A comet not expected to return for 110,000 years is visible above New Zealand - even through city lights.

The Panstarrs comet was travelling across the night’s sky this week and on Tuesday was about 163 million kilometres away.

Each night this week it was visible near the horizon of the western sky. It can be seen with the naked eye, but is better sighted with binoculars.

Dusk towards early evening was the best time to see it.

Wellington’s Carter Observatory astronomer John Field said the comet was right now between the Earth and the Sun, heading towards the Sun.

''It looks like a little bright star with a hazy tail,'' Field said.

The comet, officially known as Comet C/2011 L4, was discovered in June 2011 by the Panoramic Survey Telescope and Rapid Response System, or Panstarrs, in Hawaii.

Comet Panstarrs is believed to be a first-time visitor to Earth after being gravitationally bumped out from the Oort Cloud, a repository of small icy bodies located beyond Pluto in the solar system's back yard.

Comets, which are comprised of minerals, rocks and ice, are believed to be remnants from the formation of the solar system some 4.5 billion years ago.

As a comet approaches the Sun, some of its ice vaporises, creating an envelope of gas and dust, called a coma, around its body. The heating also generates two tails, each of which can be more than 1.6 million km long.

One tail is comprised of dust and the other is made of molecules ionized by sunlight.

Comet Panstarrs currently is inside the orbit of Mercury and brightening as it heads toward the Sun.

ANOTHER COMET COMING

Panstarrs may just be the warm-up act for another celestial visitor due to arrive in November.

If it is not destroyed by the Sun, comet Ison has the potential to be as bright as a full moon, possibly even visible in daylight.

Ison, which was discovered last year by two amateur astronomers in Russia, was expected to pass as close as 1.1 million kilometres from the surface of the Sun - about four times closer than Comet Panstarrs will pass during its closest approach to the Sun on Sunday.

- Fairfax NZ with AP

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