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Dark worlds: Seven new rogue planets discovered by Euclid

The Euclid space telescope has made a remarkable discovery, identifying seven new rogue planets, shedding light on these dark, starless worlds that drift freely through the universe. 

Trillions of rogue planets 

Unlike planets bound to stars, rogue planets do not experience days or years, existing in perpetual night. Despite their isolation, scientists believe these planets might host life and estimate their number in the trillions within the Milky Way.

The European Space Agency recently released the first scientific results from the Euclid mission, which launched in July. Among these findings were seven new free-floating gas giants, each at least four times the mass of Jupiter.

Finding a needle in a haystack 

The planets are located in the Orion Nebula, the nearest star-forming region to Earth, about 1,500 light-years away. The Euclid telescope also confirmed the existence of dozens of previously detected rogue planets. According to Spanish astronomer Eduardo Martin, this is likely just the “tip of the iceberg.”

Because rogue planets do not reflect the light of a star, detecting them is challenging, akin to “finding a needle in a haystack,” as Martin put it. 

Younger planets, such as those discovered by Euclid, are slightly easier to spot due to their higher temperatures. Some research suggests there may be around 20 rogue planets for every star, potentially translating to trillions of such planets in our galaxy alone.

Fascinating rogue planets 

Gavin Coleman, an astronomer at Queen Mary University of London, who was not involved in the Euclid research, highlighted the fascination with these rogue planets. 

“We’ve all grown up with the sun in the sky, and so to think of a planet just drifting through space with no star on its horizon is fascinating.”

Interestingly, not all rogue planets wander alone. Some, like the four confirmed by Euclid, are binary systems, where two planets orbit each other.

Potential for life

The potential habitability of rogue planets has significant implications in the search for extraterrestrial life. “Some of our closest neighbors are likely rogue planets,” Martin said. 

These planets are believed to be cold, with any life-supporting energy coming from within rather than from a star. On Earth, geothermal vents allow life to thrive in darkness, suggesting a similar possibility for rogue planets. However, Coleman noted that this extreme isolation would likely only support bacterial and microbial life.

Worlds without a nearby star

While rogue planets traverse a lonely path, they avoid some hazards associated with being near a star. For example, when the sun becomes a red giant, it will expand and potentially destroy the Earth. Rogue planets do not face this risk. 

“These things will last forever. If you don’t mind the cold temperatures you could survive on these planets for eternity,” said Conselice.

Formation of rogue planets 

Euclid’s findings also provide insights into the formation of rogue planets. Some may have formed in the outer regions of solar systems before being ejected, while others might be a natural byproduct of the star-formation process. 

This connection between stars and planets suggests a close relationship in their formation, although there are no firm answers yet.

This groundbreaking discovery by the Euclid space telescope offers a glimpse into the dark, lonely worlds of rogue planets, enhancing our understanding of the universe and opening new avenues for the study of planetary formation and the potential for life beyond Earth.

More about rogue planets 

The existence of rogue planets came into consideration as astronomers discovered more about planetary formation and dynamics.

As previously mentioned, these planets may have formed around a star and were later ejected from their original solar systems due to gravitational disturbances, often caused by close encounters with other planets or stars. 

Alternatively, some theories suggest that rogue planets could have formed in isolation within a star-forming cloud but failed to accrete enough mass to ignite into stars themselves.

Rogue planets are difficult to detect because they don’t emit light like stars and don’t reflect light from a host star. 

However, techniques such as gravitational microlensing – where the gravity of the rogue planet bends the light from a distant star behind it – have allowed astronomers to spot these elusive objects. 


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