Selection centres are used by graduate employers who need to assess a large group of potential graduate recruits. Instead of interviewing each candidate individually, a selection centre allows an employer to see groups of candidates taking part in tasks and role-plays. In theory, this makes selection centres a fairer method of recruitment than an interview.
Over very long time periods (thousands of years) the direction of Earth's axis slowly changes due to precession. The Earth rotates around once in 24 hours-that's a rate of 1000 miles per hour!. The time it takes for the Earth to rotate completely around once is what we call a day. It's Earth's rotation that gives us night and day. The combined effect of the Earth's tilt and its orbital motion result in the seasons.
All the planets in the solar system spin on their axes (so does the Sun!) and so they have day and night cycles. There are differences, however, in the length of day and night. Some planets rotate faster than Earth and some rotate slower. Mars has a day/night cycle similar to Earth. Mars rotates on its axis once every 24.6 hours. Venus turns once on its axis every 243 Earth days (which is a little longer than it takes for Venus to go around the Sun!).