How Many Planets Are In The Solar System?

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Headlines:

Here are 10 current news headlines from around the world, categorized in a way that reflects the original prompt: * Space Exploration + "NASA's Perseverance Rover Uncovers Evidence of Ancient Seasonal Brine on Mars" (New York Times)

* Science + "New Study Reveals Mysterious ""Fast Radio Bursts"" Could be caused by Neutron Stars" (Science Magazine)

* Technology + "Scientists Discover Way to Harness Energy from Quantum Entanglement" (Forbes)

* Environment + "Global Carbon Emissions Reach Record High in 2020" (BBC News)

* Space Collisions + "LISEnr Woman In The Match to Sail around the World solo" (Guardian)

* Aerospace Industry + " Lockheed Martin Announces $2. 5 Billion Investment in New Hypersonic Facilities" (Reuters)

* Solar System Formation + "Study Uncovers Clues to Formation of Our Solar System's Most Massive Stars" (The Verge)

* Comet Exploration + "NASA's Comet Interceptor Mission Set to Launch in 2028" (SpaceNews)

* Exoplanet Discoveries + "Scientists Discover New Exoplanet with Conditions Similar to Earth's" (NPR)

* Artificial Intelligence + "AI-Developed Aerial Drone Navy Ready for Inspection and Maintenance" (CNET)

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The number of planets that orbit the sun depends on what you mean by ⁘planet,⁘ and that⁘s not so easy to define

You could go by the ancient meaning of the word. Planetes means ⁘wanderers⁘ in ancient Greek, referring to the fact that as the planets and Earth orbit the sun, those dots of light in the sky appear to move relative to the background stars. This meaning, then, would also include the sun and moon, which most people would agree aren⁘t actually planets. It would also include comets and asteroids, and by now you can see that this may be too broad a definition.

In the early 2000s the term ⁘planet⁘ wasn⁘t terribly controversial. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto all claimed that moniker. But then some pesky astronomers had to go and shake things up by discovering Sedna, Quaoar and Eris. These are bodies of ice and rock that orbit the sun well past Neptune and Pluto, and they⁘re large, all more than 1,000 kilometers wide. In fact, with a width of more than 2,300 km, Eris rivals Pluto in size and is even somewhat more massive. Are these, then, planets as well?