscuration&quot;. The issue does not affect the qualitative conclusions.</p>

CC BY-SA 4.0
2024-03-22T19:38:22.470Z
2024-03-22T19:38:22.470Z
nanoman
<p>This misses the point.</p>
<p>During totality the sun's corona becomes visible. If any part of the photosphere is exposed, then the corona isn't visible.</p>
<p>The experience of a total eclipse is not just &quot;darkness&quot; (you get about 12 hours of that every day!) It is the ring of the solar corona.</p>
<p>To answer your question, 99.5% of the sun is obscured a few seconds before sunset. But this isn't a fair comparison since at sunset the sun is obscured by the Earth which is inside the atmosphere, and during an eclipse the sun is obscured by the moon, which is beyond the atmosphere.</p>
<p>My granddad used to say &quot;a miss is as good as a mile&quot; If the sun is not covered by the moon, it is a partial eclipse and those are pretty common.  You will only experience totality if the sun is covered by the moon. 99.5 % is not totality and is a completely different thing.</p>

CC BY-SA 4.0
2024-03-23T16:02:49.977Z
@Greg Miller, James' answer is not enough. As I explained, the change of twilight is slow. I want to experience a quick turn from daylight to evening. I found a webpage that perfectly answers my question. So I answered it in a post.
E Zhang
CC BY-SA 4.0
2024-03-23T18:27:35.293Z
@EZhang The covering of sun by the horizon at sunset is caused by the earth's rotation (once per day). The covering of the sun by the moon during a solar eclipse is caused by the moon's revolution (once per month). So the transition from light to dark is about 28 times *slower* during a solar eclipse than during a sunset.
Greg Martin
CC BY-SA 4.0
2024-03-23T21:50:13.123Z
@GregMartin That would be true if sunset darkness were purely a function of geometric occlusion of the Sun -- e.g., if the Earth had no atmosphere. In reality, there is of course a long, gradually dimming twilight after sunset. Though the Sun appears to set quickly (crossing over the horizon in a few minutes), this does not immediately produce a big change in overall illuminance because so much of the setting Sun's light is scattered by the atmosphere. The sky as a whole is almost as bright just after sunset as just before. Compared to this, the final darkening of a total eclipse is rapid.
nanoman
CC BY-SA 4.0
2024-03-22T17:39:57.237Z
This does not answer my question. I do not care whether I can see the solar corona with the naked eye or not because I have an eclipse glass. Nor do I care if it is obscured by the Earth's atmosphere or others. I just want to know if the 99.5% blocked sun would like a night, or closer to nightlight than daylight. For me, the most important thing is to experience a sudden change to the night environment from daylight.
E Zhang
CC BY-SA 4.0
2024-03-22T17:54:55.777Z
I've edited. If all you care about is the change from light to dark, I suggest you go out at between 6 and 7 pm then.  You will experience a change from day to night.  Or go out between 5  and 6 am.  You will experience a change from night to day.  These are not special.  If you are not in totality you are not experiencing a total solar eclipse. And, frankly, who cares about a partial eclipse?  Those happen every couple of years.  Totality is special.  99.5% is rubbish by comparison.
James K
CC BY-SA 4.0
2024-03-22T18:09:57.427Z
The change of light at sunset/sunrise takes some time. In a total eclipse the change is much quicker I think. Put in another perspective, can stars be seen under the 99.5% block of the sun? I know they can be seen under 100% block of the sun. Is 99.5% still belonged to partial eclipse?
E Zhang
CC BY-SA 4.0
2024-03-22T18:17:59.710Z
Feel free to self answer.
James K
CC BY-SA 4.0
2024-03-22T19:10:59.653Z
@EZhang you state in your question that "there is no need travel to a place where the sun is 100% blocked".  James' answer explains why that's not the case.  If all you want to see is darkness, just wait until night time.
Greg Miller
CC BY-SA 4.0
2024-03-22T19:47:38.610Z
@EZhang "can stars be seen under the 99.5% block of the sun?" -- no, see my answer -- bright stars become just visible at the dark end of [civil twilight](https://glossary.ametsoc.org/wiki/Civil_twilight), with illuminance of around 3 lux, which would require 99.99% blocking.
nanoman
CC BY-SA 4.0
2024-03-22T19:51:35.830Z
@JamesK You acknowledge that considering the fraction of the Sun visible at sunset "isn't a fair comparison". Of course, this is because atmospheric scattering provides significant illuminance even when the Sun is entirely below the horizon. To this end, my [answer](https://astronomy.stackexchange.com/a/57234/32118) uses data on twilight brightness to answer OP's specific question more accurately.
nanoman
CC BY-SA 4.0
2024-03-22T20:11:27.447Z
@nanoman agree, upvoted.
James K
CC BY-SA 4.0
2024-03-22T06:52:56.430Z
2024-03-22T17:53:44.627Z
2024-03-22T17:53:44.627Z
James K
<p>There's no equivalent.  At 99.5% coverage, the overall light level is comparable to that of twilight a few minutes after sunset.  However, the majority of the light is still coming from a point source, so you get phenomena such as sharp shadows that aren't present after sunset.  The overall result is an impression of &quot;wrongness&quot; to the light, but it's nothing like the experience of totality.</p>
<p>During the 2017 eclipse, I recorded a video of the final 30 seconds before totality in an attempt to catch the Moon's shadow sweeping across the ground.  It mostly didn't work, but I did catch a phenomenon nobody had mentioned before: the crowd cheering the moment totality started.  Below is a frame from 25 seconds before the cheering, showing how a camera sees 99.5% coverage.</p>
<p><a href="https://i.sstatic.net/eIuXg.jpg" rel="noreferrer"><img src="https://i.sstatic.net/eIuXg.jpg" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2024-03-22T23:34:40.923Z
2024-03-22T23:34:40.923Z
Mark
<p>My experience with the last total eclipse was that it got noticeably dimmer and instantly cooler. It was not like night at all. I would say the level of light was probably closer to dawn, or like when a heavy cloud goes over the sun.</p>

