Astronomy Picture of the Day 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 August 5 See Explanation. Clicking on the picture will download the highest resolution version available. *Trapezium: At the Heart of Orion * *Image Credit: * /Data: / Hubble Legacy Archive , /Processing: / Robert Gendler *Explanation: * Near the center of this sharp cosmic portrait , at the heart of the Orion Nebula , are four hot, massive stars known as the Trapezium . Gathered within a region about 1.5 light-years in radius, they dominate the core of the dense Orion Nebula Star Cluster. Ultraviolet ionizing radiation from the Trapezium stars , mostly from the brightest star Theta-1 Orionis C powers the complex star forming region's entire visible glow. About three million years old, the Orion Nebula Cluster was even more compact in its younger years and a recent dynamical study indicates that runaway stellar collisions at an earlier age may have formed a black hole with more than 100 times the mass of the Sun . The presence of a black hole within the cluster could explain the observed high velocities of the Trapezium stars . The Orion Nebula's distance of some 1,500 light-years would make it the closest known black hole to planet Earth. *APOD Event: * APOD Editor to speak at Fermilab on August 8 *Tomorrow's picture: *cosmic streaks ------------------------------------------------------------------------ < | Archive | Submissions | Index | Search | Calendar | RSS | Education | About APOD | Discuss | > ------------------------------------------------------------------------ *Authors & editors: * Robert Nemiroff (MTU ) & Jerry Bonnell (UMCP ) *NASA Official: * Phillip Newman Specific rights apply . NASA Web Privacy Policy and Important Notices *A service of:* ASD at NASA / GSFC *&* Michigan Tech. U.