An interstellar comet first spotted passing through our solar system in July is beginning its departure from our corner of the universe, but first it will fly past Earth, and scientists are capturing stunning new images as it approaches.
The comet, known as 3I/ATLAS, will pass us on Friday at a distance of about 167 million miles (270 million kilometers) from our planet, but on the other side of the Sun. For reference, the distance of the Sun from Earth is about 93 million miles (150 million kilometers).
Comet 3I/ATLAS will not be visible to the naked eye, and the optimal viewing window that opened in November has already passed. Those hoping to see it will need an 8-inch (20 centimeter) telescope or larger, scientists say. EarthSky.
The Virtual Telescope project will share live broadcast comet at 4:00 a.m. UTC Friday or 11:00 p.m. ET Thursday. In case of cloudy weather, the webcast will be delayed by 24 hours, said Gianluca Masi, an astronomer and astrophysicist at the Bellatrix Astronomical Observatory in Italy and founder and scientific director of the Virtual Telescope project.
The comet is expected to remain visible to telescopes and space missions for several more months before leaving our solar system. NASA.
Astronomers have been closely monitoring the comet since its initial discovery in the summer, hoping to uncover details about its origins outside our solar system, as well as its composition. Several missions have observed the object in optical, infrared and radio light, and recently scientists captured it for the first time in X-rays and discovered new details.
X-ray image of an interstellar guest
Comets that originate in our solar system emit X-rays, but astronomers have long wondered whether interstellar comets behave the same way.
Although previous attempts to find out were made when two other interstellar comets passed through our solar system in 2017 and 2019, no X-rays were detected.
But everything changed with the advent of 3I/ATLAS.
Japan's X-ray Imaging and Spectroscopy Mission (XRISM) observed 3I/ATLAS in late November for 17 hours using its Xtend telescope. The instrument detected X-rays extending as far as 248,000 miles (400,000 kilometers) from a solid or cometary core, which could be the result of clouds of gas around the object, according to the data. Japan Aerospace Exploration Agency. But additional observations are needed to confirm this conclusion.
XRISM captured an image of Comet 3I/ATLAS in X-ray light. – JAXA/ESA
X-rays can be produced by the interaction between gases emitted by a comet, such as water vapor, carbon monoxide or carbon dioxide, and a continuous stream of charged particles emitted by the Sun, called the solar wind. Comets, which are a mixture of ice, rock, dust and gas, heat up as they approach stars like the Sun, causing materials to sublimate. XRISM detected traces of carbon, oxygen and nitrogen near the comet's nucleus.
The European Space Agency's XMM-Newton X-ray space observatory also observed the interstellar comet on December 3 for about 20 hours with its most sensitive camera. The dramatic image released by the agency shows the comet's red X-ray glow.
X-ray observations, combined with other observations at different wavelengths of light, can reveal what a comet is made of—and how similar or different the object is to objects in our solar system.
Register for CNN Science Newsletter Wonder Theory. Explore the universe with news about exciting discoveries, scientific advances, and more.
For more CNN news and newsletters, create an account at: CNN.com
