Astronomy Picture of the Day

Explanation: What's happening at the centre of our Milky Way Galaxy? To help find out, the orbiting Hubble and Spitzer space telescopes have combined their efforts to survey the region in unprecedented detail in infrared light. Infrared light is particularly useful for probing the Milky Way's centre because visible light is more greatly obscured by dust. The above image encompasses over 2,000 images from the Hubble Space Telescope's NICMOS taken last year. The image spans 300 by 115 light years with such high resolution that structures only 20 times the size of our own Solar System are discernable. Clouds of glowing gas and dark dust as well as three large star clusters are visible. Magnetic fields may be channeling plasma along the upper left near the Arches Cluster, while energetic stellar winds are carving pillars near the Quintuplet Cluster on the lower left. The massive Central Cluster of stars surrounding Sagittarius A* is visible on the lower right. Why several central, bright, massive stars appear to be unassociated with these star clusters is not yet understood.