CC BY-SA 4.0
2024-03-22T17:43:09.247Z
2024-03-22T17:43:09.247Z
foxpup
<h3>Snakes!</h3>
<p>In addition to <a href="https://astronomy.stackexchange.com/a/57235/7982">@Mark's answer</a> that everything looks &quot;wrong&quot; with a near point-like dim source (basically this is what daylight looks like at 15 AU, (between Saturn and Uranus)) there are other effects you can think about. I am not sure 99.5% coverage is enough, but when the Sun is covered except for a very, very thin sliver, atmospheric effects on Earth called &quot;shadow snakes&quot; or what Wikipedia calls <a href="https://en.wikipedia.org/wiki/Shadow_bands" rel="nofollow noreferrer">shadow bands</a> become visible.</p>
<p>Slightly related: <a href="https://astronomy.stackexchange.com/q/27226/7982">Would an extremely bright star produce same kind of shadow band effect as seen in solar eclipses just before totality?</a></p>
<p><div class="youtube-embed"><div>
                <iframe width="640px" height="395px" src="https://www.youtube.com/embed/lepQoU4oek4?start=0"></iframe>
            </div></div></p>
<p><div class="youtube-embed"><div>
                <iframe width="640px" height="395px" src="https://www.youtube.com/embed/qc7MfcKF1-s?start=0"></iframe>
            </div></div></p>

