Double Arc of Aurora

An aurora arc (northern lights arc) is the most classic and stable form of the northern lights. It looks like a luminous bridge spanning the sky, usually in a faint green color.

Characteristics and origin

Shape: The arc follows the Earth's magnetic latitudes. When you see an arc, you are actually looking at a small part of the giant aurora oval that surrounds the Earth's magnetic pole.

Color: The most common color is yellow-green, which is created when electrons collide with oxygen atoms at an altitude of about 100–150 km.

Development: A quiet arc is often the starting point. If geomagnetic activity increases, the arc begins to "dance", form folds (curtains) or split into several bands

A double aurora arc (aurora borealis double arc) occurs when the northern lights split into two or more parallel bands that stretch across the sky from horizon to horizon. The phenomenon is particularly captivating because it creates a symmetrical and structured view of the otherwise often chaotic light show.

How they are formed:

Magnetic field lines: Particles from the sun are guided by the Earth's magnetic field down towards the poles. A double arc often forms when geomagnetic activity increases, causing the aurora oval to expand and split into several discrete bands.

Geomagnetic substorms: During the most active phases of a "substorm", a single arc can quickly split into several parallel arcs.

Perspective: To an observer on the ground, the aurora appears as an arc due to the curvature of the Earth and the distance from the light show.

On the left, the constellations Cygnus and Cepheus run through one of the most star-dense and interesting parts of the Milky Way in the northern sky. These areas are particularly popular for both observation and astrophotography.

The "Handle" of the Big Dipper is seen at the top right, consisting of three bright stars that form a curved line. These stars are part of the larger constellation Ursa Major.Here are the three stars in the handle, counting from the dipper outwards:Alioth: The brightest star in the entire dipper. It is closest to the "dipper" itself.Mizar: The middle star. It is known to be a double star. If you have good eyesight (or binoculars), you can see a smaller, fainter star right next to it called Alcor.Alkaid: The star that sits at the far end of the handle.