Thursday, November 26, 2015

Double Rainbow Astrophotography Zion National Park

During my trip to Zion National Park, the weather was far from ideal for astrophotography. Clouds moved quickly across the sky, rain showers passed through the canyon, and the night sky remained hidden.

But sometimes nature offers something unexpected.

After one of the storms, sunlight broke through the clouds and illuminated the moist desert air. What followed was spectacular — a double rainbow stretching above the dramatic sandstone cliffs of Zion.

It made me pause and think: Is a rainbow astrophotography?

Technically, a rainbow is an optical atmospheric phenomenon caused by the interaction of sunlight with water droplets. The Sun — our nearest star — provides the light source. In that sense, this image captures a phenomenon directly created by astronomical light interacting with Earth's atmosphere.

So while it may not show stars, planets, or the Milky Way, it still documents a beautiful example of astronomy meeting atmospheric physics.

Double rainbow over Zion National Park after desert rain storm with sandstone cliffs illuminated by sunlight

Double Rainbow Astrophotography Zion National Park

Why Does a Double Rainbow Happen?

A primary rainbow forms when sunlight enters a raindrop, bends (refracts), reflects once inside the droplet, and exits — separating into colors.

A secondary rainbow appears when light reflects twice inside the droplet before exiting. This second internal reflection causes:

Reversed color order (red on the inside, violet on the outside)
A fainter and wider outer arc
A darker region between the two rainbows known as Alexander’s Band

Double rainbows are less common because they require:

Strong, low-angle sunlight (often late afternoon)
Large numbers of evenly distributed raindrops
The observer positioned with the Sun behind them

In desert environments like Zion, storms can be brief but intense — creating perfect conditions when sunlight returns.

Even though this was not the astrophotography session I had planned, this moment reminded me that sky photography is not limited to night. Sometimes the most powerful celestial light comes from the Sun itself.

Related Astrophotography & Sky Phenomena Posts

These posts explore how celestial light interacts with Earth’s atmosphere and environment — from atmospheric optics to interplanetary dust and extreme dark-sky effects.