According to the International Astronomical Union (IAU), Jupiter has 79 known moons, but finding these tiny celestial bodies orbiting the gas giant is a challenge, as many of them are small and reflect little sunlight – or do so for a short period. of time. Despite this, thanks to publicly available data from several Earth telescopes, amateur astronomer Kai Ly has discovered a new natural Jovian satellite, which, while not yet officially designated, has a good chance of increasing the number. from the moons of Jupiter to 80.
The amateur astronomer reports that she began planning her mission to search for moons on Jupiter in May of last year, but it was in June that she began examining data obtained in 2003 through the Canada-France-Hawaii (CFHT) telescope with 3 .6 meters in diameter, located in Hawaii. The images obtained at the time were the same ones used by astronomer Scott Sheppard, of the Carnegie Institution for Science, who, in 2018, discovered 12 new moons on Jupiter, bringing the total number of them to 79.
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Image analyzes before the new discovery suggested that more moons might be hidden in this dataset taken in 2003. So Ly began studying images from February of that year, when Jupiter was in opposition – that is, aligned with the Earth and the Sun – and its natural satellites appeared brighter in observations. Of the 36 records made on the 24th of that month, 19 were examined, leading to the discovery of three potential moons, which moved between 13 and 21 seconds of arcs per hour during the night.
Because they were small, Ly couldn’t find two of these moons in later observations. However, she found the third, tentatively named EJc0061, in research logs between February 25 and 27, and also in images taken on February 5 and 6 with the Subaru Telescope, located at the Mauna Kea Observatory. , in Hawaii. The arc of days indicated that the object was linked to Jupiter.
As a result, Ly had enough data to look for the orbit of this potential moon in images taken from March 12th to April 30th (as of 2003). “From then on, the quality of the orbit and ephemeris was decent enough for me to start researching observations after 2003,” he adds. Confirmation of the satellite’s predicted position came through images from the Subaru Telescope, the CFHT and the Cerro Tololo Inter-American Observatory, taken until early 2018. With very low brightness, the moon’s magnitude varies between 23.2 to 23, 5. The magnitude scale works like this: the smaller the number, the brighter the brightness. As an example, the planet Venus, which appears just after sunset at this time of year, has a magnitude of -3.8. In other words: 23.3 is a very weak glow.
At the end of the analysis, the amateur astronomer obtained an arc of 76 observations spread over a period of 15.2 years (approximately 5,574 days) – enough for Ly to consider the moon’s orbit well demarcated. The satellite, temporarily named S/2003 J24, is now awaiting official confirmation. For David Thlen, from the University of Hawaii, the information is enough to show that it is a moon. “It would be nearly impossible for artifacts to fit into a jovicentric orbit on so many different nights using different cameras,” adds Tholen.
The discovered moon is part of a group of 22 other satellites known as the Carme Retrograde Group, which orbit Jupiter in the opposite direction of the planet’s rotation, in periods of up to two years. Experts believe that this group may still have many more companies waiting to be discovered. For Ly, it is a pride to be able to say that this is the first moon discovered by an amateur astronomer. Thanks to public data made available by observatories, the trend is that more amateur astronomers will have the same pleasure as Ly discovering a moon in the Solar System.
Ly’s full account can be accessed here, as well as a compilation of images of the new moon she has assembled.
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