There used to be 9 planets and more than 170 moons in our solar system.
The 9 planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.
But in August 2006, the International Astronomical Union decided to re-classify Pluto as a “dwarf planet”, and not in the same category as the 8 planets.
So now there are 8 planets in the solar system.
Each planet goes around the Sun on its own path called orbit.
Anyway we cannot see the paths because they are invisible.
Earth takes about 365 days to orbit the Sun.
This is called one Earth year.
And each moons moves around its planet in its own orbit.
The size of the planet from the smallest to the biggest:
On April 12, 1961, Yuri Alekseyevich Gagarin became the first person who went to space.
People travel to space in a spacecraft or spaceship.