NASA’s PUNCH mission has released its first rainbow-coloured image of the sky, captured by the WFI-2 instrument on 18 April 2025. The image was created by taking photos through all three of the instrument’s polarisers for the first time. This special view shows the polarisation, or angle, of zodiacal light, a faint glow from dust circling the Sun.

The colour in the image represents different angles and strengths of light polarisation. For example, light green shows slight horizontal polarisation, while dark blue shows strong diagonal polarisation. A star symbol marks the Sun’s position. Other stars look white since they’re mostly unpolarised, unlike the 7% polarisation of the zodiacal light. You can see the Pleiades star cluster just above the centre, and the V-shaped Hyades cluster to the upper left.

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Understanding the Sun in 3D

Credit: NASA

The PUNCH mission, short for Polarimeter to Unify the Corona and Heliosphere, aims to uncover how the solar corona spreads through the solar system as the solar wind. It’s the first mission designed to study this in three dimensions using polarised light, which is light that has changed direction after bouncing off particles. This rainbow-style image offers scientists a new way to study how the solar wind moves.

Instruments Behind the Images

PUNCH includes four satellites:

  • 1 x Narrow Field Imager (NFI)
  • 3 x Wide Field Imagers (WFIs)

The NFI acts like a solar shield, blocking the Sun’s bright light to better observe the corona. The WFIs capture faint images of the outer solar corona and the solar wind.

On 27 April 2025, the NFI took a picture of the new moon as it passed by the Sun. In the image, the moon looks full because it’s lit by Earthshine, i.e. sunlight reflected from Earth. This helped NASA confirm that the moon won’t block the NFI’s view of the corona and solar wind.

A dark circle at the bottom marks the shadow of the NFI’s occulter, which hides the Sun. Since it wasn’t yet fully aligned with the Sun, the occulter is surrounded by a ring of light caused by diffraction. A hazy circle from stray light can also be seen, with the moon inside it. Around that is a dimmer part of the sky with less glare.

As the mission continues, scientists will fine-tune the instruments to help reveal new details about the Sun’s corona. Once the data is fully processed, it will combine views from all four spacecraft and remove any unwanted visual effects from space or the cameras.