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APOD:An Annular Solar Eclipse over New Mexico
Credit & Copyright: Colleen Pinski

Explanation: What is this person doing? In 2012, an annular eclipse of the Sun was visible over a narrow path that crossed the northern Pacific Ocean and several western US states. In an annular solar eclipse, the Moon is too far from the Earth to block out the entire Sun, leaving the Sun peeking out over the Moon's disk in a ring of fire. To capture this unusual solar event, an industrious photographer drove from Arizona to New Mexico to find just the right vista. After setting up and just as the eclipsed Sun was setting over a ridge about 0.5 kilometers away, a person unknowingly walked right into the shot. Although grateful for the unexpected human element, the photographer never learned the identity of the silhouetted interloper. It appears likely that the person is holding a circular device that would enable them to get their own view of the eclipse. The shot was taken at sunset on 2012 May 20 at 7:36 pm local time from a park near Albuquerque. Next month, on October 14, a different narrow swath across North and South America will be exposed to a different annular solar eclipse, if the sky is clear. Simultaneously, cloud-free observers almost anywhere on either continent will be able to see a partial solar eclipse.

APOD:NGC 4632: Galaxy with a Hidden Polar Ring
Credit: Jayanne English (U. Manitoba), Nathan Deg (Queen's University) & WALLABY Survey, IDIA/Vislab, CSIRO/ASKAP, NAOJ/Subaru Telescope; Text: Jayanne English (U. Manitoba)

Explanation: Galaxy NGC 4632 hides a secret from optical telescopes. It is surrounded by a ring of cool hydrogen gas orbiting at 90 degrees to its spiral disk. Such polar ring galaxies have previously been discovered using starlight. However, NGC 4632 is among the first in which a radio telescope survey revealed a polar ring. The featured composite image combines this gas ring, observed with the highly sensitive ASKAP telescope, with optical data from the Subaru telescope. Using virtual reality, astronomers separated out the gas in the main disk of the galaxy from the ring, and the subtle color gradient traces its orbital motion. Why do polar rings exist? They could be material pulled from one galaxy as it gravitationally interacts with a companion. Or hydrogen gas flows along the filaments of the cosmic web and accretes into a ring around a galaxy, some of which gravitationally contracts into stars.

APOD:NGC 7331 and Beyond
Image Credit & Copyright: Ian Gorenstein

Explanation: Big, beautiful spiral galaxy NGC 7331 is often touted as an analog to our own Milky Way. About 50 million light-years distant in the northern constellation Pegasus, NGC 7331 was recognized early on as a spiral nebula and is actually one of the brighter galaxies not included in Charles Messier's famous 18th century catalog. Since the galaxy's disk is inclined to our line-of-sight, long telescopic exposures often result in images that evokes a strong sense of depth. The effect is further enhanced in this sharp image by galaxies that lie beyond the gorgeous island universe. The most prominent background galaxies are about one tenth the apparent size of NGC 7331 and so lie roughly ten times farther away. Their close alignment on the sky with NGC 7331 occurs just by chance. Lingering above the plane of the Milky Way, this striking visual grouping of galaxies is known to some as the Deer Lick Group.