CC BY-SA 4.0
2024-03-24T00:32:58.537Z
2024-03-24T00:32:58.537Z
uhoh
<p>The eclipse as seen in Toronto, Ontario, Canada <a href="https://www.timeanddate.com/eclipse/in/canada/toronto?iso=20240408" rel="nofollow noreferrer">reached</a> a maximum magnitude of 0.998, <a href="https://trca.ca/solar-eclipse/" rel="nofollow noreferrer">reported</a> on a Toronto and Region Conservation Authority website as &quot;a magnitude of 99.56%&quot; (they presumably actually meant obscuration; this is from a vantage point that is probably about as close to the path of totality as it's physically possible to get in Toronto while still being on land).</p>
<p>This was enough, per CBC News coverage, to have <a href="https://youtu.be/IUpydw84qYA?&amp;t=2078" rel="nofollow noreferrer">noticeable</a> effect on animal behaviour and cause a large drop in temperature - presumably substantively the same drop as observed within totality (since, although the human ocular response to light is highly non-linear, the same can't really be said about the Earth's temperature response to incident infrared radiation). A temperature drop is detectable with even a fairly small amount of obscuration, although it isn't very impressive. But from my own experience within totality, it was not noticeably colder at totality than several minutes before. (It did seem to warm up more quickly afterward, but that may have been psychological.)</p>
<p>I was also able to find some <a href="https://www.youtube.com/watch?v=YqVZJEgBJ94&amp;t=4898" rel="nofollow noreferrer">independent local footage</a> (timestamped at or near the moment of maximum eclipse). It's dark enough to impress viewers and commentators, and quite noticeable on film, but still bright enough to see clearly in an area with tons of light pollution. It looks like moderately deep twilight rather than late night. I know there is some other footage I saw by the CBC taken from a rooftop of their building, which looked somewhat darker than this (away from street-level lights); but I can't seem to find it now.</p>
<p>Here's <a href="https://youtu.be/IUpydw84qYA?t=2378" rel="nofollow noreferrer">another timestamp</a> from the same CBC News coverage, allowing us to see the contrast between the darkness of totality (as seen in Kingston) and the near-totality in Toronto.</p>

CC BY-SA 4.0
2024-04-10T23:20:24.170Z
[This webpage](https://sciences.utsa.edu/physics-astronomy/eclipse.html) is completely right. In London, Ontario, the eclipse was at a maximum of 99.8%. But there was no corona, no evening effect, no temperature drop noticeable. But the light was darker enough to cause the road lights to turn on. So it needs 100% eclipse and the longer lasting time, the better effects.
E Zhang
CC BY-SA 4.0
2024-04-10T21:48:57.287Z
2024-04-10T21:48:57.287Z
Karl Knechtel
<p>In the incoming April total eclipse in North America, if a city's sun is said to be 99.5% blocked, What darkness can it reach compared to the period of dawn or dusk or evening?</p>
<p>I ask this question because I live in a city where the sun is said to be 99.5% blocked during the eclipse. So if the darkness is similar to a predawn level (dark enough), there is no need to travel to a place (50-100 kilometers away) where the sun is 100% blocked, especially on a cloudy day.</p>

CC BY-SA 4.0
2024-03-23T15:20:10.153Z
The light from a 99.5% obscured sun high in a clear sky is nothing like the diffuse glow of twilight from the western horizon. If you took a photo using your phone or a point-and-shoot camera during the 99.5%  eclipse, you would later have a hard time convincing anybody that you didn't simply take it in broad daylight on an ordinary day. It _looks_ like broad daylight, except... well... without as much light. I expect you'll find out in a couple of weeks what I'm talking about (if the weather cooperates.)
Solomon Slow
CC BY-SA 4.0
2024-03-23T15:30:48.890Z
Yes, you are right. I already found a webpage which answers it and confirms yours. So it is necessary to go to places of total eclipse to witness all the effects. 99.9% is not enough.
E Zhang
CC BY-SA 4.0
2024-03-25T02:41:39.987Z
Having experienced a total solar eclipse, I can tell you it is nothing like normal darkness. It's spooky. Animals do weird things. [Shadows are strange](https://www.abc4.com/news/national/what-are-the-beautiful-crescent-shaped-shadows-that-occur-during-an-eclipse/).
Schwern
CC BY-SA 4.0
2024-03-22T08:24:42.453Z
A closely related question on our sister site: [How different is a 99.5% eclipse from a total eclipse?](https://physics.stackexchange.com/q/806950/123208)
PM 2Ring
CC BY-SA 4.0
2024-03-22T16:02:27.963Z
The sun will be too bright to look at even at 99.5%.  Anywhere more than a mile outside of totality the corona won't be visible.  You'll want to get inside the path of totality if at all possible.
Greg Miller
<solar-eclipse>
The darkness that is equivalent to the block of 99.5% of the sun
E Zhang
# The darkness that is equivalent to the block of 99.5% of the sun

(Asked by: username_0 on 2024-03-22)

In the incoming April total eclipse in North America, if a city's sun is said to be 99.5% blocked, What darkness can it reach compared to the period of dawn or dusk or evening?

