PUNCH News

PUNCH is about to get a close look at a “point-of-no-return” zone surrounding the Sun. Charged particles fly away from the Sun in the form of the steady solar wind and bursty coronal mass ejections (CMEs), and most of those particles escape all the way out past the planets of our solar system. Sometimes, though, particles fall back down, but only if they're below the Sun's Alfvén surface --- named after Nobel-Prize-winning physicist Hannes Alfvén. This surface has been theorized since the 1960s, but has only been explored directly since 2021, when NASA's Parker Solar Probe plunged through it for the first time.

PUNCH tracks space weather and the solar wind itself across the entire inner solar system. This preliminary movie marks the first time a complete halo CME has been tracked all the way across the inner solar system, to impact with Earth.

Although PUNCH is still finishing up commissioning, it is beginning to produce scientifically interesting data. This image is an example: while the complete data processing pipeline is still being refined, the instrument is producing data that reveal the breathtaking beauty of the solar corona and the detailed structure that is the subject of PUNCH science. This image of the corona, during the eruption of a large CME on 6/3/2025, shows the detailed, wispy structure of the background corona and the CME itself.

Downlinking data from space costs money. PUNCH generates a lot of data, which drives the cost of operations – so we do everything we can to reduce the size of each image. We can’t use “lossy” compression algorithms, since a lot of the PUNCH science lives in very faint fluctuations that would be discarded in compression. Coming out of the camera, each WFI image is 8 Megabytes (MB) of 16-bit values. Using JPEG-LS (a lossless algorithm) on the raw images would reduce them to about 3 MB each. But we can (and do) squeeze them further.

PUNCH images of space are now available for download from NASA’s Solar Data Analysis Center (SDAC), in scientific-grade FITS format with relevant pointing and spacecraft-status metadata included. The data are updated twice daily by SDAC from the Science Operation Center (SOC) servers at Southwest Research Institute (SwRI) in Boulder, Colorado – and will continue to update as data arrive from space and are processed by the SOC. The data are also being indexed by the Virtual Solar Observatory. The PUNCH website includes links to documentation for the data and for the mission. Many thanks to Marcus Hughes (PUNCH SOC Lead), Jack Ireland (SDAC Lead), and their teams for opening the taps.

Commissioning of the PUNCH instruments is ongoing. As part of that activity, we ran the first full-orbit NFI (Narrow Field Imager) science sequence on Sunday, April 27. NFI captured several images of the Moon passing by the Sun in the sky, as seen in this unfiltered “Level 0” image in the standard PUNCH pseudocolor palette. The new Moon appears full, because it is illuminated by Earthshine from the full Earth (as seen from the lunar surface). This image is useful to demonstrate that the Moon does not directly interfere with NFI’s primary science, as it is not bright enough to impact the existing pattern of glinting stray light.

There've been lots of stories about this week’s triple-conjunction smiley moon in the media. We happened to catch the conjunction during PUNCH commissioning, along with two other planets besides!