As earthlings in the US get ready to don Halloween costumes on October 31, asteroid 2015 TB145, dubbed the 'Great Pumpkin' in a reference to the holiday, will fly past the planet at a safe distance, NASA said.

The asteroid will be visible through small telescopes for astronomy enthusiasts. It will pass by the Earth at a distance of roughly 490,000 kilometres, its closest reach to Earth – about 1.3 times the distance to the moon, on 31 October at 1.05 p.m. EDT (Eastern Daylight Time).

The "Great Pumpkin", with a diameter of about 400 metres, will be moving at a speed of 126,000 kph (78,200 mph), reported EEE on Friday, 23 October.

"The trajectory of 2015 TB145 is well understood," said Paul Chodas, manager of the Center for Near Earth Object Studies at NASA's Jet Propulsion Laboratory in Pasadena, California.

In a statement, NASA said that the gravitational influence of the asteroid is too small to have any detectable effect on the moon or anything here on Earth, including tides.

Scientists from University of Hawaii's Panoramic Survey Telescope and Rapid Response System on Haleakala, Maui, who discovered asteroid 2015 TB145 on 10 October, have since calculated its trajectory. The institute is a part of the Near-Earth Object Observation Program funded by NASA.

The team will use a 34 metre DSS 13 antenna at Goldstone, California, to bounce radio waves off the asteroid. Radar echoes will in turn be collected by the National Radio Astronomy Observatory's Green Bank Telescope in Green Bank, West Virginia, and the National Astronomy and Ionosphere Centre's Arecibo Observatory in Puerto Rico.

NASA scientists hope to obtain radar images of the asteroid as fine as about 2 metres per pixel.