Low-resolution samples from PUNCH WFI images 3-D reconstructed over time. a) A PUNCH “photometric” brightness image shows a bright backside CME that erupted from the Sun late October 21, 2025. b) Time series for the volumetric density data are extracted at Earth and compared with Wind in-situ measurements. c) Ecliptic and d) Earth Meridional Cuts through the volume. The CME observed in the PUNCH image is shown at the outer edge of the PUNCH field-of-view nearly two days later in d).
PUNCH Wide Field Images are now able to provide 3-D reconstructions of the inner heliosphere over time(1). The PUNCH 90-degree view around the Sun from Earth captures images of the outward-moving heliospheric structures. For this analysis these images have had the f-corona, stellar residuals, and stray light removed. Computerized tomography analysis converts these images into perspective views of outward moving space weather systems.
The tomography uses “kinematic modeling”: a priori knowledge of how dense structures move through the solar system. The software automatically models how a particular dense feature would appear if seen by PUNCH, compares it to the PUNCH data, and iterates the model to build up a full 3-D version of the inner solar system over time. Figure 1 extends out to 1.8 AU from the Sun, although the 3-D reconstruction is larger still.
Tomographic inversion offers a different way of producing 3-D information than the polarimetry PUNCH uses to locate individual features. A priori understanding of how features propagate (their “kinematics”), coupled with the rapid, wide-field, low-noise images from PUNCH, allows 3-D reconstructions of the inner heliosphere over time. These tomographic models are an approximation of reality, but they represent strong inferences we can draw, from even the unpolarized PUNCH data, about the state of the heliosphere far from Earth. The volumetric cuts in the figure have the inner planets, their orbits, and different interplanetary spacecraft placed correctly for the time of the data, to show how solar wind structures wash over the planets.
This is PUNCH Nugget #31. PUNCH nuggets are archived at the [PUNCH mission website].(https://punch.space.swri.edu/punch_news_archive.php) You can sign up to receive PUNCH nuggets by email.*