I ask this question because I live in a city where the sun is said to be 99.5% blocked during the eclipse. So if the darkness is similar to a predawn level (dark enough), there is no need to travel to a place (50-100 kilometers away) where the sun is 100% blocked, especially on a cloudy day.

**Tags:** solar-eclipse
> **Comments:**
> **username_3**: A closely related question on our sister site: [How different is a 99.5% eclipse from a total eclipse?](https://physics.stackexchange.com/q/806950/123208)  
> **username_4**: The sun will be too bright to look at even at 99.5%.  Anywhere more than a mile outside of totality the corona won't be visible.  You'll want to get inside the path of totality if at all possible.  
> **username_1**: The light from a 99.5% obscured sun high in a clear sky is nothing like the diffuse glow of twilight from the western horizon. If you took a photo using your phone or a point-and-shoot camera during the 99.5%  eclipse, you would later have a hard time convincing anybody that you didn't simply take it in broad daylight on an ordinary day. It _looks_ like broad daylight, except... well... without as much light. I expect you'll find out in a couple of weeks what I'm talking about (if the weather cooperates.)  
> **username_0**: Yes, you are right. I already found a webpage which answers it and confirms yours. So it is necessary to go to places of total eclipse to witness all the effects. 99.9% is not enough.  
> **username_2**: Having experienced a total solar eclipse, I can tell you it is nothing like normal darkness. It's spooky. Animals do weird things. [Shadows are strange](https://www.abc4.com/news/national/what-are-the-beautiful-crescent-shaped-shadows-that-occur-during-an-eclipse/).  

---

## 7 answers

### Answer by username_0 on 2024-03-22. Score: 3 | Accepted answer

[This webpage](https://sciences.utsa.edu/physics-astronomy/eclipse.html) answers my question completely. Even a 99.9% block of the sun belongs to a partial eclipse, you can not experience any of the following:

* temperature & wind changes
* dramatic brightness changes
* sunset colors around horizon
* bright stars and planets
* corona, diamond ring effects, and others

So a 99.9% eclipse will not be enough at all. You need a 100% eclipse to enjoy those experiences.

> **Comments:**
> **username_6**: This may be the answer you wanted, but it is not an actual answer to your *stated question* of what "night hour" or "evening/morning hour" has equivalent darkness. My [answer](https://astronomy.stackexchange.com/a/57234/32118) does address that.  
> **username_0**: No, it answers exactly what I want to know. It says that no dramatic brightness changes, no sunset colors around the horizon, and no bright stars and planets under the 99.9% eclipse, which means people can not really experience the change of daylight and night even under the 99.9% eclipse.  
> **username_5**: @EZhang *Welcome to Stack Exchange!* It's always OK to answer your own question, and to accept the answer if it's the best one. However we really avoid *changing the question* once answers start to be posted. Try to avoid doing that in the future, *thanks!*  
> **username_5**: @EZhang I also find it frustrating when answers suggest the question is not the right question to ask. It happens occasionally, I just ignore it. Sometimes answer posts are written more for the benefit of future readers, or general interest, than they are the question author's specific interest. I call this [uhoh's lemma #3](https://meta.stackexchange.com/q/377004/303080) Stack Exchange is BOTH a floor wax, AND a desert topping :-)  

---

### Answer by username_6 on 2024-03-22. Score: 18

I agree with James K's observation that the main point of a total eclipse is not the darkness but the visibility of the corona.

However, to answer your original question, blocking 99.5% of the Sun\* would reduce the daytime [illuminance](https://en.wikipedia.org/wiki/Lux#Illuminance) by a factor of 200, roughly from 20,000 lux (full [daylight](https://en.wikipedia.org/wiki/Daylight)) to 100 lux. Even so, this would not feel very dark, because our eyes have a very wide dynamic range.

At dawn or dusk (in the absence of an eclipse), natural illuminance of 100 lux occurs during [civil twilight](https://glossary.ametsoc.org/wiki/Civil_twilight) shortly before sunrise or shortly after sunset. You can still see well. For additional context, this is [comparable](https://en.wikipedia.org/wiki/Lux#Illuminance) to a day with very heavy overcast clouds, or to the indoor lighting in an office building.

