IT'S been an exciting week for sky gazers, with a supermoon followed by a sun halo.

People in South Wales - including in Newport, Monmouthshire, and Caerphilly - have been sharing photos of the sun today surrounded by a big ring which is a rare optical phenomena known as a 'sun halo'.

According to Met Office: "Haloes require ice crystals to form - either from high cirrus cloud of free falling crystals.

South Wales Argus: The sun halo was visible in Monmouthshire (Picture: Camera Club member Catherine Mayo)

The sun halo was visible in Monmouthshire. Picture: South Wales Argus Camera Club member Catherine Mayo

South Wales Argus: The sun halo was spotted in Newport (Picture: Camera Club member Paul Morris)

The sun halo was spotted in Newport. Picture: South Wales Argus Camera Club member Paul Morris

"Typically sunlight or moonlight is reflected by ice crystals producing a white halo. However, if the light rays strike the light at a particular angle, some light may be refracted. In such situations the halo will have a faint colouration."

In simple terms, a sun halo is formed due to light reflecting from ice crystals high up in the atmosphere.

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The most common type are 22-degree Haloes. This is because the majority of ice crystals are hexagonal, or six-sided, and the most common angle of refraction through such a crystal is about 22 degrees.

But, in some cases there are different structures and angles, resulting in haloes which vary in size; in some cases only part of the halo forms.

South Wales Argus: The sun halo (Picture: Camera Club member Donna Evans)

The sun halo. Picture: South Wales Argus Camera Club member Donna Evans

South Wales Argus: The sun halo over Oakdale (Picture: Camera Club member Karen Morgan)

The sun halo over Oakdale. Picture: South Wales Argus Camera Club member Karen Morgan 

This follows on from a supermoon which occurred on Wednesday night. Due to the orbit of Earth and the moon the distance between them varies.

The moment the moon is closest to Earth - known as 'lunar perigree' - sometimes coincides with a full or new moon, and produces a 'supermoon' which appears bigger and brighter than usual.

This 'flower' supermoon (named this due to it coinciding with the blossoming of flowers) was the closest the moon will be to Earth this year.