In today's image, we see Pandora's Cluster of galaxies. This is a massive closure resulting from the merger of three galaxy clusters. Much of the mass of this, and other clusters, is in the form of dark matter. Dark matter is completely invisible and only detectable through the gravitational interactions. This is often seen in gravitational lensing when the light from more distant galaxies is distorted as it passes through the cluster.

My podcasts are available in video form through this YouTube Channel.

This Podcast is an authorized New Media Mirror Site for APOD. You can access the image and website directly at: Astronomy Picture of the Day. You can use the archive link below the image to select the photo corresponding to the date of this podcast.

I welcome comments and suggestions about these podcasts. I can be reached here: wagnerastronomy@gmail.com

This work is licensed under a Creative Commons Attribution 4.0 International License.