What Happens Under The Stars While We Sleep

Looking northwest at dusk earlier this week. The muted pastel light is caused by sunlight reflecting off air and dust in the atmosphere. I always make a point to look for blue-colored wisps of noctilucent clouds along the horizon in June and July, the best time to see these high-altitude clouds. Noctilucent means “night-shining.” These clouds catch the sun’s rays long after all the others have faded to gray. More info here.  Bob King

To see a favorite planet or maybe a new comet in the night sky you might have to stay up late or get up early before sunrise. On other nights you may intend to get to bed but get caught up in the beauty and flow of the night and stay out way past your bedtime. Both happened to me.

I hoped to find a couple of comets early Tuesday night and sneak in a look at Jupiter from my dark-sky site but found it almost impossible to leave. First, twilight now lasts deep into the night. Where I live it doesn’t get dark until nearly midnight. What to do? Look at bright planets in the telescope and appreciate dusk’s slow pulse. The glow across the northwestern sky lingered so long I had all the time in the world to savor the changes in the color and tone of the sky and watch the stars come out in order of brightness. “Twilight watching” has to be one of the most relaxing pursuits on Earth.

Fireflies pop and swirl in this time exposure taken earlier this week. The colored sky is from airglow (see below). For a great guide to fireflies, get a copy of Lynn Faust’s Fireflies, Glow-worms and Lightning BugsBob King

Then there were the fireflies. In contrast to the honey-like drip of the night, hundreds flashed like electric sparks in the grasses that edged the bog. Males fly above the ground beaming characteristic patterns of light according to species. Females watch from the grasses below. Some zip by with a fast flicker, others flash three times in Morse-code like fashion. One of my favorites is Photinus pyralis which produces a sustained flash in the shape of the letter J, quivering as it rises. Females respond with a single flash if a male catches their fancy.

For sonics you can’t beat a summer night. Winter’s all about deafening silence (its own pleasure), but summer vibrates with life. American toads make the most beautiful trills — long, high-pitched and musical. If you listen closely you’ll hear different notes being sung by different toads. Blended, they create an eerie double-tone. Grunting green frogs sound like they’re gulping air, while mink frog calls recall the sound of horses’ hooves on cobblestones or knocking two stones together.

And the aromas. On the way to my site, the air smelled of balsam and pine, aromatics released from native trees by the heat of the day. Later, the bog oozed up chill hints of sulfur and an earthy sourness hard to describe. If I could have bottled it, one whiff and you’d know exactly what I mean.

Jupiter (right) and Saturn (left) straddle either side of the Milky Way, a sweet sight for those who stay out late. Bob King

Surprisingly, several types of birds sing at night including the occasional loud outburst of a white-throated sparrow, saw-whet owls (earlier in the season) and the mechanical and spectacularly repetitive sedge wren. One of the reasons birds sing at night is because there’s less noise as well as less vocal competition from other birds. Check out this excellent nocturnal guide with sounds files to help you identify some of the more common birds and frogs you’ll hear at night.

When we’re in the dark for a long time, interesting things happen inside our retinas. The rod cells, the ones used to see things in low light, finally reach their peak sensitivity after about 2 hours. Not only does this give you the ability find your way on the darkest night, but you’ll see the maximum number of stars. And the faintest of nocturnal glows. The most common is a natural form of light pollution called airglow.

Multicolor airglow streamers festoon the northern sky earlier this week. I enhanced the contrast (but not the color) on this image so you can make out the structures better. Bob King

Airglow looks like patches or streaks of smooth, grayish haze to the eye a good bit fainter than the Milky Way. On my night out, it filled the bottom of the Pegasus Square and vaguely illuminated a swath of the northern sky. Time exposures reveal green, red and orange colors too faint to discern with the eye.

Such diffuse bands of light can appear anytime of year. They extend from 50 to 400 miles (80-650 km) high in the atmosphere all over the planet, not just at high latitudes like the aurora. During the daytime, ultraviolet (UV) radiation from sunlight energizes molecules of nitrogen and oxygen at those altitudes. They “dump” that extra energy at night by emitting it as light causing the air to literally glow.

Another reason it’s hard to turn away from the sky and head back home is the primitive pleasure of watching the cycle of the stars. Early on late June evenings, the Milky Way stands partway up in the eastern half of the sky, but at 2 a.m., it’s nearly overhead. Cassiopeia hovers low in the north at 11 but tips up on its side by the wee hours. Stars in the west move along and disappear at the horizon, while fresh recruits rise up in the east, many unseen since last winter. Come 1 a.m. the fall constellations Pegasus and Andromeda are prominent in the east.

Can you see the Summer Triangle? It stands high in the southern sky during the early morning hours in late June. Deneb (left) and Vega are at top with Altair below. Together they make a big triangle about 3 fists tall. Bob King

I finally pulled myself away at 2. Packed the scope, got in the car and started home. I thought I was done, but turning left off a dirt road to head east, I wasn’t prepared for what happened next. A deep orange, last quarter moon stood directly over the highway centerline, hovering just a fraction of a degree above the roadway. Whoa ….

So many intoxicating sights, sounds and smells filled my head when it hit the pillow I laid awake for another hour. Next time, I’ll just stay up all night.