By searching for the telltale, periodic dimming of light from distant stars, astronomers can spot orbiting exoplanets tens to hundreds of light-years away. But how do they know what these bodies look like? Perhaps they first try to imagine how the planets in our own Solar System might appear to a faraway alien world.

A pair of scientists has released a detailed catalog of the colors, brightness, and spectral lines of the bodies in our Solar System. They hope to use the catalog as a comparison, so when they spot the blip of an exoplanet, they’ll have a better idea of how it actually looks.

“This is what an alien observer would see if they looked at our Solar System,” study coauthor Lisa Kaltenegger, director of the Carl Sagan Institute at Cornell, told Gizmodo. With this data, astronomers might guess whether an exoplanet is Earth-like, Mars-like, Jupiter-like, or something else entirely.

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All of that incoming data motivated Kaltenegger and coauthor Jack Madden to make this catalog of colors, spectra, and albedos, or how much the planet reflects starlight. They analyzed published data to create fingerprints for 19 objects in our Solar System, including all eight planets, the dwarf planets Pluto and Ceres, and nine moons. Their works is published in the journal Astrobiology.

The full catalog
Graphic: Jack Madden

“It’s smart to leverage everything we know about our own Solar System,” said Kaltenegger. “We have gas giants, the rocky planets, and all these interesting moons. We basically made a reference fingerprint.”

Source: This Solar System Catalog Could Be Key to Finding an Earth-Like Exoplanet

You can find the actual catalog here: http://carlsaganinstitute.org/data/