Picture credits and copyright:

The large icons are made by Freepik from Flaticon is licensed by Creative Commons BY 3.0.

The space images are from NASA and the Jet Propulsion Institute (JPL). See the text under the images and take note of the following:

• Unless otherwise noted, images and video on JPL public web sites (public sites ending with a jpl.nasa.gov address) may be used for any purpose without prior permission, …
• NASA material is not protected by copyright unless noted.

The other images are from the private archive of Hartmut Sieper. All rights reserved.