Noctilucent or “night shining” clouds forming in the mesosphere as seen from the International Space Station

Noctilucent or “night shining” clouds forming in the mesosphere as seen from the International Space Station on May 29, 2016. These clouds form between 47 to 53 miles (76 to 85 kilometers) above Earth’s surface, near the boundary of the mesosphere and thermosphere, a region known as the mesopause. SOFIA will make new observations of atomic oxygen in Earth’s atmosphere, building on the success of previous observations. Credit: ESA/NASA/Tim Peake

SOFIA, the Stratospheric Observatory for Infrared Astronomy, was a Boeing 747SP aircraft modified to carry a 2.7-meter (106-inch) reflecting telescope (with an effective diameter of 2.5 meters or 100 inches). Flying into the stratosphere at 38,000-45,000 feet put SOFIA above 99 percent of Earth’s infrared-blocking atmosphere, allowing astronomers to study the solar system and beyond in ways that are not possible with ground-based telescopes. SOFIA was a joint project of NASA and the German Space Agency at DLR.