Rare close-up view of asteroid over NZ skies

Space Situational Awareness - Near Earth Objects Asteroid approaching Earth.

Kiwi astronomers got a rare chance to witness an asteroid travel across the sky above New Zealand this morning.

The whale-sized asteroid, which was only discovered around a week ago, was nicknamed Pitbull because of its small size but potentially threatening path, as it flew within 40,000km of Earth.

Officially named 2014 RC, the celestial object was closer than weather satellites, Stardome Observatory astronomer Grant Christie said.

When it was first discovered, on August 29, it was initially thought it would directly hit Earth, he said.

Stardome staff tracked the asteroid from around 7pm on Sunday to after 3am on Monday, making observations and snapping images.

"It's interesting because these are things that inhabit our solar system that we know very little about really -- we don't know how many there are, and, okay they're not going to be globally devastating if they hit, but they could certainly make a big mess of a town or a city if they actually took a direct hit," Mr Christie said.

However, he added "there's a pretty low chance that would happen".

Most asteroids that size would probably go undetected, Mr Christie said.

"Objects that are only the size of a house, that's not very big from 40,000km, at closest."

Asteroids and comets are understood to be remnants from a giant cloud of gas and dust that condensed to create the sun, planets, and moons about 4.5 billion years ago.