In a surprise, first alien moon discovered is big and gaseous

"It's big and weird by solar system standards," Columbia University astronomy professor David Kipping said of the moon, known as an exomoon because it is outside our solar system.The newly discovered exomoon and the planet it orbits, estimated to be several times the mass of our solar system's largest planet Jupiter, are both gaseous, an unexpected pairing.Kipping and study co-author Alex Teachey, a Columbia graduate student, said their observations using NASA's Hubble Space Telescope and Kepler