A nebula is a giant cloud of gas (mostly hydrogen and helium) and cosmic dust situated between stars in the interstellar medium. Nebulae serve as sites of stellar birth and death—including emission nebulae that glow from ionized gas, reflection nebulae that scatter starlight, and dark nebulae that obscure background stars.
Source: science.nasa.gov
09/02/2021
It somehow survived an explosion that would surely have destroyed our Sun. Now it is spins 30 times a second and is famous for the its rapid flashes. It is the Crab Pulsar, the rotating neutron star remnant of the supernova that created the Crab Nebula. A careful eye can spot the pulsar flashes in the featured time-lapse video, just above the image center. The video was created by adding together images taken only when the pulsar was flashing, as well as co-added images from other relative times. The Crab Pulsar flashes may have been first noted by an unknown woman attending a public observing night at the University of Chicago in 1957 -- but who was not believed. The progenitor supernova explosion was seen by many in the year 1054 AD. The expanding Crab Nebula remains a picturesque expanding gas cloud that glows across the electromagnetic spectrum. The pulsar is now thought to have survived the supernova explosion because it is composed of extremely-dense quantum-degenerate matter. Who was this mystery woman? Please email leads to the APOD editors.