Uranus was the first planet discovered with a telescope, in 1781.
Why it is true
Mercury, Venus, Mars, Jupiter and Saturn are visible to the naked eye and had been known since ancient times. The astronomer William Herschel, in England, first thought Uranus was a comet and wanted to call it 'George's Star' after King George III.
Source: NASA Science
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Related facts
All other planets of the solar system fit in the space between Earth and Moon.
Uranus rotates on its side, likely due to a massive collision.
There are planets that orbit two stars at the same time.
Neptune was discovered in 1846 thanks to mathematical calculations, before anyone saw it through a telescope.
