Which NASA X-ray observatory launched in 1999 studies black holes?

Which NASA X-ray observatory launched in 1999 studies black holes? The answer is the Chandra X-ray Observatory.

NASA launched Chandra aboard the Space Shuttle Columbia on July 23, 1999, during mission STS-93. It was originally called the Advanced X-ray Astrophysics Facility, or AXAF, before being renamed for Indian-American astrophysicist Subrahmanyan Chandrasekhar.

Chandra studies X-rays from some of the universe’s hottest and most energetic environments, including gas falling toward black holes, supernova remnants, neutron stars, and galaxy clusters. Earth’s atmosphere absorbs most cosmic X-rays, so placing the observatory in space is essential. Its grazing-incidence mirrors focus X-rays onto scientific instruments, producing exceptionally sharp images.

A common mix-up is confusing Chandra with Hubble. Hubble mainly observes ultraviolet, visible, and near-infrared light, while Chandra is designed for X-ray astronomy. Chandra is also one of NASA’s Great Observatories, alongside Hubble, the Compton Gamma Ray Observatory, and the Spitzer Space Telescope.