A unique phenomenon will be visible in the night skies for the first time in 20 years this month.

Skywatchers will be able to see five planets lining up side-by-side in the in a “parade of the planets”.

Experts have described the prospect as “rare” with three planets at once being a more common occurrence.

The parade will see Mercury, Venus, Mars, Jupiter and Saturn aligning themselves.

According to Sky & Telescope the phenomenon was visible on June 3 and June 4, but only for around half an hour before Mercury was lost in the Sun’s glare.

However, the five planets will be visible again on June 24, with viewing at its optimal peak, The Express reports.

Conditions should be good enough that the planets are visible to the naked eye, though a pair of binoculars is always worth having to hand so that you can definitely take in the rare sights.

Even if it is cloudy the planets should still be visible in the preceding days.

On June 24, the best viewing will be available for an hour slightly before sunrise, with Mercury becoming visible on the horizon shortly before the glare from the sun makes it invisible.

Experts have said the best time to see the alignment on June 24 is 45 minutes before sunrise, where it should be visible on the eastern horizon.

Diana Hannikainen, Observing Editor at Sky & Telescope, told CBS the sky on the morning of June 24 "will present a delightful sight" for observers.

The last time the five naked-eye planets were strung across the horizon in sequence was in December 2004.