Most nebulae is widespread and that means that they are very large and do not have well-defined boundaries. In visible light, these nebulae can be divided in emission nebulae and reflection nebulae based on how you create the light we see. The emission nebulae contain ionized gas (mostly ionized hydrogen) that produces spectral lines of emission. They are often called H II regions derived from the language of the professional astronomers referring ionized hydrogen.
NASA’s Glenn Research Center Vacuum Chamber 5 provides a testing environment for Glenn’s advanced Solar Electric Propulsion technology needed for future astronaut expeditions into deep space, including to Mars. When you need to test hardware designed
Esta nueva imagen del telescopio espacial Hubble de la NASA/ESA muestra el centro de la nebulosa de la laguna, un objeto con un nombre aparentemente tranquilo, en la constelación de Sagitario. Imagen crédito: NASA, ESA, J. Trauger (Jet Propulson Laboratory)
Images taken in infrared and visible light by NASA's Hubble Space Telescope recount a vivid story of the turbulent birthing process of massive stars. The pictures show that powerful radiation and high-speed material unleashed by "hefty" adult stars residing in the hub of the 30 Doradus Nebula are triggering a new burst of star birth in the surrounding suburbs.