Is Pluto a planet?
Pluto is officially no longer classed as a planet, and here's why. The International Astronomical Union defined three rules in 2005 that a celestial body (an object observable within space) must follow to be classed as a planet:
1. The planet must orbit the sun.
2. The planet must be large enough that its gravity can smooth it into a nice spherical shape.
3. It must have cleared up the surrounding objects around it.
Pluto fails number three as it simply isn't massive enough to pull the surrounding objects into it's orbit. This is really hard for Pluto as it lives in the Kuiper Belt, a belt of other large rocky objects.
Fortunately for Pluto it matches the first two rules, so it can be classed as a dwarf planet instead!
CG
Related Physics A Level answers
All answers ▸If two cars are moving, labelled car A and car B. Car A moves at 15 m/s and B at 10 m/s but car B also accelerated at 2 m/s/s. If the two both travel for ten seconds, which car will travel further?
Why is the refractive index of water bigger than that of air?
An electron of mass 9.11x10^(-31) is fired from an electron gun at 7x10^6 m/s. What size object will the electron need to interact with in order to diffract?
find and symplify the following. Integrate ( 2x^5 - 1/(4x^3)- 5 )dx