Tag: dwarf planets

Why Is Pluto No Longer A Planet?

In 2006, Pluto was voted out of the planetary club by members of the International Astronomical Union

But in 2006, it was relegated to the status of dwarf planet by the International Astronomical Union (IAU). So why was Pluto demoted?

Where did the controversy start?

Pluto was discovered in 1930 by US astronomer Clyde Tombaugh, who was using the Lowell Observatory in Arizona.

Textbooks were swiftly updated to list this ninth member in the club. But over subsequent decades, astronomers began to wonder whether Pluto might simply be the first of a population of small, icy bodies beyond the orbit of Neptune.

This region would become known as the Kuiper Belt, but it took until 1992 for the first “resident” to be discovered.

The candidate Kuiper Belt Object (KBO) 1992 QBI was detected by David Jewitt and colleagues using the University of Hawaii’s 2.24m telescope at Mauna Kea.




How did this change things?

Confirmation of the first KBO invigorated the existing debate. And in 2000, the Hayden Planetarium in New York became a focus for controversy when it unveiled an exhibit featuring only eight planets.

The planetarium’s director Neil deGrasse Tyson would later become a vocal figure in public discussions of Pluto’s status.

But it was discoveries of Kuiper Belt Objects with masses roughly comparable to Pluto, such as Quaoar (announced in 2002), Sedna (2003) and Eris (2005), that pushed the issue to a tipping point.

Eris, in particular, appeared to be larger than Pluto – giving rise to its informal designation as the Solar System’s “tenth planet“.

The discovery of other icy objects similar in size to Pluto forced a re-think by the IAU

Prof Mike Brown of the California Institute of Technology (Caltech), who led the team that found Eris, would later style himself as the “man who killed Pluto”, while deGrasse Tyson would later jokingly quip that he had “driven the getaway car”.

The finds spurred the International Astronomical Union to set up a committee tasked with defining just what constituted a planet, with the aim of putting a final draft proposal before members at the IAU’s 2006 General Assembly in Prague.

Under a radical early plan, the number of planets would have increased from nine to 12, seeing Pluto and its moon Charon recognised as a twin planet, and Ceres and Eris granted entry to the exclusive club. But the idea met with opposition.

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Goblin, The Hidden Planet Nine, Lurking In Outskirts Of Our Solar System?

There is a growing evidence that our solar system has another Planet Nine or Planet X that is orbiting the Sun at a great distance.

Astronomer Scott S. Sheppard of the Carnegie Institution for Science in Washington and his team explained the orbital details of the planet, which they have nicknamed Goblin, while officially it is designated in 2015 as TG387.

The team took three years to figure out the orbit of the Planet, which is interesting. Their findings have been published in the Astronomical Journal.

Distanced at about 7.4 billion miles from the sun, or about 2.5 times farther away than Pluto, the planet’s most distant end of its elliptical, 40,000-year orbit, is nearly 70 times farther from the sun than Pluto.

However, TG387 remains far beyond the pull of the gravitation of Jupiter, Saturn, Uranus and Neptune, and astronomers have now discovered several bodies with such distant orbits.




In 2016, Michael Brown and Konstantin Batygin of the California Institute of Technology, originally predicted about an unseen planet, bigger than Earth yet smaller than Neptune. And it was named Planet Nine.

Ann-Marie Madigan, an astronomer at the University of Colorado, has suggested that gravity from a massive ring of small worlds early in the solar system’s history could explain the distant orbits.

“This new object does look like it’s quite good for the Planet Nine theory,” Madigan said.

Dr. Brown, who is behind Pluto’s demotion as a dwarf planet, is currently leading the search for Planet Nine. “Mostly it’s just another piece that fits in the puzzle very nicely,” said Brown.

Unseen by any earth-based telescope, TG387 is extremely lucky to have been located. We think there are thousands of these, and most of them are too distant to detect,” said Sheppard.

The discovery of the new planet may now trigger conspiracy theorists to claim that it could be the Nibiru, a rogue planet lurking outside our solar system to enter any time to cause destruction.

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