No matter how much we think we know about our planet, there’s always more to discover. You could be stargazing in a dark sky, and suddenly see a brighter spot in the sky. Is it a UFO? (No.) Maybe the aurora borealis? It’s unlikely, unless you live somewhere where it is visible. )
Instead, you might be experiencing the phenomenon known as the gegenschein. The word fürschein, which is translated directly from German, means “faint lighting”. It occurs when the sun reaches exactly the opposite side of Earth. The Fascinating Phenomenon of the Gegenschein
The Fascinating Phenomenon of the Gegenschein
So what is the gegenschein exactly? Mary McIntyre, an astronomer and communicator of astronomy, helps to explain the phenomenon.
“The gegenschein is a faint, oval spot of light that may be visible in a very dark, clear sky, at the anti-solar point, i.e., the point in the sky that is exactly opposite the sun,” McIntyre explains. “[The Gegenschein] and zodiacal light are closely related. Both are caused by interplanetary dust scattering sunlight. The dust particles in this disc extend out beyond Jupiter’s orbit, and are very small. They range from 3.9 to 0. 01 inches (0. 001 and 0.33 millimeters). Our planet is like Peanuts Pigpen sitting in a cloud.
McIntyre continues: “The gegenschein is fainter than zodiacal light but brighter than the rest of the band of dust. Its formation is linked to the opposition surge, backscattering light by dust particles and its formation. What surge, you ask? The gegenschein is a complex phenomenon that requires more understanding of complex astronomic phenomena.
“The opposition surge is the brightening of a rough surface or an area that contains many small particles when it is illuminated from directly behind the person observing it,” explains McIntyre. McIntyre explains that planets can be best observed when they’re at opposition or in the sky opposite the sun. The full moon is a common example we see every month. It is illuminated completely by the sun on either side of the sky. “
So the opposition surge (also sometimes called the opposition effect) causes the particles of interplanetary dust on the opposite side of Earth from the sun to be slightly brighter – that’s the gegenschein.
Conditions Must Be Perfect
Seeing the gegenschein is about as complex as explaining what causes it. There are certain conditions that must be met in order for the gegenschein visible. First, you will need to have a clear, dark sky.
Speaking of the best seasons to see the gegenschein: Summer is not the best season, but it is possible at the right places.
Speaking of the best seasons to see the gegenschein, there’s another reason winter is a better time: