Glowing clouds and a special „visitor“ over Bonn Comet appears in the night sky over Bonn and the region

Bonn · Noctilucent clouds fascinate regional sky watchers in early July. Here’s what’s behind the phenomenon and where early risers can observe a comet.

 In 2019 the comet PanStarrs was visible in the sky.

In 2019 the comet PanStarrs was visible in the sky.

Foto: AP/dpa

During the short nights at the beginning of July, two special phenomena appear in the night sky over Bonn and the region. With binoculars you can see the comet Neowise at dawn until the middle of the month. First photos are already shared on the net.

Like a bright stripe with two tails the comet Neowise can be seen in the morning sky on a photo on the blog "Bonner und Bochumer Sterne". On this page hobby astronomers present their observations. The Roisdorf astronomer Michael Geffert explains exactly what is hidden behind it: "Now observers have the best chances to see this comet". With the naked eye it is probably difficult to recognize it, therefore Geffert gives the advice: "It would probably be good to go out with binoculars. "But you should never look directly at the sun with binoculars."

Neowise C/2020 F3 can be seen in the sky

He points to the sun because the comet can be observed at dawn. Sunrise for Tuesday, July 7th, meteorologists indicate at 5:28 am. At about this time - better a little earlier - it is usually worthwhile to look at the sky in a northeastern direction. Geffert says: "At about the height of the constellation Carter, the Neowise will be visible." Photos of the comet can be found on the web under the code C/2020 F3 Neowise. Often comets are rather invisible, says Geffert.

This one orbits the sun once every 7000 years. Geffert adds: "From Earth, about 30 comets are observed each year." From the middle of July, C/2020 F3 will have moved on and can be expected in the night sky between the constellation lynx and the big bear.

Die schönsten Wolken-Fotos der GA-Leser
9 Bilder

Die schönsten Wolken-Fotos der GA-Leser

9 Bilder
Foto: Oliver Poschwatta

Clouds that glow during the night

Although the sun may still be far from rising, clouds currently glow over Bonn and the region at night. This is shown by photos by Bonn residents, who discuss the phenomenon of noctilucent clouds on social media. But how is it possible that the webcam of the Bonn weather service Donnerwetter.de recorded a large white-green glowing spot in the sky at 3.15 am on 20 June?

For Karsten Brandt, the managing director, this is no mystery. He is more pleased about the snapshot that the device accidentally took while he himself slept in bed. Normally, the night shots Brandt regularly looks at are dark. But the stain was unusual. Brandt says, „You might think the clouds would light up on their own, but of course they don't." And they're not really clouds that appear in the night sky at high altitudes. About 80 to 85 kilometres above the Earth's surface in the mesosphere, ice crystals create the effect of noctilucent clouds. According to a report from Donnerwetter.de, temperatures of minus 100 degrees Celsius prevail there.

Noctilucent clouds consist of ice

Astronomer Geffert also knows the light effect and refers to the meteorologist for an explanation of the phenomenon. Such near-earth layers are rarely studied by the discipline interested in celestial bodies. And the distance is also unusual for Brandt: "These phenomena normally play no role in weather forecasting," he says and sees a need for research.

What is clear is that when the sun is at a certain angle to the earth, it illuminates these ice crystals - as long as they are at this extraordinary altitude. This is how the glow comes about, says Brandt, and gives all those who like to spend their summer nights outdoors hope for unique observations: "The glow can take on different colours. But sometimes these noctilucent clouds also look like cirrus clouds to the layperson - only much higher up in the sky. They can be seen especially in summer, because only in these weeks the sun is at the appropriate angle above the region.

Light pollution makes observations difficult

For both observations it is important to find a rather dark place. This is also confirmed by Geffert, who is concerned about light pollution. The many lights in the cities not only make it difficult to observe the sky, he says. They also affect the insect world: "Light pollution is also a form of environmental pollution," he says. That's why observers from the Siebengebirge mountains can probably see the comet better than those who look up at the sky from Bonn.

(Original text: Anja Wollschlaeger / Translation: Mareike Graepel

Meistgelesen
Neueste Artikel
Zum Thema
Aus dem Ressort