Our solar system is quite a busy place. There are millions of moving objects – from planets and moons to comets and asteroids. And every year we discover more and more objects (usually small asteroids or fast-moving comets) that inhabit the solar system.
Astronomers had found the eight main planets in 1846. But that doesn’t stop us from looking for others. Over the past 100 years we have found smaller distant bodies that we call dwarf planets, what we now classify as Pluto.
The discovery of some of these dwarf planets has given us reason to believe that something else might be lurking on the outskirts of the solar system.
Could there be a ninth planet?
There’s a good reason why astronomers spend hundreds of hours trying to locate a ninth planeta.k.a ” planet nineor “Planet X.” And that’s because the solar system as we know it doesn’t really make sense without it.
Every object in our solar system orbits the Sun. Some move quickly and others slowly, but all move according to the laws of gravity. Everything with mass has gravity, including you and me. The heavier something is, the more gravity it has.
A planet’s gravity is so great that it impacts how things move around it. This is what we call its “gravitational pull”. Earth’s gravitational pull is what keeps everything grounded.
Additionally, our Sun has the greatest gravitational pull of any object in the Solar System, and this is essentially why the planets revolve around it.
It is through our understanding of gravitational pull that we get our biggest clue to a possible planet nine.
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Unexpected behaviors
When we look at very distant objects, such as dwarf planets beyond Pluto, we find that their orbits are a bit unexpected. They move in very large elliptical (oval-shaped) orbits, are clustered together, and exist on a slope relative to the rest of the solar system.
When astronomers use a computer to model what gravitational forces are needed for these objects to move like this, they find that a planet at least ten times the mass of Earth would have been needed to cause this.
This is super exciting stuff! But then the question is: where is this planet?
The problem we have now is trying to confirm whether these predictions and models are correct. The only way to do that is to find Planet Nine, which is definitely easier said than done.
The hunt continues
Scientists around the world have been searching for visible evidence of Planet Nine for many years now.
Based on computer models, we believe Planet Nine is at least 20 times farther from the Sun than Neptune. We try to detect it by looking for sunlight that it may reflect – just like how the moon shines from reflected sunlight at night.
However, since Planet Nine sits so far from the Sun, we expect it to be very faint and difficult to spot, even for the best telescopes on Earth. Also, we can’t just look for it at any time of the year.
We only have small windows of nights where the conditions must be there. Concretely, it is necessary to wait for a night without Moon, and whose place of observation faces the right part of the sky.
But don’t lose hope just yet. Over the next decade, new telescopes will be built and new surveys of the sky will begin. They might just give us the opportunity to prove or disprove the existence of Planet Nine.
Sarah Webbpostdoctoral researcher, Center for Astrophysics and Intensive Computing, Swinburne University of Technology
This article is republished from The conversation under Creative Commons license. Read it original article.