The Science of Sunsets

The science

of sunsets

Why are Cape May’s winter sunsets so dramatic, and what’s that green flash you might just catch during the last dip of orange? These questions answered, and more.

article lynn martenstein photography laura thistle

Cape May’s sunsets often bring people to a standstill. Drivers brake, bikers back-pedal, power walkers power down. On more nights than not, nature puts on an unmissable light show over our town—and winter brings the best spectacle of all. Luckily, being on an island, we get an unobstructed view. To help you enjoy the show even more, we’ve put together some fun facts from science, pop culture and Cape May traditions that may cast sunset in a whole new light for you.

First, the Science

Think you’re seeing red at sunset? Sunlight is made up of all of the colors of the rainbow. At sunset, the atmosphere scatters the bluish light we see during the day (aka the blue sky) but lets the reddish hues pass straight through. We’re also able to look directly at the sun at sunset—a no-no during the day.

You probably think of sunset as when the last sliver of sunlight sinks below the horizon, maybe when you’re sitting in one of the Adirondack chairs on Congress Hall’s Grand Lawn, for instance. But the sun’s light is refracted by the earth’s atmosphere, so while you’re tracking the sun’s downward path, it’s already gone below the horizon. What you see is happening eight minutes after the fact.

Sunset, dusk and twilight are not created equal. The time after the sun sets is called twilight, which ends at dusk when the sky goes completely dark.

Places north of the Arctic Circle and south of the Antarctic Circle have at least one day a year without a sunset or sunrise.

Not to be confused with a Marvel Comics hero, the elusive green flash that occasionally appears in that split second as the last of the sun’s rays dips below the horizon is the normally obscured green light in the middle of the sun’s color spectrum. The optimal conditions for a sighting of a green flash are a clear evening and an unobstructed view of the horizon.

The sun sets due west (and rises due east) only two days a year: the vernal and autumnal equinoxes. Slowly changing every day, the sun sets south of due west in fall and winter, and north of due west in spring and summer.

Cape May’s promenade runs east to west near the Cove. When we view sunsets from there in winter, the sun is setting directly over an unobstructed horizon, casting a bright orange glow over the beach and promenade. From the same vantage point in summer, the sun is setting over land, diminishing that effect.

Former astronaut John Glenn, the first American to orbit the earth, witnessed four “beautiful sunsets” on his historic journey in 1962. Astronauts on the International Space Station see 15 or 16 daily today.

The saying, “Red Sky at Night, Sailors’ Delight, Red Sky in Morning, Sailors’ Warning,” is based on fact. A red sky at night may indicate that the sun’s light is passing through dust particles, meaning a high pressure system or fair weather is coming from the west. A red sky in the morning may signal a low pressure system, aka not-sogreat weather heading our way.

Cape May Magic

Because we’re located at the tip of a peninsula, Cape May is one of the few places in the world where the sun both rises and sets over salt water. Our sunsets are so beautiful partly because the air is so clean here. Pollution in the atmosphere can mute vibrant colors—not a problem on the Cape.

The flag-lowering ceremony at Sunset Beach has elevated sunsets to required watching. In July and August, hundreds of people gather to pay tribute to a departed US veteran as the flag that draped his or her coffin is reverently lowered to taps and Kate Smith’s classic rendition of “God Bless America.” Reservations to fly a family member's flag usually open at the beginning of May each year, and often are filled within an hour.

In the fall, our sunsets are even more spectacular. That’s because the air tends to be drier, meaning there are fewer moisture particles to scatter those red and pink wavelengths before they reach the eye. Another reason to make a return trip to Cape Island when the temperatures cool.

The Perfect Perch

Due to the sun’s pivot throughout the year, it’s possible to see both sunrise and sunset while standing at Congress Hall’s beloved flagpole between early November and early March of every year.

Don’t believe us? Stay overnight at Congress Hall this holiday season and see for yourself. It’s quite the phenomenon.