Is it possible I'm a 6.5 on the Bortle scale?

[MarkVIIIMarc]

Wow even though I am in a fairly non developed area outside a neighborhood on on of the smaller acra plus lots (land is cheap here), I have noticed quite a bit of light pollution! 

Using the Bortle scale on Wikipedia I'd rate condition as a 6.5.

My U.S. zip code is 63138 (told you, cheap land here). And to me that seems consistent with the various light pollution maps I see online. Does that seem correct to you all?

I don't see the Milky way

Within 35 degrees of the horizon especially to the south there is a glow

The undersides of clouds glow at night, light not yellow.

I see about magnitude 3 stars. I can see the Big Dipper but parts of Leo were not visible last night with no moon.

[happy-kat]

Hi

What are you asking is possible?

[acey]

I hold little faith in the Bortle scale and don't consider it a useful way of assessing sky quality. You say you can see stars to mag 3, which is enough to establish that your sky is heavily light polluted. You say you can't see the Milky Way, which is what you would expect if you can only see stars to mag 3. You say you can see significant light domes, and clouds are illuminated, which is consistent with heavy light pollution. For what it's worth, I'd put your Bortle figure at 7 or 8. But I don't think it's worth much. Far more relevant is your stellar magnitude limit, which you put at 3. If you can see all the major stars of Ursa Minor then it's better than 3, but your sky is evidently still heavily light polluted. A "dark" sky is one where you can see the Milky Way (at appropriate times). Anything else is significantly light polluted. It's that simple.

Nor are light pollution maps to be trusted. In most cases they use population data and guess light pollution as a function of that. The only way to get an accurate assessment of light pollution at a particular site is to go there, look, and measure. If the maps you see online rate your sky as 6.5 then clearly the maps are wrong (assuming you're a normally sighted person). For Bortle 6.5 the Milky Way is "still impressive but lacks detail", and you can't see it at all.

[MarkVIIIMarc]

2 hours ago, happy-kat said:

Hi

What are you asking is possible?

In a way I am asking myself because I always considered my yard to be darker than that.

With Stellarium you can input your magnitude and pollution levels to get a realistic vies of your sky. That helps me figure out what I am looking at and helps me find things. 

Is the light pollution scale a useful for conversation when seeking advice or what is more handy?

[acey]

1 hour ago, MarkVIIIMarc said:

Is the light pollution scale a useful for conversation when seeking advice or what is more handy?

Limiting magnitude for stars is the best indicator, in the absence of Sky Quality Meter or similar device. The Bortle Scale has been shown to be unrealistic and unreliable in a number of ways.

[jetstream]

I totally agree about the NELM and the Milky Way as being great indicators and also about the usefulness of the SQM-L. The SQM is a fast way to find pockets of dark sky or "map" the light dome edges around/in cities and towns. Some light pollution maps are not that accurate, IMHO, but I do like the zoomable Blue Marble to start looking for dark pockets.

On dark and calm nights the Milky Way will reflect its glow off the lake in front of my house..... and yet my "Bortle" rating is not truly dark according to a few maps. These days one look at the Milky Way tells me how good the transparency is.

The bright, sharply defined Milky Way is a sight to behold with dark rifts cutting and slicing though it.

[DaveS]

Your description sounds similar to mine, which I would rate no better than Bortle 8. I can see to mag 4 plus a bit depending on the clarity of the sky.

[acey]

4 hours ago, MarkVIIIMarc said:

In a way I am asking myself because I always considered my yard to be darker than that.

We all think we have a dark yard until we take up astronomy and wonder why we can't see DSOs very well. Our eyes adapt to our surroundings, and in a light-polluted environment a clear sky will look black, simply because we're dazzled by ground light. This is why we use naked-eye limiting magnitude (or SQM readings) to assess sky darkness, rather than the subjective impression of whether the sky happens to look dark. By analogy, think of what you would count as a "quiet" place. A place can seem quiet even when there's a lot of background noise that we unconsciously filter out. A possible test of quietness is being able to hear a pin drop. Limiting magnitude is an analogous test, with a scale we could think of as pin, pencil, brick...

The Bortle Scale is more elaborate in its criteria, and it was partly motivated by two factors. One was the correct observation that everyone's eyes are different: one person might see to sixth magnitude while another sees only to fifth. Second was the incorrect assumption that visibility of extended objects (e.g. the Milky Way or Andromeda Galaxy) is independent of limiting magnitude. In fact, limiting magnitude is a sufficient predictor of the visibility of extended objects, which is why limiting magnitude is sufficient. And variation of people's acuity is as much an issue in the Bortle Scale as in limiting magnitude. The Bortle Scale also attempts to include environmental factors such as the visibility of clouds or surroundings, but again, these depend a lot on specific conditions, and are not good for general use.

[MarkVIIIMarc]

All interesting. I suspect without looking up, my yard LOOKS pretty dark at ground level. I have two real neighbors, one to each side 125'(40 meters) away and no one directly across or in back of me for a kilometer or so. We have good bonfire parties lol.

HOWEVER, I am only 13ish miles due north of the Gateway Arch....maybe 20 kilometers and while to my immediate north and east there is suburbia then open land, you do have bright Alton and Granite city 6 miles, 10 kilomters away.

Which sure enough causes some light pollution! Amazing how far that travels. I remember aporoaching Vegas one night from the south how bright it was at a distance. I should have applied it locally to StLouis.