That is not our Sun, and the planet is not Mercury or Venus. In fact, the image is not a photo at all, but an artist’s rendition of a star named Gliese 1214 and its super-Earth second planet, GJ 1214b. It’s one of hundreds of exoplanets that astronomers have located by various ingenious means.
These days, the job title of “planet hunter” seems perfectly normal, and we even have an orbiting telescope whose primary mission is hunting for exoplanets, but it wasn’t very long ago that scientists were still searching for proof of just one exoplanet out there. We already knew there were billions and billions of stars, so surely there ought to be other planets too, but we couldn’t find any. The first exoplanet wasn’t found until 1994, and the first exoplanet orbiting a star like ours was discovered a year later.
It hasn’t even been 20 years yet, but our techniques and tools have improved so much that we’ve confirmed over 730 exoplanets already, with another 3,470 candidates awaiting confirmation. The list is so long that we’re categorizing them into groups like Hot Jupiters and Super Earths. (I’m still waiting for the International Astronomical Union to start classifying them like Star Trek: “This is a J-class planet, orbiting a binary star…”)
If you’d like to learn more about how we’re finding so many of what was completely invisible to us just 19 years ago, check out this animated video from PHD Comics. It’s great at explaining, though you may have to rewind a few times.
(Click on the image for details, and then click twice more for a gigantoid version.)