These sky or celestial backgrounds are designed for use with the Textgram app for Android. They are 612 pixels squared like other Textgram backgrounds offered on this site.
I found these backgrounds on various sites. I cropped and adjusted intensity of light or dark colours in them to make it easy to get high contrast text on them. I hope the focus will still left on the text rather than on the graphics as these are some amazing images. More colours and themed images will be coming. Enjoy!