If you need a geeky way to say "I love you" to your special someone this Valentine's Day, look no further than the NASA website.

In addition to Earth earrings, a clever purse holder and your classic NASA logo shirt, it's the only place in the galaxy to get an e-card for your favorite space nerd who loves puns. Plus, you're super cheap, right? Well, it's free.

Just stop by the the NASA Mars site to grab one of 12 Mars-themed Valentine designs. The cards were released last year, just in time for Valentine's Day, showcasing several heart-shaped features discovered by the Mars-based Curiosity rover and other spacecraft. Another card shows off a photo of a surface impression that looks remarkably like the ubiquitous "happy face" and reads, "You make me happy!"

Other heart shapes have also been found on the planet, including by the Mars Reconnaissance Orbiter, revealing that the Red Planet is all heart. Just last year, a heart shape on Pluto was caught on film by another mission. These are not the only shapes spotted in space. Mars is famous for its many optical illusions, including the famous "Face on Mars."

Spotting faces and hearts in space can be explained in the same way we explain seeing bunnies in the clouds. It's a phenomenon called pareidolia, and it accounts for seeing Jesus in your toast and a face on the front of a Dodge Neon. Our brains have evolved to spot familiar shapes as quickly as possible — this helped when we needed to make quick decisions on the hunting ground and the battlefield — and pareidolia is the side effect. It's also been the subject of an insanely bad rap video.

So, send your lover a cheap, fun way to say "I love you even though you're a nerd" — and pass the pareidolia.