Planets | Pluto, loved by the public, would be left out of the new definition of a planet

Planetwhat is it?

Astronomers argued about the definition of a planet in the early 2000s, about a generation ago. The planet was then redefined in 2006.

It left a mess behind. The popular Pluto, for example, fell out of the group of planets. It was “downgraded” to a dwarf planet.

Now an astronomer Jean-Luc Margot His team from the University of California, Los Angeles proposes a new way to determine the planet.

In that, a planet would be defined according to the body’s mass.

Planet would be any body orbiting a star or its remnants.

However, its mass should be more than 0.005 percent of the mass of Jupiter, but not more than 13 times the mass of Jupiter. Jupiter is the largest planet in our solar system.

The lower limit has been calculated to be a figure that is approximately 10 to the power of 23 kilos. It is rooted in reality. The number corresponds to the average mass of the planets and dwarf planets in our solar system, Margot writes.

The upper limit of the mass is also natural. That mass is the point where nuclear fusion of a large body can begin. So a star is born. Another option is a brown dwarf, which is like a failed star, says the website Space.com.

Margot’s proposal leaves eight clearly defined planets in our own solar system. Man has known them all for over 170 years – Neptune was the last to be found in 1846 – most millennia.

The planet defined in a new way by the International Astronomical Union (IAU) in 2006. It is the supreme decision-making body of astronomers.

In the 2006 definition, a body that orbits the Sun is called a planet. The planet is round. In addition, the planet must control its own orbit.

One of the reasons for the new definition at the time was that new orbiting species had just been found at the edges of our solar system. One of them was named Eris. It was small, but it orbited the Sun. So was it a new planet?

Astronomers thought that with the latest equipment, more such songs would be found, and a lot. It would lead to chaos in planetology.

Reform left eight known planets in our solar system.

Pluto, loved by the public, was left behind. Pluto was a newcomer, the ninth. It was only discovered in 1930 and was downgraded to a dwarf planet in 2006.

According to the IAU, Pluto did not clear its orbit of other orbiters. It was one new definition of a planet.

Pluto spends about 20 years of its orbital period inside the orbit of Neptune. In this case, big Neptune is the ruling party of Pluto’s orbit.

The IAU’s decision annoyed not only the general public but also many astronomers. The dispute has continued to this day. In between, the probe New Horizons already managed to photograph Pluto and its moons up close. It only added to the controversy, because Pluto’s surface was peculiar, even beautiful.

If new proposal ever comes true, it still leaves Pluto out of the definition of a planet. Pluto the mass is too small to be a planet.

The same weight-based definition would neatly apply to all of the more than 5,700 known exoplanets. There are more of them all the time.

The new definition would not require the planet to measure roundness.

“The objects that dominate space are usually round,” says Margot. And they always weigh more than 10 to the power of 23 kilos.

Margot presents his proposal in August at the IAU meeting in Cape Town, South Africa. He hopes that it will be formally considered at the IAU General Assembly in 2027.

Categorization helps people communicate with each other and the public. But above all, it guides our thinking, says Margot According to New Scientist.

The group’s proposal is published in the arXiv pre-publication service. It will also be published soon by the Planetary Science Jounal.