If you were up early this morning you would have seen a lineup in the morning sky of Venus, Saturn and Jupiter on a line with the morning crescent moon. The lineup will be around for the next few mornings, so if there is a clear sky and you are up more than an hour before sunrise, it will be easy to spot.
Look east to the sunrise and the Moon will slide its way up past the three planets.
This morning the waning crescent moon was right next to Jupiter. (This is best viewed from North America.)
Saturn and Venus are east of Jupiter and the line they seem to all be on is the ecliptic, or Earth-sun plane. This is the plane on which the other planets in our solar system and the moon all orbit, so we view them as being on this line.