3I/ATLAS: Interstellar comet before closest approach to Earth

The interstellar comet 3I/ATLAS will pass its closest point to Earth this week during its journey through the solar system, but on Friday it will still be 270 million kilometers away. This offers instruments on Earth the best conditions for observing the visitor from outside, as highlighted by two images from late November. Those who wish to observe the approach live can do so, for example, via the Virtual Telescope Project run by Italian Gianluca Masi. He will stream astronomical images of the comet online. With more powerful instruments like the Hubble Space Telescope, the celestial body is expected to be observed for months to come.

More images again

3I/ATLAS was discovered in early July by the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Chile, hence its name. The interstellar comet is only the third visitor to our solar system to be discovered during its passage. On its trajectory through the solar system, it was behind the sun from Earth's perspective in the autumn. Therefore, probes from different parts of the solar system had to step in and take over the observation. It has also been visible from Earth again since early November. At the end of November, those responsible at the Gemini Observatory, for example, took advantage of this and took new images of the object.

On November 30th, Hubble also photographed it; the image was taken from a distance of 286 million kilometers. Before the weekend, the European Space Agency (ESA) then published an image of 3I/ATLAS in the X-ray spectrum, which was taken by the XMM-Newton space telescope. The X-rays detected in it originate from the interaction of the solar wind with various gases released from the celestial body. According to the ESA, the apparently noisy image is of great value for research because the instrument can detect and study gases that are difficult to identify with other devices.

While 3I/ATLAS is now on its way out of the solar system, another observation campaign is underway at the International Asteroid Warning Network (IAWN). The organization is actually dedicated to the international coordination of defense measures against asteroids that pose a potential threat to Earth. However, since the end of November, it has been responsible for the astrometry campaign. This involves the precise determination of orbital data, which is particularly difficult for comets. Participants will try to determine the orbital data as precisely as possible despite the tail until the end of January, after which the most successful methods will be discussed. This is intended to strengthen planetary defense in the future.

(mho)