Astronomers continue the search for a massive unseen planet that could reshape our understanding of the solar system.

We have discovered thousands of exoplanets in the last few decades, while the number of planets in the Solar System has remained at eight – but our discovery of more might not yet be over. A team of ...

Mike Brown is convinced that beyond Neptune, at the far reaches of our solar system, there's an unseen giant planet. "This is the 5th largest planet in our solar system, lurking out there, waiting to ...

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Astronomers believe there is a Planet Nine in the outer solar system beyond Neptune. A team led by Amos Chen from the National Tsing Hua University, is searching for Planet Nine’s heat signature. When ...

Some scientists are convinced that beyond Neptune, there's a planet they've yet to see. This so-called "Planet 9" is so far away, it would be a faint object. The stretch of sky researchers would have ...

Scientists examined infrared space surveys to narrow down candidates for Planet 9. Planet 9 would be so far from the Sun that it is just not illuminated by much sunlight. The two space surveys, ...

The solar system lost its ninth planet back when Pluto was demoted to a dwarf planet, but research might indicate that there ...

On a mountaintop in Chile's sprawling Atacama Desert, a new telescope has turned its mechanical eyes to the heavens, stargazing with unprecedented intensity. The Vera C. Rubin Observatory will take ...

When I was a kid, there were nine planets. Now we know of thousands! But that includes exoplanets, alien worlds that orbit alien suns. Only eight planets call our solar system home. Or there might ...