So the change in general brightness during a 99.5% eclipse is noticeable, but not dramatic. Even if the eclipse is covered by clouds, there would be a much bigger perceived change in brightness where the eclipse is total. And if the eclipse can be viewed clearly, then of course there is no comparison.

\* A technicality: The most commonly quoted measure of a partial eclipse, the "magnitude", is the maximum fraction of the Sun's apparent *diameter* (not *area*) that is covered by the Moon. So for a precise answer, you would need to ensure which number you read. I will assume here that 99.5% is the fraction of area, known as the "obscuration". The issue does not affect the qualitative conclusions.


---

### Answer by username_7 on 2024-03-22. Score: 18

This misses the point.

During totality the sun's corona becomes visible. If any part of the photosphere is exposed, then the corona isn't visible.

The experience of a total eclipse is not just "darkness" (you get about 12 hours of that every day!) It is the ring of the solar corona.

To answer your question, 99.5% of the sun is obscured a few seconds before sunset. But this isn't a fair comparison since at sunset the sun is obscured by the Earth which is inside the atmosphere, and during an eclipse the sun is obscured by the moon, which is beyond the atmosphere.

My granddad used to say "a miss is as good as a mile" If the sun is not covered by the moon, it is a partial eclipse and those are pretty common. You will only experience totality if the sun is covered by the moon. 99.5 % is not totality and is a completely different thing.

> **Comments:**
> **username_0**: This does not answer my question. I do not care whether I can see the solar corona with the naked eye or not because I have an eclipse glass. Nor do I care if it is obscured by the Earth's atmosphere or others. I just want to know if the 99.5% blocked sun would like a night, or closer to nightlight than daylight. For me, the most important thing is to experience a sudden change to the night environment from daylight.  
> **username_7**: I've edited. If all you care about is the change from light to dark, I suggest you go out at between 6 and 7 pm then.  You will experience a change from day to night.  Or go out between 5  and 6 am.  You will experience a change from night to day.  These are not special.  If you are not in totality you are not experiencing a total solar eclipse. And, frankly, who cares about a partial eclipse?  Those happen every couple of years.  Totality is special.  99.5% is rubbish by comparison.  
> **username_0**: The change of light at sunset/sunrise takes some time. In a total eclipse the change is much quicker I think. Put in another perspective, can stars be seen under the 99.5% block of the sun? I know they can be seen under 100% block of the sun. Is 99.5% still belonged to partial eclipse?  
> **username_7**: Feel free to self answer.  
> **username_4**: @EZhang you state in your question that "there is no need travel to a place where the sun is 100% blocked".  James' answer explains why that's not the case.  If all you want to see is darkness, just wait until night time.  
> **username_6**: @EZhang "can stars be seen under the 99.5% block of the sun?" -- no, see my answer -- bright stars become just visible at the dark end of [civil twilight](https://glossary.ametsoc.org/wiki/Civil_twilight), with illuminance of around 3 lux, which would require 99.99% blocking.  
> **username_6**: @JamesK You acknowledge that considering the fraction of the Sun visible at sunset "isn't a fair comparison". Of course, this is because atmospheric scattering provides significant illuminance even when the Sun is entirely below the horizon. To this end, my [answer](https://astronomy.stackexchange.com/a/57234/32118) uses data on twilight brightness to answer OP's specific question more accurately.  
> **username_7**: @nanoman agree, upvoted.  
> **username_0**: @Greg Miller, James' answer is not enough. As I explained, the change of twilight is slow. I want to experience a quick turn from daylight to evening. I found a webpage that perfectly answers my question. So I answered it in a post.  
> **username_8**: @EZhang The covering of sun by the horizon at sunset is caused by the earth's rotation (once per day). The covering of the sun by the moon during a solar eclipse is caused by the moon's revolution (once per month). So the transition from light to dark is about 28 times *slower* during a solar eclipse than during a sunset.  
> **username_6**: @GregMartin That would be true if sunset darkness were purely a function of geometric occlusion of the Sun -- e.g., if the Earth had no atmosphere. In reality, there is of course a long, gradually dimming twilight after sunset. Though the Sun appears to set quickly (crossing over the horizon in a few minutes), this does not immediately produce a big change in overall illuminance because so much of the setting Sun's light is scattered by the atmosphere. The sky as a whole is almost as bright just after sunset as just before. Compared to this, the final darkening of a total eclipse is rapid.  

