Here is our incredible solar system which has fascinated humans for all time:

In our solar system, some planets ORBIT nearer the Sun than Earth, and some planets ORBIT further away from the Sun than Earth. 

The time it takes for a planet to travel once around the Sun is called a YEAR. Planets further away from the Sun have longer years because it takes longer to travel the distance.  Have a think about that.

Planets spin at different speeds to the Earth, so their days are not 24 hours. (Venus has a day which lasts 243 Earth days!).  Have a longer think about that!

Does that mean that on Venus your birthday is always tomorrow?!  Let's have a look at our solar system....