Cosmic sky of pink and blue – Astronomy Now

Splashes of color illustrate the clear distinction between the 2 most populous sort of vivid nebulae in our Milky Means Galaxy. This picture, taken by the wide-field OmegaCAM on the VLT Survey Telescope on the European Southern Observatory in Chile, is dominated by the wine-red hue of an emission nebula known as IC 1284. An emission nebula fairly actually emits gentle from the hydrogen gasoline that types the overwhelming majority of the composition of the nebula. Emission nebulae are star-forming areas, and when ultraviolet gentle from sizzling, younger stars is absorbed by hydrogen, the hydrogen turns into ‘excited’ for a second, and the hydrogen settles again down by emitting gentle at this attribute pink wavelength (generally known as hydrogen-alpha, a typical wavelength of 659 nanometres utilized by skilled and novice astronomers alike). We will see a few of these sizzling, younger stars within the centre of IC 1284.

To the lower-right within the picture, nonetheless, the hue turns decidedly blue with two extra nebulae, catalogued as NGC 6589 and 6590. These are reflection nebulae; they don’t emit the sunshine themselves, however they replicate and scatter the sunshine of close by stars as an alternative. As a result of blue gentle is scattered extra simply than pink, reflection nebulae seem blue. This precept of scattering can also be why the sky seems blue throughout the day, as a result of the environment scatters extra blue gentle than different colors.

Picture: ESO/VPHAS+ Group.