---

### Answer by username_9 on 2024-03-22. Score: 10

There's no equivalent. At 99.5% coverage, the overall light level is comparable to that of twilight a few minutes after sunset. However, the majority of the light is still coming from a point source, so you get phenomena such as sharp shadows that aren't present after sunset. The overall result is an impression of "wrongness" to the light, but it's nothing like the experience of totality.

During the 2017 eclipse, I recorded a video of the final 30 seconds before totality in an attempt to catch the Moon's shadow sweeping across the ground. It mostly didn't work, but I did catch a phenomenon nobody had mentioned before: the crowd cheering the moment totality started. Below is a frame from 25 seconds before the cheering, showing how a camera sees 99.5% coverage.

[![enter image description here](https://i.sstatic.net/eIuXg.jpg)](https://i.sstatic.net/eIuXg.jpg)


---

### Answer by username_10 on 2024-03-22. Score: 4

My experience with the last total eclipse was that it got noticeably dimmer and instantly cooler. It was not like night at all. I would say the level of light was probably closer to dawn, or like when a heavy cloud goes over the sun.


---

### Answer by username_5 on 2024-03-24. Score: 2

### Snakes!

In addition to [@Mark's answer](https://astronomy.stackexchange.com/a/57235/7982) that everything looks "wrong" with a near point-like dim source (basically this is what daylight looks like at 15 AU, (between Saturn and Uranus)) there are other effects you can think about. I am not sure 99.5% coverage is enough, but when the Sun is covered except for a very, very thin sliver, atmospheric effects on Earth called "shadow snakes" or what Wikipedia calls [shadow bands](https://en.wikipedia.org/wiki/Shadow_bands) become visible.

Slightly related: [Would an extremely bright star produce same kind of shadow band effect as seen in solar eclipses just before totality?](https://astronomy.stackexchange.com/q/27226/7982)


---

### Answer by username_11 on 2024-04-10. Score: 1

The eclipse as seen in Toronto, Ontario, Canada [reached](https://www.timeanddate.com/eclipse/in/canada/toronto?iso=20240408) a maximum magnitude of 0.998, [reported](https://trca.ca/solar-eclipse/) on a Toronto and Region Conservation Authority website as "a magnitude of 99.56%" (they presumably actually meant obscuration; this is from a vantage point that is probably about as close to the path of totality as it's physically possible to get in Toronto while still being on land).

This was enough, per CBC News coverage, to have [noticeable](https://youtu.be/IUpydw84qYA?&t=2078) effect on animal behaviour and cause a large drop in temperature - presumably substantively the same drop as observed within totality (since, although the human ocular response to light is highly non-linear, the same can't really be said about the Earth's temperature response to incident infrared radiation). A temperature drop is detectable with even a fairly small amount of obscuration, although it isn't very impressive. But from my own experience within totality, it was not noticeably colder at totality than several minutes before. (It did seem to warm up more quickly afterward, but that may have been psychological.)

I was also able to find some [independent local footage](https://www.youtube.com/watch?v=YqVZJEgBJ94&t=4898) (timestamped at or near the moment of maximum eclipse). It's dark enough to impress viewers and commentators, and quite noticeable on film, but still bright enough to see clearly in an area with tons of light pollution. It looks like moderately deep twilight rather than late night. I know there is some other footage I saw by the CBC taken from a rooftop of their building, which looked somewhat darker than this (away from street-level lights); but I can't seem to find it now.

Here's [another timestamp](https://youtu.be/IUpydw84qYA?t=2378) from the same CBC News coverage, allowing us to see the contrast between the darkness of totality (as seen in Kingston) and the near-totality in Toronto.

> **Comments:**
> **username_0**: [This webpage](https://sciences.utsa.edu/physics-astronomy/eclipse.html) is completely right. In London, Ontario, the eclipse was at a maximum of 99.8%. But there was no corona, no evening effect, no temperature drop noticeable. But the light was darker enough to cause the road lights to turn on. So it needs 100% eclipse and the longer lasting time, the better effects.  

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