It has often been likened to talcum powder. The ultra fine lunar surface material known as the regolith is crushed volcanic rock. For visitors to the surface of the moon it can be a health hazard, causing wear and tear on astronauts and their equipment, but it has potential. The fine material may be suitable for building roads, landing pads and shelters. Researchers are now working to analyze its suitability for a number of different applications.

Back in the summer of 1969, Armstrong and Aldrin became the first visitors from Earth to set foot on the moon. Now, 55 years on and their footprints are still there.

At 35,000 feet over the U.S. the air was thick with anticipation and excited chatter as everyone pulled out their phones hoping to get a photo.

Gray shadows entered the blue sky, turning it a rich slate as the moon started to eclipse the sun.

The moment everyone had been waiting for was here—totality.

Before even getting into the air Delta Air Lines treated passengers to an experience. As they arrived at gate E15 at Dallas Fort Worth International Airport for Flight 1010 to Detroit, they were met with a celestial-themed balloon arch, a red carpet and music.

Flight attendants in purple and gray passed out eclipse-viewing glasses the airline produced in collaboration with Warby Parker—paper shades but with blue-and-white star path drawings on the front and "Eyes on the Sky" written inside.

Delta workers wore T-shirts emblazoned with "Climbing the Cosmos," the airline's slogan for the pair of flights from Austin and Dallas that would be in the path of the eclipse 35,000 feet in the air.

People were excited, and the gate party only heightened the anticipation. Most passengers flew to Dallas that morning or the night before just to turn right around, all to experience totality in a way few others could.

After beholding the midday darkness of a total solar eclipse that raced across the continent, thousands of spectators in New England were stuck seeing only brake lights Monday night as highway traffic backed up for hours.

Crowds of motorists leaving remote northern New Hampshire in the late afternoon clogged local roads leading to Interstate 93, which they found also thronged by cars inching southward. By midnight, some drivers had traveled only 50 miles (80 km) in nine hours.

The New Hampshire Department of Transportation urged patience and said there were about 22,000 more vehicles visiting the tiny state compared to the same time last year. Heavy traffic was also reported in Vermont and Massachusetts.

Whether you saw the moon completely block the sun, were foiled by cloudy weather or weren't along the path of Monday's total solar eclipse, there are still more chances to catch a glimpse.

Here's what to know about upcoming solar spectacles:

When is the next total solar eclipse?

Total solar eclipses happen about every year or two or three, due to a precise alignment of the sun, moon and Earth.

The day died and was reborn a few minutes later Monday in the southern United States. There were hugs, tears and gasping as people watched the moon fully eclipse the sun and briefly plunge the world into darkness.

About 2,000 people flocked to Ingram in the southern US state of Texas, a small city in the "path of totality" where the solar eclipse could be observed in its entirety.

Spread on mattresses on the grass, sipping wine comfortably from folding chairs or peering into large telescopes, the viewers, their eyes covered by special protective glasses, celebrated each time the gray clouds parted, letting them enjoy the wonder.

"Three, two, one!" a man shouted.

And there was the moon, a black orb completely covering the sun, with only tiny slivers of light escaping from the edges.