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Is Pluto a planet or not? Yes, it is and so are over 100 Celestial Bodies

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In this image of Pluto taken by NASA’s New Horizons spacecraft, different colors represent different compositions of surface ices, revealing a surprisingly active body. (Image: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute) VOA
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NEW YORK, March 18, 2017: Is Pluto a planet or not? Giving this debate a fresh angle, Johns Hopkins University scientist Kirby Runyon wants to make one thing clear: Regardless of what people say, Pluto is a planet.

So, Runyon says, is Europa — commonly known as a moon of Jupiter — and so is the Earth’s Moon and so are more than 100 other celestial bodies in our solar system that are denied this status under the prevailing definition of “planet”.

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The definition approved by the International Astronomical Union in 2006 demoted Pluto to “non-planet,” thus dropping the consensus number of planets in our solar system from nine to eight.

“The change – a subject of much scientific debate at the time and since – made no sense,” said Runyon, lead author of a paper set to be presented next week at a scientific conference in Texas.

Icy, rocky Pluto had been the smallest of the nine planets; its diameter under three-quarters that of the moon and nearly a fifth of Earth.

Still, says Runyon, Pluto “has everything going on on its surface that you associate with a planet. … There’s nothing non-planet about it”.

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Runyon led a group of six authors from five institutions in drafting a proposed new definition of “planet,” and a justification for that definition.

All the authors are science team members on the New Horizons mission to Pluto, operated for Nasa by the John Hopkins University Applied Physics Laboratory.

In the summer of 2015, the New Horizons spacecraft became the first to fly by Pluto, some 4.67 billion miles from Earth, passing within 8,000 miles and sending back the first close-up images ever made of Pluto.

Runyon and his co-authors argue for a definition of “planet” that focuses on the intrinsic qualities of the body itself, rather than external factors such as its orbit or other objects around it.

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They define a planet as “a sub-stellar mass body that has never undergone nuclear fusion” and that has enough gravitational heft to maintain a roughly round shape.

This definition differs from the IAU definition in that it makes no reference to the celestial body’s surroundings.

That portion of IAU’s 2006 formula – which required that a planet and its satellitesmove alone through their orbit – excluded Pluto.

Otherwise, Pluto fit the IAU definition: It orbits the Sun and it is massive enough that the forces of gravity have made it round.

The proposed new geophysical definition omits stars, black holes, asteroids and meteorites, but includes much of everything else in our solar system.

It would expand the number of planets from eight to approximately 110. (IANS)

 

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Habitability Of Surrounding Planets Affected By Super Flares Of Red Dwarfs: NASA

Red dwarfs -- especially young red dwarfs -- are active stars, producing flares blast out energy

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NASA, tissue
Wintertime ice growth in Arctic sea slows long-term decline: NASA. Flcikr

Using NASA’s Hubble Space Telescope, astronomers have found that violent outbursts, or superflares, from red dwarf stars could affect the habitability of any planets orbiting it.

Young low-mass stars flare much more frequently and more energetically than old stars and middle-age stars like our Sun, the findings of the study published in the Astrophysical Journal showed.

The findings are based on observations of the flare frequency of 12 red dwarfs.

Hubble is observing such stars through a large programme called HAZMAT — Habitable Zones and M dwarf Activity across Time.

“M dwarf” is the astronomical term for a red dwarf star — the smallest, most abundant and longest-living type of star in our galaxy.

Hubble Telescope. red dwarf
Hubble Telescope. Flickr

The HAZMAT programme is an ultraviolet survey of red dwarfs at three different ages — young, intermediate, and old.

“The goal of the HAZMAT programme is to help understand the habitability of planets around low-mass stars,” explained the programme’s principal investigator, Evgenya Shkolnik from Arizona State University.

“These low-mass stars are critically important in understanding planetary atmospheres,” Shkolnik added.

Stellar flares from red dwarfs are particularly bright in ultraviolet wavelengths, compared with Sun-like stars.

Red dwarf  planet
Artist’s view of planets transiting red dwarf star in TRAPPIST-1 system. Flickr

Hubble’s ultraviolet sensitivity makes the telescope very valuable for observing these flares.

The flares are believed to be powered by intense magnetic fields that get tangled by the roiling motions of the stellar atmosphere.

When the tangling gets too intense, the fields break and reconnect, unleashing tremendous amounts of energy.

The team found that the flares from the youngest red dwarfs they surveyed — just about 40 million years old — are 100 to 1,000 times more energetic than when the stars are older.

This younger age is when terrestrial planets are forming around their stars.

Red dwarf
This illustration shows a red dwarf star orbited by a hypothetical exoplanet. NASA

About three-quarters of the stars in our Milky Way galaxy are red dwarfs. Most of the galaxy’s “habitable-zone” planets — planets orbiting their stars at a distance where temperatures are moderate enough for liquid water to exist on their surface — orbit red dwarfs.

In fact, the nearest star to our Sun, a red dwarf named Proxima Centauri, has an Earth-size planet in its habitable zone.

Also Read: NASA Plans For Science Payloads For Delivery To Moon

However, red dwarfs — especially young red dwarfs — are active stars, producing flares that could blast out so much energy that it disrupts and possibly strips off the atmospheres of these fledgling planets. (IANS)