Mars is paying us its closest visit for the next 17 years, making the red planet appear bigger and brighter than usual.

While Earth and Mars follow elliptical or oval-shaped orbits around the Sun, the fact our planet is closer than Mars means Earth speeds along its orbit faster.

This meant Earth effectively took two trips around the Sun in the same time it took for Mars to make just a single circuit.

When Earth lined up directly between Mars and the Sun, this put Mars in "opposition" – an occurrence that took place around every two years, and next occurring on July 27.

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But astronomers say this year's opposition will be all the more special.

Mars perihelion was the point when the planet was closest to the Sun in its orbit.

When this occurred within a few weeks of opposition, a "perihelic opposition" resulted, and Mars appeared even bigger and brighter.

Such events only happened around every 17 years – and some brought us closer than others.

The 2003 opposition was especially significant, being the closest opposition in the last 60,000 years.

While this year's conditions wouldn't be quite as extraordinary, Mars would still only appear 4 per cent smaller than that spectacle.

It was likely the next time the two planets are at perihelic opposition, in 2035, humans will have walked upon the surface of Mars.

The celestial event wasn't confined to the end of the month, and star-gazers should have several weeks to get an up-close view of Mars.

Telescope viewing would yield the best results, but the unaided eye could still spot Mars looking like the brightest, reddest "star" in the night sky.

Auckland's Stardome observatory was celebrating with a series of "Mad About Mars" events running this month and August.

Its historic Zeiss telescope – one of the largest telescopes in New Zealand open for regular public viewing – was open for extended hours and discounted rates throughout July and August.