Even if you felt a bit lonely on Valentine's Day here on Earth, there is one heart that belongs to you, way, way out there in the cosmic void. Sure, it's 7.5 billion km away on an icy, airless rock, but don't let the details get you down.
In 2015, the New Horizons spacecraft came across something incredible on Pluto's surface while performing its famous flyby — a massive heart-shaped region that stretches 1600km at its widest. The image above, taken with the spacecraft's Long Range Reconnaissance Imager (LORRI), told the story of a dynamic, geologically active world most scientists had never imagined Pluto to be. Like all good love stories, this image and subsequent, higher-resolution ones have continued to entrance scientists and space fanatics around the world.
"My team worked on this for 15 years and it was an amazing feeling to see the point of light that Pluto was turned into a real place — a planet in front of our eyes," New Horizons principal investigator Alan Stern told Gizmodo. "Seeing the image was emotional for a lot of us, in a good way. It was incredibly pleasing to know that we had succeeded in achieving all of our objectives."
— NASA New Horizons (@NASANewHorizons) February 13, 2017
New Horizons launched in 2006. It remains the fastest spacecraft ever to have blasted off the Earth, which is part of the reason it reached Pluto in record time (a gravity assist from Jupiter also helped). That said, the spacecraft waited nine years to get its first glimpse of Pluto's heart, which was spotted on 13 July 2015, a day before its flyby. Since then, scientists have been debating several different theories about what created the enigmatic crater and how it came to be where it is today.
"It's a little complicated," Stern said. "The left side — the western side — is a vast nitrogen glacier, with about the same surface area as Texas and Oklahoma combined. That appears to be caused by a giant impact that took place on Pluto billions of years ago, which created a basin, and the basin was then filled up as a cold trap, with those volatile nitrogen snows that created the glacier."
While scientists think the impact that initially punched out the heart's left lobe probably took place near Pluto's north pole, today, the heart stretches across the dwarf planet's equator. The migration of volatile elements into Pluto's heart might have made it so heavy that literally caused the planet to tip over billions of years ago. Some researchers have hypothesised that, like Europa or Enceladus, Pluto's heart might be sheltering an enormous subterranean ocean that's contributing to its heaviness.
While New Horizons has long moved on from Pluto and is now venturing into the icy Kuiper Belt, Stern and the New Horizons team will never forget that ephemeral moment of discovery, captured eternally in one stunning image.
"It's the biggest heart in the solar system," Stern said.