2015 was an incredible year for making new discoveries in space as our studies of deep space and far away planets continue to evolve.
Remember the "Blood Moon," a rare astronomical phenomenon that took the world by storm when a total lunar eclipse combined with a supermoon? Or when NASA released mind-blowing photos of evidence that liquid water exists on Mars? Or images of the dwarf planet Pluto, boasting majestic mountains and frozen icy plains? How about when NASA astronaut Scott Kelly shared a series of surreal and breathtaking #EarthArt photos from the International Space Station?
Click through the gallery above to relive the most unforgettable moments in space exploration this year.
Related: Best photos from Scott Kelly's #YearInSpace
Related: How astronaut Scott Kelly stays 'mentally strong' spending a year in space