AstronomyPicture of the Day—20181205

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2018 December 5

MountEverest Star Trails

ImageCredit & Copyright: Jeff Dai (TWAN)

Explanation:The highest peak on planet Earth is framed in this mountain and night skyscape.On September 30, the digital stack of 240 sequential exposures made with acamera fixed to a tripod at an Everest Base Camp captured the sheer north faceof the Himalayan mountain and foreground illuminated by bright moonlight. Takenover 1.5 hours, the sequence also recorded colorful star trails. Reflecting theplanet's daily rotation on its axis, their motion is along gentle concentricarcs centered on the south celestial pole, a point well below the ruggedhorizon. The color of the trails actually indicates the temperatures of thestars. Blueish hues are from hotter stars, and yellow to reddish hues are fromstars cooler than the Sun.