Date:
September 7, 2018

Source:
University of Central Florida

Summary:
The reason Pluto lost its planet status is not valid, according to new research.

 

Should Pluto be reclassified a planet again? UCF scientist Philip Metzger says yes based on his research.
Credit: NASA

 

 

The reason Pluto lost its planet status is not valid, according to new research from the University of Central Florida in Orlando.

In 2006, the International Astronomical Union, a global group of astronomy experts, established a definition of a planet that required it to “clear” its orbit, or in other words, be the largest gravitational force in its orbit.

Since Neptune’s gravity influences its neighboring planet Pluto, and Pluto shares its orbit with frozen gases and objects in the Kuiper belt, that meant Pluto was out of planet status. However, in a new study published online Wednesday in the journal Icarus, UCF planetary scientist Philip Metzger, who is with the university’s Florida Space Institute, reported that this standard for classifying planets is not supported in the research literature.

Metzger, who is lead author on the study, reviewed scientific literature from the past 200 years and found only one publication — from 1802 — that used the clearing-orbit requirement to classify planets, and it was based on since-disproven reasoning.

He said moons such as Saturn’s Titan and Jupiter’s Europa have been routinely called planets by planetary scientists since the time of Galileo.

“The IAU definition would say that the fundamental object of planetary science, the planet, is supposed to be a defined on the basis of a concept that nobody uses in their research,” Metzger said. “And it would leave out the second-most complex, interesting planet in our solar system.” “We now have a list of well over 100 recent examples of planetary scientists using the word planet in a way that violates the IAU definition, but they are doing it because it’s functionally useful,” he said. “It’s a sloppy definition,” Metzger said of the IAU’s definition. “They didn’t say what they meant by clearing their orbit. If you take that literally, then there are no planets, because no planet clears its orbit.”

The planetary scientist said that the literature review showed that the real division between planets and other celestial bodies, such as asteroids, occurred in the early 1950s when Gerard Kuiper published a paper that made the distinction based on how they were formed.

However, even this reason is no longer considered a factor that determines if a celestial body is a planet, Metzger said.

Study co-author Kirby Runyon, with Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, said the IAU’s definition was erroneous since the literature review showed that clearing orbit is not a standard that is used for distinguishing asteroids from planets, as the IAU claimed when crafting the 2006 definition of planets.

“We showed that this is a false historical claim,” Runyon said. “It is therefore fallacious to apply the same reasoning to Pluto,” he said. Metzger said that the definition of a planet should be based on its intrinsic properties, rather than ones that can change, such as the dynamics of a planet’s orbit. “Dynamics are not constant, they are constantly changing,” Metzger said. “So, they are not the fundamental description of a body, they are just the occupation of a body at a current era.”

Instead, Metzger recommends classifying a planet based on if it is large enough that its gravity allows it to become spherical in shape.

“And that’s not just an arbitrary definition, Metzger said. “It turns out this is an important milestone in the evolution of a planetary body, because apparently when it happens, it initiates active geology in the body.”

Pluto, for instance, has an underground ocean, a multilayer atmosphere, organic compounds, evidence of ancient lakes and multiple moons, he said.

“It’s more dynamic and alive than Mars,” Metzger said. “The only planet that has more complex geology is the Earth.”

Story Source:

Materials provided by University of Central Florida. Original written by Robert H. Wells. Note: Content may be edited for style and length.


Journal Reference:

  1. Philip T. Metzger, Mark V. Sykes, Alan Stern, Kirby Runyon. The Reclassification of Asteroids from Planets to Non-PlanetsIcarus, 2018; DOI: 10.1016/j.icarus.2018.08.026

 

Source: University of Central Florida. “Pluto should be reclassified as a planet, experts say.” ScienceDaily. ScienceDaily, 7 September 2018. <www.sciencedaily.com/releases/2018/09/180907110422.htm>.

Date:
September 12, 2018

Source:
New York University

Summary:
A team of scientists has uncovered the neural processes mice use to ignore their own footsteps, a discovery that offers new insights into how we learn to speak and play music.

 

We are often unaware of the sound of our own footsteps. How is that?
Credit: © Radnatt / Fotolia

 

 

A team of scientists has uncovered the neural processes mice use to ignore their own footsteps, a discovery that offers new insights into how we learn to speak and play music.

The research is reported in the journal Nature.

“The ability to ignore one’s own footsteps requires the brain to store and recall memories and to make some pretty stellar computations,” explains David Schneider, an assistant professor at New York University’s Center for Neural Science and one of the paper’s lead authors. “These are the building blocks for other, more important sound-generating behaviors, like recognizing the sounds you make when learning how to speak or to play a musical instrument.”

The research, conducted at Duke University’s School of Medicine, centered on an intuition — that we are usually unaware of the sound of our own footsteps — as a vehicle for understanding larger neural phenomena: how this behavior reveals the ability to monitor, recognize, and remember the sound of one’s own movements in relation to those of their larger environments.

“The capacity to anticipate and discriminate these movement-related sounds from environmental sounds is critical to normal hearing,” Schneider explains. “But how the brain learns to anticipate the sounds resulting from our movements remains largely unknown.”

To explore this, Schneider and his colleagues, Janani Sundararajan and Richard Mooney at Duke’s School of Medicine, designed an “acoustic virtual reality system” for the mice. Here, the scientists controlled the sounds the mice made walking on a treadmill while monitoring the animals’ neural activity, allowing them to identify the neural circuit mechanisms that learn to suppress movement-related sounds.

Overall, they found a flexibility in neural function — the mice developed an adjustable “sensory filter” that allowed them to ignore the sounds of their own footsteps. In turn, this allowed them to better detect other sounds arising from their surroundings.

“For mice, this is really important,” said Schneider. “They are prey animals, so they really need to be able to listen for a cat creeping up on them, even when they’re walking and making noise.”

Being able to ignore the sounds of one’s own movements is likely important for humans as well. But the ability to anticipate the sounds of our actions is also important for more complex human behaviors such as speaking or playing music.

“When we learn to speak or to play music, we predict what sounds we’re going to hear — such as when we prepare to strike keys on a piano — and we compare this to what we actually hear,” explains Schneider. “We use mismatches between expectation and experience to change how we play — and we get better over time because our brain is trying to minimize these errors.”

Being unable to make predictions like this is also thought to be involved in a spectrum of afflictions.

“Overactive prediction circuits in the brain are thought to lead to the voice-like hallucinations associated with schizophrenia while an inability to learn the consequences of one’s actions could lead to debilitating social paralysis, as in autism,” explains Schneider. “By figuring out how the brain normally makes predictions about self-generated sounds, we open the opportunity for understanding a fascinating ability — predicting the future — and for deepening our understanding of how the brain breaks during disease.”

Story Source:

Materials provided by New York UniversityNote: Content may be edited for style and length.


Journal Reference:

  1. David M. Schneider, Janani Sundararajan, Richard Mooney. A cortical filter that learns to suppress the acoustic consequences of movementNature, 2018; DOI: 10.1038/s41586-018-0520-5

 

Source: New York University. “We may hear others’ footsteps, but how do we ignore our own?.” ScienceDaily. ScienceDaily, 12 September 2018. <www.sciencedaily.com/releases/2018/09/180912133507.htm>.