The Voyager spacecraft (launched in 1977) left our solar system 5 years ago and became the first man-made object to enter interstellar space. A committee led by Carl Sagan (American astronomer, cosmologist, astrophysicist, astrobiologist, etc) agreed upon 116 photos that should be on board. Sagan had this to say about the images:
[...] a collection of 116 pictures (one of which is for calibration) detailing but not limited to human life on earth and the planet itself. Many pictures are annotated with one or many indications of scales of time, size or mass. Some images also contain indications of chemical composition. All measures used on the pictures are first defined in the first few images using physical references.
Here's a gallery of all of the images from Imgur:
Learn more about each image on Wikipedia.