The European Space Agency has a trick question for you. It shared a photo showing the glowing orb of the sun with two objects dotting along in front of it, along with this caption: "Is it a bird?" The answer is yes, but the image also shows the International Space Station transiting our star.
The line at a diagonal is the ISS, while the line going up and down shows a bird in flight. The photo comes from an astronomy club at the ESA's European Space Astronomy Centre near Madrid.
Thanks to the camera's perspective, the bird appears to be the same size as the space station. The astronomy club calculated that our feathered friend was flying at about 280 feet (86 meters) away from the camera during its photobomb.
Astrophotographers enjoy the tricky pursuit of trying to photograph the space station as it passes in front of the sun or the moon. It's a challenge to get it just right. This particular transit had a mere 1.2-second window of opportunity. It just so happened a bird passed by at the same moment.
The spectacular photo dates to 2013, but the ESA just released it as part of its Space in Images series on Wednesday.