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.

Moon & planets

A cold, colorful afternoon in Vallentuna, Sweden. In the sky, a thin crescent moon with earthshine is visible, and to the left of the moon, the planet Saturn, and to the lower right, the planet Mercury.

Earthshine is an astronomical phenomenon in which sunlight is reflected from the Earth onto the dark night side of the moon, making the entire lunar disk faintly visible even when only a thin crescent is directly illuminated by the sun.

Mercury is the smallest planet in the solar system and the one closest to the sun. It is a rocky, so-called terrestrial planet with a surface filled with craters, which makes it very reminiscent of our moon.

Saturn is the second largest planet in the solar system and is best known for its spectacular and complex ring system. It is a gas giant that consists mainly of hydrogen and helium.

Where life once evolved.

 A clear and cold night by the sea on planet Earth. In the sky, the constellation Orion is visible with the star factory Orion Nebula under Orion's belt, visible to the naked eye. Our star Sun was probably created from a similar star factory long ago. The Orion Nebula (M42) consists primarily of gas and dust, where the absolutely dominant elements are hydrogen and helium. It is an emission nebula that shines because young, hot stars ionize the gas.

The Earth formed about 4.6 billion years ago from a rotating disk of gas and dust that surrounded the young Sun. By clumping together pebbles and cosmic dust, the planet grew. Originally, the Earth was a red-hot melt that cooled and formed a solid crust. Water was added later, probably via comet impacts. The theory of the origin of life is that life on Earth arose in the ocean about 3.5–3.8 billion years ago, probably in close proximity to hot springs on the seafloor where amino acids and simple bacteria were formed. The ocean served as a protective environment for the first organisms before oxygen and the ozone layer made life on land possible. The oldest traces of life are 3.5–3.7 billion years old and are found in marine environments. Early theories focused on the "primordial soup" in shallow sea bays, while more recent research often points to hot springs (hydrothermal vents) in deep water. Complex organic molecules (amino acids) formed in the water and assembled into simple bacteria. These first organisms were independent of oxygen, but later began to produce it through photosynthesis. Evolution started with simple microorganisms, followed by algae, and later the first multicellular animals developed in the sea. The picture shows algae and seaweed that fluoresce via UV light. They are clearly visible thanks to the current record low sea level. Algae contain chlorophyll for photosynthesis. When chlorophyll is hit by UV light or blue light, it absorbs the energy, but cannot use it all. The excess energy is emitted as a red or pink glow. This is called fluorescence and can often be seen underwater with special lighting or when analyzing algae. Under Orion, light pollution from civilization is seen, life has developed into an intelligent species Homo Sapiens Sapiens that eventually invented electricity. The place where the picture was taken, Nothamn Sweden, is known for its geology, 1.9 billion years ago there were explosive volcanoes here that spewed ash and lava over a shallow sea that covered the area. Early forms of life, microorganisms, lived on the seabed, which together built up limestone layers. Iron precipitated in the limestone and layers of iron ore were formed, something that is common throughout Bergslagen. Deep down, beneath the volcanoes, large magma chambers have solidified into the rocks diorite and gabbro. So the rocks in the picture were created during this time.