A bright โgreen cometโ roughly the size of a small city is set to make its closest approach to Earth next week.ย Scientists say it may eventually be ejected from the solar system โ never to return.
The comet, officially designated C/2024 E1 (Wierzchoล), was discovered in March 2024 by Polish astronomer Kacper Wierzchoล using a 1.5-meter telescope at the Mount Lemmon Observatory.
Follow-up observations by the James Webb Space Telescope detected large amounts of carbon dioxide in the cometโs coma โ the cloud of gas and dust surrounding its icy nucleus โ helping scientists better understand its composition.
How big is it?
Initial analysis of Webb data estimated the cometโs nucleus at about 8.5 miles (13.7 kilometers) across โ roughly two-thirds the length of Manhattan. However, a newer study that has yet to undergo peer review suggests the size may have been overestimated.
Even with a revised estimate, researchers say the comet remains a substantial icy body by solar system standards.
A visitor from the outer solar system
Astronomers believe the comet originated in the distant Oort Cloud, a vast spherical shell of icy objects at the edge of the solar system.
Unlike short-period comets that regularly orbit the Sun, C/2024 E1 follows a hyperbolic trajectory โ meaning it travels on an open path and does not return after passing through the inner solar system. Scientists suspect this is likely its first visit near the Sun.
Some researchers estimate it has been falling inward for between 1 million and 3 million years. But its current close encounter with the Sun may provide the gravitational โkickโ needed to eject it entirely from the solar system.
Closest approach
The comet reached perihelion โ its closest point to the Sun โ on January 20, coming within about 52 million miles (84 million kilometers) of the solar surface.
Scientists expected it to make its closest approach to Earth on February 17, when it will be about 94 million miles (151 million kilometers) away โ roughly the same distance as Earth is from the Sun.
While not a threat to the planet, the comet could be visible to observers with telescopes under favorable sky conditions.
A one-way trip?
If gravitational forces send it beyond the Sunโs pull, C/2024 E1 could spend millions or even billions of years drifting through the Milky Way, occasionally passing near other star systems.
That would mirror the path of 3I/ATLAS, an interstellar comet that made headlines last year after racing through the inner solar system. Some scientists briefly speculated about artificial origins, but observations overwhelmingly confirmed it was a natural object.
For now, astronomers are closely monitoring C/2024 E1 as it makes its swing past Earth โ a rare glimpse of an ancient traveler that may soon leave our cosmic neighborhood for good. (Image by Zwicky Transient Facility)
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