Test your light pollution
The new moon this week is a great opportunity for dark skies
If you’re new to this newsletter, welcome! I’m Abby. I’m a freelance science journalist, stargazing columnist and author of The Art of Urban Astronomy. I live in England, where we have just entered a THIRD lockdown. I started this newsletter to help people through the dark nights, with ideas of what to look for in the skies each week. If you live in the southern hemisphere don’t worry, I always try to make sure it applies to stargazers around the world.
Do you want to come on holiday with me? I am very excited to share that in November I’ll be joining a New Scientist Tours trip to Chile. We will be visiting world leading observatories including ALMA and Paranal, seeing a lunar eclipse and stargazing at several sites near San Pedro, Santiago and Vicuña. If you’re interested, you can read more and sign up for information when it goes on sale, here.
This week is a new moon (on Wednesday, 13th January) which means it’s a good time for anything that might require darker skies. One activity I really enjoy is testing out the light pollution wherever I am stargazing from, by finding the Great Square of Pegasus. If you haven’t done this before, a clear sky this week might be a great opportunity. Pegasus can be seen between 90 and -60 latitudes so that covers pretty much most of the planet!
The square of Pegasus is an asterism made by three stars from the constellation Pegasus, and one from the constellation Andromeda. To find it, it’s best to start with Cassiopeia, the W or M shaped constellation usually found near the north star.
Looking at Cassiopeia, you should be able to tell which V in the constellation is deeper than the other. If it looks like a W, this will be on the right.
Follow the arrow this deep V creates and you’ll see a fuzzy patch about the size of the full moon. This is the Andromeda Galaxy or M31. Slightly further, there should be a line of stars slightly curling underneath around this fuzzy patch. This line leads to a large square with a bright star at each corner - the Great Square of Pegasus.
Once your eyes have adjusted, counting the stars inside this square gives a good indication of what the light pollution is like in your area.
Best of luck and, as always, please let me know how many you find! If there’s anything in particular you want me to cover in this newsletter, do let me know.
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