Backyard Light Pollution

Too Many Lights!

When we first moved to our new home in Williamsburg I was thrilled with prospects for backyard astronomical observing. No large trees blocked the view. Neighboring lots were initially empty. There was an unobstructed view of the southwest horizon. It wasn't long, however, before vacant lots were occupied by two-story houses blocking nice horizon views. Then neighbors moved in. Now my backyard is surrounded by houses, each equipped with rear spotlights which make nighttime observing nearly impossible.

Imagine standing on my backyard observing pad with telescope ready to go. Facing southwest you see this view.

Turning slightly right to look more directly south reveals another glaring light seen below.

If I'm unlucky and both neighbors light the night at the same time, I see this.

Now turn about 90 degrees farther right to face west. Here are the most troublesome discouraging lights of all.

The upper beacon in the previous image is an extremely bright interior light, not an outside spotlight. It blasts out through a semicircular second story window lacking blinds or curtains. It shines directly in my face whenever I step into the yard to check the sky, and it rarely turns off. This nemesis light often remains lit well past midnight, sometimes all night long! Underneath the awful second story light is another ever shining first story interior light glaring through open blinds. I can imagine humbly asking other neighbors to please turn off their outdoor spotlights, but how can I ask someone to turn off lights inside their home? Maybe a bold character could do this, but I'm not that person!

Now turn right another 90 degrees towards southwest to find the remaining awful lights.

To be honest, all five nightmare lights seldom shine simultaneously. In fact, the two northern lights only come on during infrequent nighttime barbecues. One of the southern lights usually shines temporarily to let a dog out. The other southern light, however, is frequently on continuously in the summer. Still, it actually takes only one active light to ruin observing.

 

The worst lights are the interior house lights in the east/southeast. They glare out all night almost every night year round. By unfortunate alignment they shine directly on my observing pad. If I move to the edges of my yard, window frames block direct sight lines to these awful lights. Unfortunately, telescopes can't be set up at these places.

 

What's the probability of finding all five lights simultaneously off? Very low! Sometimes I dream about a power outage. Power outages from storms aren't often accompanied by clear skies, however. 

 

From time to time, fool that I am, I set up a telescope for observing on some clear moonless night. It doesn't take long for frustration to set in as, seemingly at random, spotlights turn on and off destroying whatever modest dark adaptation I manage to accumulate. It's very discouraging. Then I'm reminded why I chose to specialize in daytime solar imaging rather than nighttime deep sky imaging.

 

I've fantasized about ways to block the lights, but possibilities all seem impractical or too expensive. My favorite fantasy is motorized black fence panels that elevate all around my yard blocking each and every light! Of course, I could travel to a darker location, but this is increasingly unattractive the older I get. When I was younger I would spend all night driving around the countryside setting up a telescope at various places. I could do this for hours past midnight, then get up the next morning for work. At this point, however, I can't summon the energy required to pack up equipment, haul it to a dark site, set it up, face possible deteriorating sky conditions, break down equipment, store it back in a vehicle, haul it back home and unpack it all. The convenience of backyard observing is too great in comparison. Traveling is just impractical. So, I'm stuck with backyard light pollution.

Solar Energy Production - Part 2

Seasonal Changes

My solar panels have been operating for six months, long enough to go from the June summer solstice to the December winter solstice. The panels have now experienced a full range of seasonal solar altitude and azimuth changes from maximum to minimum. As expected, energy production steadily diminished from June thru December as daylight grew shorter and solar altitude decreased.

The panels became operational on June 19th, one day before the summer solstice. Clouds, of course, affect power output, so I found the clearest possible cloud-free days to track seasonal changes. The first nearly cloud-free day after June 19th was June 26th when the panels produced their biggest amount so far, 20.63 kwhrs as shown in the following image. Some thin clouds appeared in late afternoon on June 26th, so I'm sure the absolute summer solstice maximum is slightly greater than 20.63 kwhrs.

The autumnal equinox happened on the morning of September 22nd. This day was, conveniently, completely cloud-free from sunrise to sunset! Energy production on September 22nd was 17.25 kwhrs as shown below.

The winter solstice happened on the morning of December 21st. Unfortunately, December 21st was completely overcast. December 26th, five days later, was the completely clear day closest to the winter solstice. Energy production on December 26th was 11.81 kwhrs as shown in the next image.

When no clouds interfere, energy production curves are nearly symmetric about their peaks except for small diminishing tails on the right side just before sunset. You can see the curves narrow as daylight hours decrease. Energy production is greatest while the Sun is near meridian transit around noon. At the summer solstice there is a broad flat maximum peak value at 0.60 kwhrs. At the autumnal equinox peak production is still at 0.60 kwhrs, but the flat peak has narrowed. At the winter solstice there is no flat peak, and the peak maximum value has dropped to only 0.50 kwhrs.

I've given examples of the best possible days for solar energy production. What about the worst days? The worst day so far happened on November 12th, a dark, completely overcast day with rain. In spite of heavy black clouds, dim light generated 0.56 kwhrs for the day as shown below.

I can imagine even lower energy production on a cold, dim, snowy day near the winter solstice when snow covers the panels from dawn to dusk.

Based on solar panel performance during the past six months I should have installed fourteen panels instead of ten. Fourteen panels would generate close to my usual yearly energy use without exceeding actual energy use. I'll be investigating what's involved in adding four more panels soon.