Mark your calendars for March 16 through 28. Don't ask why, yet. Now, read on….

Composite image showing centers of urban light emission
Credit: NASAWant a chance to do some "citizen" science, contribute to an international investigation, and have some fun to boot? An opportunity is coming up in March: Globe At Night. All you need is your eyes….

The problem is summed up in two words: light pollution. A good deal of light produced by human civilization–streetlights, porch lights, shopping malls, security lighting, night time work lights, store fronts, parking lot lights, billboards, neon signs, the list is lengthy–shines or reflects upward into the atmosphere, there scattering off of suspended particles, like dust grains, water droplets, ice crystals and the like.

The scattered light shines back down from the sky, and we see it as a dull nocturnal glow, sometime faint, and sometimes quite pronounced. The amount of scattering particles in the air has an effect on the brightness of the night sky, but the root of the matter is the amount of light sources whose light escapes upward. The closer you are to the heart of an urban area, the more light pollution you will be subjected to.

So what? What's so harmful about that sky glow? Sometimes it can even look kind of pretty….

Well, the fact is, if you've never seen a clear night sky far from sources of major light pollution, you may not appreciate what you're missing: the sight of a clear and dark night sky in which you can literally see thousands of stars. And if you have seen a pristinely dark night sky before, think about the fact that, in 2008, half the population of the Earth was living in cities, many of whom may never have been out of their urban worlds, and for whom the night sky is naturally a dull version of day with a handful of washed out stars above.

There are also effects of light pollution on wildlife that include disturbance of day/night sleep cycles, less cover of darkness from predators, and even effects on plant life.

Globe At Night is a program that's been going on for a few years now whose aim is to measure and monitor the varying levels of light pollution around the world by using individual people as the instruments of measurement.

And it's pretty simple to participate in. The idea is that the brighter the light pollution is in any given location, the few stars you can see. The faintest stars quickly become drowned out in the sky glow, leaving only the brighter ones for your eyes to pick out. All you have to do is go outside on one or more nights in the last half of March, find the constellation Orion (which is pretty easy to find, even in a city), and count the number of stars you see there. Then, report your count through the Globe At Night website, where you'll also be able to see the observations of everyone else around the world, as well as find full instructions for participating.

Now, calendars marked? Know where Orion is? Have a sweater handy? You're all set….

There's nothing like a trip away from the city lights to remind you just how bad light pollution can be here in the Bay Area.

The Milky Way in the skies of Death Valley's
Devil's Racetrack. Credit: Dan Duriscoe, U.S. National
Park ServiceI just got back from my semi-yearly pilgrimage to my favorite spot on Earth: Death Valley National Park. My main reasons for returning to this place again and again have mostly to do with hiking in the stunning natural beauty of the place, reconnecting with good times in my childhood, and reflecting spiritually on life, the Universe, and everything.

But, I can't go to a place like that and not feel more connected with outer space. Not only is the night sky a celestial spectacle–but it's darned cold there too, this time of year! Cold, like space. Each turn of the Earth through its own shadow is like a quick dip in the icy pool of space….

After twilight had faded, after the campfire had burned to embers–and as the frigid cold of the desert winter night started seeping through my layers of clothing–I lay down on the picnic bench and raised my binoculars to my eyes…

…and that's all I had to do. Arcing overhead was the section of the Milky Way around the constellations Cassiopeia, Perseus, Andromeda, Pegasus–a section of the sky rich in a variety of "deep sky" objects (objects typically only visible through binoculars or telescopes).

There was the Double Cluster in Perseus–a pair of "open" clusters of stars.

Open clusters are stars bound together gravitationally, still clinging to each other after their "group infancy" in the gaseous cloud that gave birth to them. Stars in these clusters are young–and because of their youth, open clusters often contain a number of large, bright, blue stars that shine brilliantly–but which have short life spans as stars go, being more prolific hydrogen-burners (gas guzzlers). (In a word, you can't find an old blue giant star.)

You can't avoid seeing open clusters in this region; the place is positively littered with them….

This is also where the famous Andromeda Galaxy can be found, in the constellation Andromeda (where else?). What's special about the Andromeda Galaxy? For one, it's the closest large galaxy to our own, as well as the most distant object in the Universe that can be seen with the unaided human eye (without telescopic help). Looking at the Andromeda is like looking through a peephole into the realm beyond our Milky Way…

I could go on and on yakking about what I got to see in the clear, dark Death Valley skies last week, so I'll have to stop myself now. Suffice to say that with a dark sky, a pair of binoculars, and a segment of the Milky Way in view, encountering the celestial wonders of the Universe in a very personal way is like shooting ducks in a barrel.

But don't let the light polluted skies of the Bay Area stop you from trying it from your own backyard; there's a lot to behold despite the city lights…

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.