The photo above was taken onboard a high-altitude balloon flight (StratoSpera 3 — the Italian StratoSpera Project) above Tuscany, Italy on September 10, 2011. The altitude is 129,892 ft (39,591 m). This photo is perhaps the highest ever captured from a non-scientific balloon. Photograph Francesco Bonomi.
Because our eyes aren’t as sensitive to the violet wavelengths as they are to blue colors, the sky takes on a bluish hue. At sufficiently high altitudes there are simply too few air molecules to effectively scatter sunlight and the sky is therefore mostly devoid of color. Passengers riding in the Concorde, altitude of 60,000 ft or (18,000 m), were able to observe a mostly black sky during daytime trans-Atlantic crossings.