Mental Floss

The Quick 10: The Bortle Dark-Sky Scale

Stacy Conradt
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Did our U.S. readers enjoy some fireworks last weekend? We didn't - they got rained out. Thanks to light pollution, the fireworks in some parts of the world will appear more brilliantly than others. The Bortle Dark-Sky Scale tells us where you'll find yourself observing the night sky in inky blackness or if you'll be squinting to make out even the moon. Check out the different levels and let us know where you rank!

2. Gray - typical truly dark site. You'll still see M33 pretty easily, but it's not as clear as it would be if you were hanging out with your telescope in remote areas of Australia.

3. Blue - rural sky. This is where you get into some light pollution. Not much, but enough that you can see your telescope pretty easily from 30 feet away.

4. Green - rural/suburban transition. It might be dark overhead, but off in the distance you're starting to get some fairly major light pollution over populated areas. Good luck seeing M33 unless you're at a higher altitude.

8. Red - suburban/urban transition. As you leave suburbia and head into the Big City, your view becomes even more obstructed. The sky doesn't really even look dark anymore - it's more of a grayish tone. Even the bright Milky Way is most likely invisible from this point of view.

9. White - city sky. Want to read a newspaper? You won't need a flashlight to scan the headlines in this light. That's great if you're looking to catch up on the day's events; not so great for star searching.

10. White - inner city sky. Yeah... sadly, you're not going to see much from this vantage point, even some of the most common constellations. But hey, you can still see the moon. That's a plus.

So where do you live? Can you see constellations pretty easily? Galaxies? Planets? According to Google Maps, my house falls under the yellow category. Need a little help figuring out what you can see from your house? This site is pretty handy.

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