After 12 years, Pluto once again makes people want to call it planet

In fact, the problem is still very controversial. Do you think Pluto is worthy to be called a planet?

Before 2006, it was always considered the 9th planet of the solar system. However, by the end of the 20th century and the early years of the 21st century, scientists had found more and more objects with the same mass as Pluto.

Before 2006, Pluto was considered the 9th planet in the Solar System.

As a consequence, the International Astronomical Union (IAU) has set a new definition in which celestial bodies want to be considered planets and need to achieve certain norms. And since then, the solar system has only 8 planets, so Pluto is " downgraded" to a dwarf planet.

But despite being abandoned, Pluto was not alone when he attracted a large number of supporters and sought to reclaim "identity" for him.

As recently, Alan Stern and David Grinspoon - two astronomers in the New Horizons project, have published an article on the Washington Post, which has very valid arguments about asking for fairness for Pluto.

As known in 2006, IAU's planetary definition must ensure three criteria.

1. There must be orbit around the Sun.
2. There must be strong enough gravity to form a sphere - or near the bridge.
3. The vicinity of the planet's orbit must be cleared during the formation process.

Because Pluto's neighborhood is with so many celestial bodies - there are even bodies that carry more mass than it - so no longer called planets.

Kuiper belt - which made Pluto no longer considered a planet.

But according to Stern and Grinspoon, this definition is no longer relevant to the era. First of all, considering all three criteria, Earth may not be considered a planet anymore, because our neighborhood still has too many mysterious bodies that have not been cleared yet.

Moreover, this definition does not apply to exoplanets - planets outside the solar system. Over time, more and more exoplanet have been discovered, as well as more and more strange standards for planets that need to be added.

And finally, both thought that Pluto was fully qualified as a planet. The reason is simply because the term "planet" should be used to describe a world with certain geographical characteristics, rather than just paying attention to its orbit.

"We should use the word" planet "to describe planets with certain properties," Stern said.

"When you see a planet with features like: ice mountains, glaciers from nitrogen, a blue sky with a layer of enveloping atmosphere, we'll just call it a planet. And Pluto is done. It's like that. "

Some leading astronomers do not think Pluto is a planet.

However, not everyone agrees with them.

In 2017, Stern and Grinspoon proposed to add a criterion for planetary definition , which is "spherical bodies smaller than a star".

Unfortunately, not many scientists support this definition, because if so, our Moon could be considered a planet.

Some industry leading astronomers like Neil deGrasse do not think Pluto is the planet, with a firm affirmation at the end of 2017.

In general, Pluto is returned to being a planet or not, not knowing, only knowing that the debate around it will last for a long time in the future. Anyway, congratulate Pluto, because the " boy" was abandoned but not alone.