This image of comet C/2022 E3 comes from the US space agency Nasa.
George NopperEditor News
Comet C/2022 E3 (ZTF) was discovered in March 2022 by staff at California’s Zwicky Transient Facility Observatory. Between January 12th and February 11th you will probably be able to see it with binoculars or even with the naked eye. Timm Riesen (46) from the Center for Space and Habitability at the University of Bern is one who is particularly close on the heels of C/2022 E3. Riesen is the director of the Stellarium Gornergrat. For Blick he clarifies the most important questions in connection with the sky spectacle.
What is a comet anyway?
A comet is a remnant of the formation of our solar system around 4.6 billion years ago. When the planets and their moons formed, some material was not integrated. “This is still in the form of comets in space,” says Riesen. According to the astrophysicist, comets are made of the same material as the planets. “You can think of a comet as a kind of dirty snowball, a lump of dust, rock and ice.” According to giants, when this comes to an orbit close to the sun, two tails usually form. A whitish dust tail and an ion tail always pointing away from the sun. “The dust tail is created by outgassing material when the comet heats up, and the ion tail is formed by the impact of the solar wind, which to a certain extent pulls the material with it.”
What is the difference to asteroids and meteorites?
“Comets, asteroids and meteorites are different celestial bodies,” says Riesen. Most asteroids are found in the asteroid belt between Mars and Jupiter. “Asteroids can be very large and, unlike comets, they don’t have a tail.” A meteorite in the classic sense is a part that enters the earth’s atmosphere and hits the ground. If the object just moves across the sky, it’s a meteor. A shooting star burns up when it enters the earth’s atmosphere, as the astrophysicist explains.
What is special about C/2022 E3?
This comet is among the brighter comets that have been observable in the last 30 years. You can calculate which track he must have had. According to this, C/2022 E3 was last at its closest point to the sun 50,000 years ago. “But you also know that its orbit will be significantly altered by Jupiter and Saturn, and by its own outgassing during its transit this year,” explains Riesen. “It is not yet possible to say whether the comet might even leave this solar system. We now have to observe which trajectory he actually follows after the passage.”
In the beginning, the comet was rather yellowish, according to Riesen. “It is now outgassing more – the heat ejects more molecules from the comet’s surface, which then interact with the sunlight.” In technical jargon, this interaction with sunlight is called photolysis. “This produces, among other things, C2 atoms, which are responsible for the green light.” The C2 atoms are broken down again after a few days. Therefore, the green light can be seen above all at the head of the comet.
How long does it take for light to travel from the comet to Earth?
“At the distance that the comet is from Earth these days, the light takes 5.8 minutes,” says Riesen. “In early February, when the distance to Earth will be minimal, only 2.4 minutes.” At this point, there are 42 million kilometers between the comet and Earth.
How can you see the comet?
“The best way to see it is with a telescope or good binoculars,” says Riesen. “If there is little moonlight, you might even be able to see it with the naked eye.” For a good view, however, the city light should also be avoided. On a star map or with an app you can orientate yourself by the constellation Northern Crown or further on by the carter and the constellation of the giraffe. The weather is initially rather unfavorable for comet fans on January 12, as meteorologist Klaus Marquardt (48) from Meteo News explains. “There will be quite a lot of clouds.” According to the forecasts, the sky will rarely be clear for the rest of the week. But visibility would improve. “In the next two to three weeks there will certainly be an opportunity to observe the comet,” says Marquardt.
When was the last time a comet was observable from Switzerland?
There are always comets to be observed by researchers and giants alike. “However, this requires special equipment in each case,” explains the astrophysicist. Comet C/2020 F3 – better known as Neowise – was last visible to the naked eye in the summer of 2020. This had a bluish ion tail pointing away from the Sun and a whitish dust tail. “Neowise also had a greenish rim on his head near the sun,” says Riesen. “But this was less pronounced than with the current comet.”