Jupiter, the largest planet in the solar system, continues to amaze, and so does the Webb telescope. Infrared photos show something that has not been observed before. In addition, the coming weeks are a perfect time for backyard observations of this planet.
Jupiter was the first planet in the solar system toward which the Webb Space Telescope looked as it prepared for regular observations. The test photos of Jupiter were already impressive, but then the telescope and its NIRCam instrument outdid themselves. The observations were made in July 2022, but the results of the data analysis have only now been revealed. They are accompanied, as always, by a beautiful photo of Jupiter.
Burning poles and something unusual in the center of Jupiter’s disk
The colors of the planet in the photo are, of course, unnatural, but this is a consequence of the different observation bands than the visible ones, and the colors were selected to best reflect the nature of the visible details. And what we see in the photo. The north and south poles appear to be on fire, and these are precisely Jupiter’s auroras.
The bright spots and streaks visible on cloud bands are in practice the highest cloud layers that accompany convective storms on Jupiter. According to the image description, the dark bands that are particularly visible in Jupiter’s northern hemisphere are areas where cloud cover is relatively low and sparse.
But these weren’t the surface details that interested astronomers most in the latest Webb image. This is something that only Webb could see, although we have been closely observing the planet for decades, and it was seen closely not only by the passing Voyagers and Cassini-Huygens, but also by the Juno probe, which is still exploring the Jupiter system.
That surprising detail is the jet stream, which now appears as a distinct streak above the planet’s equator in near-but-farther-infrared images than before. Previous observations indicated their potential existence, but because they reached deeper into the clouds, evidence of jet streams was very fleeting. Now, as astronomers who observe Jupiter through Webb point out, these details are so clear that their properties can be well determined.
The jet streams occur at an altitude of 20 to 35 kilometers above the main cloud cover in Jupiter’s lower stratosphere, and their speed reaches 515 km per hour. That, NASA compares, is twice as fast as the wind speed in class F5 tornadoes (theoretically the strongest possible). In Poland, hurricanes blowing at a speed of 150 km/h are already considered to have disastrous consequences.
Webb discovered, but Hubble was useful to get it all right in his head
The jet structure observed by Webb, associated with the jet stream, is 4,800 kilometers long. This is a lot for us, but since Jupiter has a circumference of 439,264 km (11 times larger than Earth), it is small in the image of Jupiter. Jupiter was observed approximately every 10 hours to see how the current behaves and affects its surroundings.
Thanks to additional observations from the Hubble telescope, at other wavelengths, it was possible to create a spatial model of the behavior of the jet stream and its effect on the cloud layer. Astronomers want to observe Jupiter periodically over the next few years because they predict that the behavior of the jet stream may be linked to changing wind and temperature patterns near Jupiter’s equator.
What Webb achieved was observational astronomy of the highest order, unattainable for amateurs. However, this does not mean that we can only admire the otherwise beautiful photos of Jupiter from Webb and other large observatories. The cloud pattern on Jupiter’s surface can be captured by an advanced astrophotographer. In turn, even simple binoculars will allow you to see something unusual around Jupiter. Now is an exceptionally good opportunity to do so.
Jupiter closest to Earth, brightest in months. This is not to be missed
Jupiter is a beautiful object to admire at any time of year when it is visible in the sky. Of course, we must remember that its distance from Earth changes significantly and this translates into approximately a two-fold change in Jupiter’s angular size in the sky. When it is on the opposite side of the Sun from the Earth, its distance from the observer is up to 968 million km, and when it is on the same side, it is in opposition and at the same time extremely close to the Earth, i.e. at a distance of up to 588 million km.
On November 1, 2023, two days before opposition, Jupiter will be closest to Earth in 2023, at a distance of 595 million kilometers. Jupiter will be similarly close to Earth only in 2033.
The moment of opposition will come in less than two weeks. On November 1, Jupiter will be closest to the Earth, and two days later at opposition, i.e. exactly on the extension of the Sun-Earth line, and its disc will be illuminated to the greatest possible extent. In addition, on November 7, Jupiter will reach its highest height above the horizon around 11 p.m., and the Moon will only rise at this time, so these will be additionally favorable conditions for observations.
Jupiter’s height above the horizon on the night of October 21-22. (photo: Stellarium)
For the next few months, Jupiter will be in the constellation Aries, and the closest characteristic point is the Pleiades cluster located to the left of the planet. Currently, Jupiter rises around 6 p.m. and rises at 1 a.m. After the time change on October 29, these will be earlier hours.
Jupiter at opposition, but also for many days before and after November 3, shines with a brightness close to magnitude -2.9 (about as bright as the passing International Space Station, only Venus and the Moon are brighter). Therefore, whenever the weather is good, reach for your observation instruments.
Orientation map, with Jupiter’s position above the southeastern horizon at 11 p.m. in late October. (photo: Stellarium)
Even an amateur can see Jupiter’s moons and cloud bands
The amount of detail you will see depends on how much magnification your instrument provides. Even binoculars with a magnification of 7 to 10 times will allow you to see the Galilean Moons, four distinct dots surrounding Jupiter in almost one line. Their position changes rapidly, from day to day, and in the case of the nearest Io, even within hours (it takes less than two days to complete its orbit). Next, Europa and Ganymede, orbit the planet with periods of 3.5 and 7.1 days. Callisto, the most distant moon discovered in 1609, changes its position the slowest, over a period of over 16 days. Tracking changes in their relative positions through binoculars gives an incredible feeling of the dynamics of this mini planetary system in the Solar System.
In the case of Jupiter, when we talk about surface observations, we mean the uppermost layer of clouds that is visible from Earth at a given wavelength. The clouds above are too thin to obscure the view, and the clouds below are so thick that they do not obscure the interior of this gas giant.
If, on the other hand, you have a stronger instrument, a telescope/telescope with a magnification of about 100 times and a lens/mirror diameter of about 10 cm, you will be able to see bands of clouds. Not as spectacular as in the photo from Webb, but I guarantee that the satisfaction will be even greater.
It must be remembered that not only magnification plays a role here, but also the ability of our instrument to collect light. Therefore, the mentioned combination of magnification – diameter of the input element is necessary. Of course, this is a combination for comfortable observation, with a lower magnification of about 50 times and a several-centimeter aperture of your instrument, there is also a chance to see something on its surface.
Source: NASA/ESA/Webb, inf. own
2023-10-21 18:53:56
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