January 17
The Hot Blue Giant
Sun Position
The Sun lies in Capricornus, about 21.0° south of the celestial equator. In the Northern Hemisphere the days are still short but lengthening; in the Southern Hemisphere this is high summer with long, warm evenings.
Sky Highlight
Adhara, one of the sky's strongest sources of ultraviolet light, sits below Sirius in Canis Major. Best placed for Southern Hemisphere observers.
Deep Sky Object
Messier 50, an open cluster about 3,000 light-years away in Monoceros, set against the winter Milky Way. Visible from both hemispheres.
Featured Star
Adhara (ε CMa), a blue-white bright giant in Canis Major, about 430 light-years away. Adhara, once the brightest star in the sky, four million years ago.
Around This Date
- January 17, 1985The European Space Agency's Giotto spacecraft was approved for its mission to intercept Halley's Comet, the probe would pass within 596 kilometers of the nucleus in March 1986, the closest encounter ever made with a comet at that point.
- January 19, 2006NASA's New Horizons launched toward Pluto, carrying some of Clyde Tombaugh's ashes, a fitting cargo for the fastest spacecraft to leave Earth, bound for the world its passenger had discovered.
Some stars pour out a light our eyes were never built to see.