Just as a journey of a thousand miles begins with a single step, and every great book has a first page, every catalog has its first entry, which is what this stunning region — dubbed vdB1 — is. Located about 1,600 light-years away, vdB1 is a reflection nebula with the distinction of being the first object added to the Van den Bergh catalog (vdB), which now contains more than 150 separate entries, all discovered by Canadian astronomer Sidney van den Bergh.
Reflection nebulae are generated when the light from background stars is scattered by interstellar gas and dust clouds. As this region affirms, nebulae of this kind are predominantly blue in color. That's because the scattering of light by interstellar grains of dust tends to be more effective at the shorter end of the electromagnetic spectrum (which is blue/violet). The same effect in our atmosphere is responsible for Earth's sky being tinged blue instead of red (like on Mars).
vdB1 is about 5 light-years across in total. Nearby are two other nebular regions that are also listed in van den Bergh's catalog, V633 Cas (left) and V376 Cas, both of which are associated with the energetic outflows of young variable stars.
Learn more (and see a larger image) here.