Surprise! We Still Haven't Found Planet Nine

A new search for Planet Nine yielded no evidence of an outer Solar System body.

Astronomers have been able to rule out an object with Planet Nine's predicted properties in a large swathe of the southern sky after six years of searching.

The objects that were found in the search might be interesting to follow up in future surveys.

The researchers wrote in their paper that there were no significant detections which were used to place limits on the millimeter-wave flux density of Planet Nine.

A list of the 10 strongest candidates from the search for possible follow-up is provided. We exclude the presence of an unknown solar system object from our survey area.

Planet Nine is a Solar System proposition. The existence of a hidden planet in the far reaches of the Solar System has been speculated about for decades, but it reached a new pitch in 2016 with the publication of a paper by Mike Brown and Konstantin Batygin of Caltech.

In their paper, Brown and Batygin suggested that small objects in the outer Solar System were being pushed into a pattern by something large. They concluded that it could be a previously unknown planet.

Astronomers discovered Neptune using telescopes, after it was predicted in a similar way. Finding Planet Nine is more difficult than finding Neptune.

If Planet Nine is out there, it could be 5 to 10 times the mass of Earth, with a distance between 400 and 800 astronomical units.

It would take between 10,000 and 20,000 years to go around the Sun.

Planet Nine is very far away, small, and cold. It probably doesn't reflect much sunlight or give off heat.

We don't know where it is in the sky. The topic is one of the most intense and interesting debates of the year, as the jury is out on whether it is real or not.

Astronomers from the Center for Computational Astrophysics at the Flatiron Institute pored over the data from the 6-meter Atacama Cosmology Telescope to try and find a hint of the planet.

The telescope is designed to detect a faint signal from the Big bang, but it is also sensitive enough to detect objects in the very far reaches of the Solar System.

The telescope scanned 87 percent of the available southern sky for distances between 300 and 2,000 units. The telescope can detect a 5 Earth mass planet between 325 to 625 astronomical units, and a 10 Earth mass planet between 425 and 775 astronomical units.

The search yielded about 3,500 tentative candidates, but none could be confirmed.

Even if they are not Planet Nine, the 10 strongest candidates for future study could still be interesting.

Previous searches for Planet Nine yielded distant Solar System rocks, as well as previously unknown moons.

The results only covered a portion of the sky and possibilities. There is still a lot of space to be covered, and there are regions in the telescope&s path that it wouldn't be able to see Planet Nine. The existence of the hypothetical object can be ruled out by the non-detection.

The researchers said that future instruments should be able to substantially widen the parameters of the search for Planet Nine, raising the possibility of detection.

The paper was published in a journal.