![Rocky planet covered with active volcanoes and glowing lava flows.](https://earthsky.org/upl/2023/05/LP79118d-exoplanet-volcanoes-artist-illustration-May-17-2023.jpg)
On Monday, July 22, 2024, EarthSky’s Deborah Byrd will be speaking LIVE with Jean-Luc Margot, a Belgian-born astronomer and professor at UCLA. Margot and his team have just published a new paper outlining why we need a new definition of “planet.” They will be presenting their ideas at the IAU General Assembly (a global gathering of astronomers) beginning August 6 in Cape Town, South Africa.
When Pluto was demoted from planet status in 2006, it was because the International Astronomical Union's definition of a planet had changed. The change created quite a stir. But since the mid-1990s, scientists have discovered more than 5,000 exoplanets, or worlds orbiting distant stars. Meanwhile, the IAU definition applies only to planets within our solar system. The newly proposed definition of a planet is less heliocentric.
The new definition specifies that “planets” can orbit one or more stars, brown dwarfs or stellar remnants.
It sets mass limits that its creators say should apply to all planets.
But will it return Pluto to its full planetary status?
Jean-Luc Margot and his team published a new study in Journal of planetary science Last week (July 17, 2024) they outlined their reasons for the suggested change in definition to “planet.” Find their study here: Quantitative criteria for defining planets.
![What is a planet? A young man with glasses and a black UCLA t-shirt.](https://earthsky.org/upl/2024/07/jean-luc-margot_2022-03-08-181045_vwoa.jpg.webp)
Bottom line: When the International Astronomical Union created a definition of “planet” in 2006, Pluto lost its status as a planet. Now astronomers are proposing a new definition of “planet.”
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