The photo shows the rarely seen south pole of the planet, which turns surprisingly blue.

Space telescope Hubble has delivered a beautiful picture of gas giant Saturn. The photo can be seen below. You may wonder why that is still special, because we don’t know what Saturn looks like in the meantime? That is partly true, but there is still so much that we do not know about this special planet. And this snapshot also provides new insights.

Since space probe Cassini was launched in 1997 and arrived at Saturn in 2004, we have been regularly treated to beautiful images of the sixth planet in our solar system. However, that came to an end in 2017 , when the probe’s fuel began to run out and bore into the gas giant’s atmosphere as planned. It meant that we would – at least in the coming years – do without close-up images of this beautiful system. Fortunately, we still have the powerful Hubble space telescope. And he occasionally keeps an eye on Saturn – albeit from a much greater distance than Cassini. Among other things, it results in this new snapshot that was produced in early July and that NASA recently released.

Newly crafted depiction of Saturn. 
Two of Saturn’s freezing moons are clearly visible: Mimas on the right and Enceladus on the bottom. 
Image: NASA, ESA, A. Simon (Goddard Space Flight Center), MH Wong (University of California, Berkeley), and the OPAL Team

The photo shows the lush and gigantic planet that was about 1.35 billion kilometers from Earth at the time of the photo (for comparison, that is, 30,000 times around Earth). Hubble photographed the gas giant in the Northern Hemisphere during the summer. “The image is actually a composite image of three different photos each in a violet (395 nanometer), green (502 nanometer) and red (631 nanometer) filter,” researcher Amy Simon tells . “We always use filters to obtain specific wavelengths of light, based on what we study. To create a color image, we have to combine them to approximate the true color. That is why the colors are a bit more exaggerated than what you would see with your own eyes. ”

According to the researcher, getting new photos of Saturn is very important to our understanding of the planet. “A few years ago, we realized that it was difficult to properly understand and model the atmosphere of some planets in our solar system because we had only recently studied it,” says Simon. “Every now and then Hubble takes a look and space missions like the one with Cassini are rare. That is why we have launched a project in which we produce images of planets with Hubble every year. In this way we want to understand how their clouds, wind and weather change over time. Because Cassini was still in operation at the time, we only started observing Saturn with Hubble in 2018. Cassini then uncovered the seasonal changes of the gas giant. And we are now building on that. By observing the planet for longer, we can begin to untangle all discovered properties and how they change the atmosphere. ”

Cloud bands
Hubble captured a number of small atmospheric storms raging on Saturn. “These are bright spots, for example, one is just above the center of the image,” says Simon. The storms that rage across the planet seem to come and go every year. In addition, when viewed from space, Saturn’s atmosphere exhibits a pattern of stripes or bands similar to that of neighboring planet Jupiter. However, the difference is that Saturn’s bands are more blurred and much wider around the equator. The Northern Hemisphere tires in particular stand out in the photo, which change color slightly from year to year. “You can see that the edges of the cloud bands are sometimes wavy, because the jet streams meander slightly,” explains Simon. “Also on the North Pole is the hexagon of Saturn (a hexagonal cloud pattern with a strong storm in the center, ed.) Although it is more difficult to see in the picture.” The ringed planet’s atmosphere is primarily composed of hydrogen, helium and traces of ammonia, methane, water vapor and hydrocarbons. These give the planet the yellow-brown color.

The newly made image shows how colorful Saturn is. For example, Hubble photographed a light, reddish haze across the Northern Hemisphere. “This may be due to an increase in mist and aerosols, as sunlight interacts with the atmosphere,” explains Simon. In addition, the small visible portion of the planet’s south pole shows a blue hue, reflecting the changes in Saturn’s winter hemisphere. “That blue color was a nice surprise to me,” says Simon. “When Cassini arrived at Saturn in 2004, the North Pole was just blue and gradually yellowed as the seasons changed. But in the new photo, it is winter at the South Pole. We haven’t seen that with observations from Hubble in the past two years, because the rings blocked our view of the South Pole. We are still not entirely sure what causes that light blue discoloration. It could be a change in the amount of aerosols produced by the sun, or it could be due to changes in temperature and circulation. ”

Seasons on Saturn

Saturn is also subject to seasons. The gas giant has a tilt of 27 degrees to the sun. This tilt is similar to that of the Earth, which has an angle of about 23 degrees to the Sun. This tilt causes the seasons: in the hemisphere that is tilted towards the sun, it is summer. However, the seasons last a lot longer on Saturn than on Earth. The planet takes about 28 years to complete a circle around the sun. This means that each season lasts about seven Earth years. At the same time, Saturn also orbits in a slightly tilted orbit around the sun (not the earth), which also influences the amount of sunlight that a hemisphere receives. In addition, while the rings look light and airy, they also cast a shadow on the planet.

The photo also takes a fresh look at Saturn’s rings, which are quite up for debate. “We see slight color variations in the rings,” says Simon. “We think that some rings contain more dust, even if they mainly consist of pieces of water ice. It will be interesting to take a closer look over time and compare it with previously produced images by Cassini. ” What we know is that the rings consist of pieces of ice, ranging from very small grains to gigantic chunks of rock. How and when these rings are formed remains one of the greatest mysteries in our solar system. The generally accepted theory about the age of Saturn’s rings is that they originated about 4.5 billion years ago, in the early years of our solar system.the rings were much younger than expected . The argument was that the rings were too white and too bright and actually looked too ‘clean’. If the rings were much older, collisions with meteoroids would have made them dirtier. It would mean that Saturn’s rings were formed only a few tens of millions of years ago, around the time dinosaurs roamed the Earth. But it may also be that the rings actually look much younger than they actually are . Researchers are therefore not yet out. Hopefully future research will provide more insight.

The researchers hope to do more research to get to know Saturn a little bit better. “By collecting more data, we hope, for example, to understand how different jet streams and cloud bands change over time,” says Simon when asked. “The equator has become much brighter and whiter in recent years.” Yet it is not so easy to get more clarity on this. “Because of Saturn’s tilt, our view of the planet is constantly changing. For example, the rings block our view of different parts, regardless of the seasons. All this makes it extremely challenging to study the atmosphere properly. However, Saturn will revolve in the near future, giving us the best view of the rings in 2025 and 2026.

In addition, the researcher is looking forward to another mission to Saturn and its moons. “There are still many mysteries that require a mission to get to grips with,” she says. The first concerns the planet’s origin and whether Saturn, for example, formed at the same time as Jupiter. This requires direct measurements of the composition of the atmosphere. In addition, Saturn naturally has some fascinating moons, such as Titan and Enceladus. For example, we want to study the possibility of an underground ocean on Enceladus. And for that you have to get very close to the surface. ” Although a new mission to Saturn itself and moon Enceladus may take a while, a mission to Titan is in the offing. NASA plans to explore the unique and richly organic world of Titan pay a visit in 2026 . And with a real drone, which is called Dragonfly. The drone is not expected to arrive at the moon until 2034. Dargonfly is supposed to visit several promising locations on Titan and look for prebiotic chemical processes. The atmosphere of Titan will also be examined, as well as underground ocean and lakes. It therefore promises to be an extremely interesting mission, which can also teach us a lot about the origin of life itself. Meanwhile, research into Saturn is also continuing. Because there is still plenty to discover about this gas giant.

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