Rights: © Copyright 2009. University of Waikato. All Rights Reserved. Published 1 April 2009 Download

Professor Denis Sullivan, from Victoria University of Wellington, explains how microlensing can be used to detect planets in orbit around stars other than our Sun.


The Microlensing Method is probably the most obscure method but that’s now been a method that’s used to detect something like ten planets so far. The problem is it’s only one off. You know, it’s an event that happens and then you’ll probably never see it again.

But, basically, you have a star away way, way in the distance and we are looking at that star, and then if an object comes close enough in the line of sight, then the light is magnified because light forms a curved path in an ever so small amount due to the gravitational field, so that’s why it’s called Gravitational Microlensing. So, to see these effects what you need to do is monitor huge numbers of stars with electronic cameras because the probability of stars lining up like that is very, very small. So if you monitor huge numbers of stars and you will see some of them increase and decrease over days to weeks in this characteristic way then you know that you’ve got a microlensing event.