With so many of us home or not venturing far from home in these COVID-19 times, it’s a great time to do some local backyard astronomy. And you can contribute to valuable citizen science efforts by submitting your observations to GLOBE at Night. This year’s campaign extends through the entire calendar year, so take advantage of any clear skies, do some observing, and be included in this study of light pollution worldwide!
As of July 2020, citizen scientists from around the world have contributed 20,442 night sky observations to help quantify light pollution around the world. Participating is simple: go outside about one hour after sunset and locate the constellation(s) identified for that month.
Once you’ve found the constellation in the sky, compare your observation with a brightness magnitude chart, and report your finding along with your latitude and longitude on the website. You can look at the GLOBE at Night results to see how the light pollution of your skies compares with that in other locations around the world.
This year’s observing period continues through December, so visit the website to learn more, get out there and marvel at the stars, and submit your observation to be counted and contribute to learning more about light pollution, both locally and globally.
A blast from the past! Oil spills and unit conversations, a middle school Practical Uses of Math and Science (PUMAS) example published in 1999.
The short story: On February 4, 1999, the 639-foot freighter New Carissa became grounded near Coos Bay on the Oregon coast. Aboard the ship were 400,000 gallons of bunker fuel, threatening to leak from the fractured hull and damage the state’s fragile beach habitats. With an approaching storm increasing the chances of a disastrous spill, authorities decided to set the ship afire, a choice not without controversy and risks of its own. What would be the potential scale of the disaster if that much oil did spill? 400,000 gallons is equivalent to 400,000 milk jugs –- a lot of milk. But how much space does 400,000 gallons really take up? Some simple arithmetic can help put the quantity in perspective.
A seiche is an oscillation associated with a standing wave that occurs in an enclosed or partially enclosed body of water, resulting from seismic activity or meteorological effects.
Seiches have been observed on lakes, reservoirs, ponds, rivers, and even swimming pools. You can create your own seiche in your bathtub, just by rocking back and forth. At the right frequency, you can set up an oscillation–essentially a small-scale seiche–that allows the waves to grow until they overflow the bath.
A similar “sloshing”–in this case a seismic seiche–was observed on Saturday, February 27, on Lake Pontchartrain in Louisiana, caused by an earthquake 4,700 miles away off the coast of Maule, Chile. Lake Pontchartrain sits on the Mississippi Delta, which contains a deep layer of surface sediments. Seismic waves can resonate through this sediment more easily than through more firm surface types, making the Gulf region particularly sensitive to earthquake-induced seiches. The seiche affecting Lake Pontchartrain occurred 11 minutes after the 8.8 magnitude Chilean earthquake and resulted in water levels about 6 inches higher than the predicted tides.
Want the video version? Derek Kevra at WWLTV has a great explanation of the quake and resulting seiche here. And if you want to learn more about seiches in history, check out this page from the USGS Earthquake Hazards program.
A new month in a new year and it’s gone by far too quickly. I thought I’d close out the lengthening days of January by sharing some interesting sources of information. The pick for today is the NOAA Sunrise/Sunset Calculator, developed by some talented former colleagues. It is a resource used by people in all walks of life—from scientists and sky watchers to film makers and event planners—and a great way to explore what’s going on in terms of the number of hours of daylight received in a day.
According to the calculator, at 40 degrees latitude in the approximate middle of the mountain time zone, the apparent sunrise on January 31 is 7:09 a.m. and apparent sunset is 5:19 p.m. What’s “apparent” sunrise, you ask? Let’s use this graphic from the solar calculator Help Guide (really guys, great work putting this resource together!) to illustrate:
Earth’s atmosphere refracts (or bends) incoming light from the Sun. Because of that refraction, we see the sun “rise” shortly before it actually crosses the horizon. Likewise, we see the setting sun for a short time after the sun has actually “sunk” below the horizon at the end of a day. (If this part sounds like desperation from a person eager for any at all additional daylight, well, consider that mid-latitude winters sometimes just seem…long.) Apparent sunrise and sunset times are different than actual sunrise and sunset times, adding just that little bit of additional time to the number of hours of daylight in a day.
The nice thing about the end of January sunrise and sunset times is how they differ from the dark, dark days of December. Did we talk about the solstice on December 21? On that day, the apparent sunrise was at 7:18 a.m. but the sun was gone a full 40 minutes earlier, at 4:39 p.m. For those of us desperate enough to grab those few minutes based on apparent sunrise and sunset, 40 minutes seems quite a cause for celebration, or at least acknowledgment. Go ahead, play with sunrise and sunset times for your location, and check out what happens at the summer solstice too.