6.13 - Understand, in relation to astronomical observations, the terms:
b) culmination

6.16 - Understand the apparent motion of circumpolar stars, including upper transit (culmination) and lower transit

A star is said to culminate when it is in the highest point in the sky.

Let’s bring back a term used in astronomy that has two meanings - Transit. This is done to confuse you.

Over the course of a year a star will reach it’s highest point (its upper transit) and it’s lowest point (its lower transit).

So for example lets look at three starts from London at latitude 51 degrees north.

  • Star 1 reaches upper transit in March and lower transit in September. It is visible above the horizon all year long. It is a circumpolar star.
  • Star 2 reaches visible upper transit in April and lower transit in October. It is only visible from February to June. Its lower transit is below the horizon. It is a seasonal star.
  • Star 3 reaches upper transit in May and lower transit in November. It is not visible at any time of the year. The good people of London have not seen it.



There are two similar meanings of transit: