A massive asteroid will make a rare fly-by on Tuesday, and although it poses no danger of crashing to Earth, US scientists said this week they are eager for a closer look.

“This is not a potentially hazardous asteroid, just a good opportunity to study one,” said National Science Foundation astronomer Thomas Statler. The circular asteroid, named 2005 YU55, is about 400 metres wide and will come closer than the Moon, zipping by at a distance of 325,000 kilometres, the US space agency said. The time of the nearest fly-by is expected to be at 2328 GMT (6:28 Eastern time in the US). The encounter will be the closest by an asteroid of that size in more than 30 years, and a similar event will not happen again until 2028.

However, those who want to see it will need a telescope. The asteroid is “going to be pretty faint when it flies by,” said Scott Fisher, program director of the National Science Foundation’s Division of Astronomical Sciences.

“It will not be visible to the naked eye. You will need a telescope that has a mirror at least six inches in size to see it. To make it even more difficult to observe, it will be moving very quickly across the sky as it passes.”