REVELLERS gathering for tonight's New Year's Eve fireworks may spot one extra sparkler in the sky. If the weather behaves, the international space station should be visible to thousands of people celebrating around Sydney Harbour.

The station is expected to appear in the south-western sky about 9.50pm. Two minutes later it will be almost directly overhead as it heads north-east.

Nick Lomb, the astronomer at Sydney Observatory, said yesterday that even through the glare of the city's light pollution, the space station should be "easily visible" when it is overhead, appearing as a bright star moving across the sky. It will vanish again at 9.53pm as it passes into the Earth's shadow and heads out over the Pacific Ocean.

One new year celebration every 12 months may be enough for most people, yet the station, travelling at almost eight kilometres a second, circles the world nearly 16 times a day.

As a result its crew of three - the Americans Mike Finke and Sandra Magnus, and Russia's Yuri Lonchakov - will be able to welcome 2009 about every hour and a half over the next day.

Putting the station in the sky has cost far more than all the pyrotechnic displays Sydney has ever staged put together. Its price tag has been estimated at more than $US100 billion ($145 billion).