The US space shuttle Endeavourjoins with the International Space Station (ISS) over Ireland tonight.
The €100 billion ISS will be flying over Irish skies for the next fortnight.
The shuttle is undertaking a 14-day mission, that includes three spacewalks to complete work on the Space Station's 80-metre solar panels and repairs to a gyroscope.
These extensions will make the Space Station the largest and brightest object ever to fly in Earth-orbit.
An Astronomy Ireland spokesman said: "Currently, the 200-tonne space station is 73 metres wide and has since its launch in 2000 travelled over two billion kilometres in 48 thousand orbits. For a couple of minutes every night it outshines every star and planet in the night sky."
The ISS is the most expensive piece of space-hardware ever, representing a collaborative effort of nearly 20 countries, including Ireland.
To get exact times of the fly-overs, Astronomy Ireland has set up a special newsline on 1550-111442.
PA
