This illustration, released by NASA on April 27, 2016, shows a star surrounded by a protoplanetary disk. A new study uses data from NASA's Spitzer Space Telescope and four ground-based telescopes to determine the distance from a star to the inner rim of its surrounding protoplanetary disk. Researchers used a method called "photo-reverberation," also known as "light echoes." NASA/UPI

- Image ID: W0MP5P
This illustration, released by NASA on April 27, 2016, shows a star surrounded by a protoplanetary disk. A new study uses data from NASA's Spitzer Space Telescope and four ground-based telescopes to determine the distance from a star to the inner rim of its surrounding protoplanetary disk. Researchers used a method called "photo-reverberation," also known as "light echoes." NASA/UPI
UPI / Alamy Stock Photo
Image ID: W0MP5P